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The mammalian vestibular epithelia exhibit a remarkably stereotyped organization featuring cellular characteristics under planar cell polarity (PCP) control. PCP mechanisms are responsible for the organization of hair cell morphologic polarization vectors, and are thought to be responsible for the postsynaptic expression of the calcium-binding protein calretinin that defines the utricular striola and cristae central zone. However, recent analyses revealed that subtle differences in the topographic expression of oncomodulin, another calcium-binding protein, reflects heterogeneous factors driving the subtle variations in expression. Calbindin represents a third calcium-binding protein that has been previously described to be expressed in both hair cells and afferent calyces in proximity to the utricular striola and crista central zone. The objective of the present investigation was to determine calbindin’s topographic pattern of expression to further elucidate the extent to which PCP mechanisms might exert control over the organization of vestibular neuroepithelia. The findings revealed that calbindin exhibited an expression pattern strikingly similar to oncomodulin. However, within calyces of the central zone calbindin was colocalized with calretinin. These results indicate that organizational features of vestibular epithelia are governed by a suite of factors that include PCP mechanisms as well others yet to be defined.

The LIM homeodomain transcription factor Lmx1a shows a dynamic expression in the developing mouse ear that stabilizes in the non-sensory epithelium. Previous work showed that Lmx1a functional null mutants have an additional sensory hair cell patch in the posterior wall of a cochlear duct and have a mix of vestibular and cochlear hair cells in the basal cochlear sensory epithelium. In E13.5 mutants, Sox2-expressing posterior canal crista is continuous with an ectopic “crista sensory epithelium” located in the outer spiral sulcus of the basal cochlear duct. The medial margin of cochlear crista is in contact with the adjacent Sox2-expressing basal cochlear sensory epithelium. By E17.5, this contact has been interrupted by the formation of an intervening non-sensory epithelium, and Atoh1 is expressed in the hair cells of both the cochlear crista and the basal cochlear sensory epithelium. Where cochlear crista was formerly associated with the basal cochlear sensory epithelium, the basal cochlear sensory epithelium lacks an outer hair cell band, and gaps are present in its associated Bmp4 expression. Further apically, where cochlear crista was never present, the cochlear sensory epithelium forms a poorly ordered but complete organ of Corti. We propose that the core prosensory posterior crista is enlarged in the mutant when the absence of Lmx1a expression allows JAG1-NOTCH signaling to propagate into the adjacent epithelium and down the posterior wall of the cochlear duct. We suggest that the cochlear crista propagates in the mutant outer spiral sulcus because it expresses Lmo4 in the absence of Lmx1a.

Many developmental disorders of the inner ear are manifested clinically as delayed motor development and challenges in maintaining posture and balance, indicating involvement of central vestibular circuits. How the vestibular circuitry is rewired in pediatric cases is poorly understood due to lack of a suitable animal model. Based on this, our lab designed and validated a chick embryo model to study vestibular development in congenital vestibular disorders. The developing inner ear or “otocyst” on the right side of 2-day-old chick embryos (E2) was surgically rotated 180° in the anterior–posterior axis, forming the “anterior–posterior axis rotated otocyst chick” or ARO chick. The ARO chick has a reproducible pathology of a sac with truncated or missing semicircular canals. A sac is the most common inner ear defect found in children with congenital vestibular disorders. In E13 ARO chicks, the sac contained all three cristae and maculae utriculi and sacculi, but the superior crista and macula utriculi were shortened in anterior–posterior extent. Also, the number of principal cells of the tangential vestibular nucleus, a major avian vestibular nucleus, was decreased 66 % on the rotated side. After hatching, no difference was detected between ARO and normal chicks in their righting reflex times. However, unlike normal chicks, ARO hatchlings had a constant, right head tilt, and after performing the righting reflex, ARO chicks stumbled and walked with a widened base. Identifying the structure and function of abnormally developed brain regions in ARO chicks may assist in improving treatments for patients with congenital vestibular disorder.

We report on a new xyloside conjugated to BODIPY, BX and its utility to prime fluorescent glycosaminoglycans (BX-GAGs) within the inner ear in vivo. When BX is administered directly into the endolymphatic space of the oyster toadfish (Opsanus tau) inner ear, fluorescent BX-GAGs are primed and become visible in the sensory epithelia of the semicircular canals, utricle, and saccule. Confocal and 2-photon microscopy of vestibular organs fixed 4 h following BX treatment, reveal BX-GAGs constituting glycocalyces that envelop hair cell kinocilium, nerve fibers, and capillaries. In the presence of GAG-specific enzymes, the BX-GAG signals are diminished, suggesting that chondroitin sulfates are the primary GAGs primed by BX. Results are consistent with similar click-xylosides in CHO cell lines, where the xyloside enters the Golgi and preferentially initiates chondroitin sulfate B production. Introduction of BX produces a temporary block of hair cell mechanoelectrical transduction (MET) currents in the crista, reduction in background discharge rate of afferent neurons, and a reduction in sensitivity to physiological stimulation. A six-degree-of-freedom pharmacokinetic mathematical model has been applied to interpret the time course and spatial distribution of BX and BX-GAGs. Results demonstrate a new optical approach to study GAG biology in the inner ear, for tracking synthesis and localization in real time.

Gyraulus crista is often a dominant component of lentic freshwater snail communities because it may occur in densities of hundreds of individuals/m2 across continents and in lentic water types. A study on the occurrence and conchological variability of the shell of G. crista was carried out on five different types of substrates in the anthropogenic woodland ponds at thirteen study sites. In order to answer the question of whether the existence of this species in different forms is affected by the quality of the inhabited substrates, various physico-chemical properties of the water, different bottom sediments and water level fluctuations, we examined the variation of forms across 5990 specimens of G. crista in woodland ponds. This research, which was supported by Redundancy Analysis (RDA), showed a highly significant association of G. c. spinulosus with leaf deposits and G. c. cristatus for T. latifolia remains. G. crista nautileus was mainly associated with T. latifolia and also with G. aquatica remains. They also showed no statistically significant relationship between the occurrence of particular conchological G. crista forms and different physico-chemical properties of water.

17β-estradiol (E2) is considered to modulate the ATP synthase activity through direct binding to the oligomycin sensitive-conferring protein. We have previously demonstrated that E2 increases the amplitude of depolarization associated with the addition of ADP to energized mitochondria (i.e., to initiate a phosphorylative cycle) suggesting a direct action on the phosphorylative system of mitochondria. The purpose of the present study was to investigate the underlying mechanisms responsible for this effect. We show here that E2 modulates the activity of mitochondrial ATP synthase by promoting the intrinsic uncoupling ("slipping") of the ATP synthase. E2 depressed RCR, ADP/O ratio and state 3 respiration, whereas state 4 respiration was increased and VFCCP (uncoupled respiration) remained unaltered. In contrast to the stimulatory effect on state 4 respiration, state 2 respiration and Volig were not affected by E2. The effect of E2 appeared to be directed towards ATP synthase, since glutamate/malate respiration, uncoupled from the electron transport chain, was unaffected by E2. Apparently, E2 allows a proton back-leak through the Fo component of ATP synthase. This action of E2 is dependent on the presence of ATP, is more pronounced at high membrane potentials, and it is reversed by oligomycin (a Fo-ATP synthase inhibitor) but not by resveratrol (a F1-ATP synthase inhibitor). Altogether, our data provide a mechanistic explanation for the effect of E2 at the level of mitochondrial ATP synthase.

The mode of synaptic transmission in the vestibular periphery, between type I hair cells and their associated calyx terminal, has been the subject of much debate. The close and extensive apposition of pre- and post-synaptic elements has led some to suggest potassium (K(+)) accumulates in the intercellular space and even plays a role in synaptic transmission. During patch clamp recordings from isolated and embedded hair cells in a semi-intact preparation of the mouse cristae, we noted marked differences in whole-cell currents. Embedded type I hair cells show a prominent droop during steady-state activation as well as a dramatic collapse in tail currents. Responses to a depolarizing voltage step (-124 to +16 mV) in embedded, but not isolated, hair cells resulted in a40 mV shift of the K(+) equilibrium potential and a rise in effective K(+) concentration (50 mM) in the intercellular space. Together these data suggest K(+) accumulation in the intercellular space accounts for the different responses in isolated and embedded type I hair cells. To test this notion, we exposed the preparation to hyperosmotic solutions to enlarge the intercellular space. As predicted, the K(+) accumulation effects were reduced; however, a fit of our data with a classic diffusion model suggested K(+) permeability, rather than the intercellular space, had been altered by the hyperosmotic change. These results support the notion that under depolarizing conditions substantial K(+) accumulation occurs in the space between type I hair cells and calyx. The extent of K(+) accumulation during normal synaptic transmission, however, remains to be determined.

Effects of clinorotation on the mitochondrial ultrastructure in cells of meristem, distal and central elongation zones of 3- and 5-day-old etiolated roots of pea seedling roots were studied. It was shown that mitochondria in cells of examined root growth zones revealed a different sensitivity to clinorotation. The ultrastructure of mitochondria in the meristem and central elongation zone cells did not substantially change in comparison with stationary control. At the same time, changes in the mitochondrial ultrastructure in cells of the distal elongation zone under clinorotation were observed, namely: decrease in the size of mitochondria, as well as increase in both matrix electron density and crista volume. Such changes in the mitochondrial ultrastructure under clinorotation are supposed to display the rearrangements of energy metabolism in cells of the distal elongation zone in these conditions.

At embryonic day 8.5, the LIM-homeodomain factor Lmx1a is expressed throughout the otic placode but becomes developmentally restricted to non-sensory epithelia of the ear (endolymphatic duct, ductus reuniens, cochlea lateral wall). We confirm here that the ears of newborn dreher (Lmx1a (dr)) mutants are dysmorphic. Hair cell markers such as Atoh1 and Myo7 reveal, for the first time, that newborn Lmx1a mutants have only three sensory epithelia: two enlarged canal cristae and one fused epithelium comprising an amalgamation of the cochlea, saccule, and utricle (a "cochlear-gravistatic" endorgan). The enlarged anterior canal crista develops by fusion of horizontal and anterior crista, whereas the posterior crista fuses with an enlarged papilla neglecta that may extend into the cochlear lateral wall. In the fused endorgan, the cochlear region is distinguished from the vestibular region by markers such as Gata3, the presence of a tectorial membrane, and cochlea-specific innervation. The cochlea-like apex displays minor disorganization of the hair and supporting cells. This contrasts with the basal half of the cochlear region, which shows a vestibular epithelium-like organization of hair cells and supporting cells. The dismorphic features of the cochlea are also reflected in altered gene expression patterns. Fgf8 expression expands from inner hair cells in the apex to most hair cells in the base. Two supporting cell marker proteins, Sox2 and Prox1, also differ in their cellular distribution between the base and the apex. Sox2 expression expands in mutant canal cristae prior to their enlargement and fusion and displays a more diffuse and widespread expression in the base of the cochlear region, whereas Prox1 is not detected in the base. These changes in Sox2 and Prox1 expression suggest that Lmx1a expression restricts and sharpens Sox2 expression, thereby defining non-sensory and sensory epithelium. The adult Lmx1a mutant organ of Corti shows a loss of cochlear hair cells, suggesting that the long-term maintenance of hair cells is also disrupted in these mutants.

The present study was conducted to visualize the ultrastructural features of vestibular efferent boutons in the oyster toadfish, Opsanus tau. The crista ampullaris of the horizontal semicircular canal was processed for and examined by routine transmission electron microscopy. The results demonstrate that such boutons vary in size and shape, and contain a heterogeneous population of lucent vesicles with scattered dense core vesicles. Efferent contacts with hair cells are characterized by local vesicle accumulations in the presynaptic terminal and a subsynaptic cistern in the postsynaptic region of the hair cell. Serial efferent to hair cell to afferent synaptic arrangements are common, particularly in the central portion of the crista. However, direct contacts between efferent terminals and afferent neurites were not observed in our specimens. The existence of serial synaptic contacts, often with a row of vesicles in the efferent boutons lining the efferent-afferent membrane apposition, suggests that the efferent influence on the crista may involve both synaptic and nonsynaptic, secretory mechanisms. Further, it is suggested that differences in more subtle aspects of synaptic architecture and/or transmitter and receptor localization and interaction may render the efferent innervation of the peripheral crista less effective in influencing sensory processing.

Vascular change may contribute to age-related vestibular dysfunction. Previously, we reported a significant age-related decrease in blood flow (BF) and mean capillary diameter (D(cap)) in the rat posterior canal crista. The purpose of this study was to examine an otolith organ, the utricle, for similar changes. Old male Fischer 344 rats (O; 28-31 mos) were anesthetized, and the left cardiac ventricle was transcutaneously injected with radioactive microspheres to determine BF. The temporal bones were removed, fixed, and decalcified. The utricles were dissected free and placed into a gamma counter with the reference samples. The specimens were then plastic embedded and serially sectioned at 1 microm according to the vertical section technique. Microsphere surface counts were made and neuroepithelial BF calculated. A systematic random set of sections was sampled and analyzed using stereological techniques for estimates of D(cap), capillary surface area/unit volume (S(v,cap)), capillary length/ unit volume (L(v,cap)), and volume of utricular neuroepithelium (V(ut)). Using these data, total capillary surface (S(cap)) and total length (L(cap)) were calculated. Statistical comparisons were made with data from our previous study of young animals (Y; 3-6 mos). Results indicate a significant age-related decrease in BF (Y = 0.125 microL/min, O = 0.062 microL/min; P = 0.003), D(cap) (Y = 5.95 micro, O = 4.57 microm; P = 0.0002), S(vcap) (Y = 12.33 mm2/mm3, = 9.87 mm2/mm3, P = 0.016), S(cap) (Y = 0.178 mm2, O = 0.129 mm2; p = 0.01), and V(ut) (Y = 0.014 mm3, O = 0.013 mm3; P = 0.04) with no significant change in L(v,cap) (Y = 655 mm/mm3, O = 686 mm/mm3, P = 0.41) or L(cap) (Y = 9.47 mm, O = 8.96 mm; P = 0.49). These age-related vascular changes are likely to have a significant impact on utricular physiological and thus, dysequilibrium.

The peripheral and central tonotopy of auditory receptors of the bushcricket Pholidoptera griseoaptera is described. Out of 24 auditory receptor cells of the crista acustica 18 were identified by single-cell recordings in the prothoracic ganglion and complete staining with neurobiotin. Proximal receptor cells of the crista acustica were most sensitive to 6 kHz, with medial cells being sensitive to 20–30 kHz, whereas distal cells were most sensitive to frequencies higher than 50 kHz. Projection areas within the auditory neuropile in the prothoracic ganglion were to- notopically arranged. Proximal cells projected anteriorly, medial cells ventrally and posteriorly, and distal cells to more dorsal regions. Identified receptor cells revealed an interindividual variability of tuning and central projections. Receptor cells from the intermediate organ of a bushcricket were identified for the first time. Receptors of the distal intermediate organ were broadly tuned and less sensitive than those of the crista acustica. Receptor cells of the proximal intermediate organ were most sensitive to frequencies below 10 kHz. They projected in anterior portions of the auditory neuropile, whereas cells of the distal intermediate organ had terminations spread over almost the whole auditory neuropile.

Electron microscope tomography was used to examine the membrane topology of brown adipose tissue (BAT) mitochondria prepared by cryofixation or chemical fixation techniques. These mitochondria contain an uncoupling protein which results in the conversion of energy from electron transport into heat. The three-dimensional reconstructions of BAT mitochondria provided a view of the inner mitochondrial membrane different in important features from descriptions found in the literature. The work reported here provides new insight into BAT mitochondria architecture by identifying crista junctions, including multiple junctions connecting a crista to the same side of the inner boundary membrane, in a class of mitochondria that have no tubular cristae, but only lamellar cristae. Crista junctions were defined previously as the tubular membranes of relatively uniform diameter that connect a crista membrane with the inner boundary membrane. We have also found that the cristae architecture of cryofixed mitochondria, including crista junctions, is similar to that found in chemically fixed mitochondria, suggesting that this architecture is not a fixation artifact. The stacks of lamellar cristae extended through more of the BAT mitochondrial volume than did the cristae we observed in neuronal mitochondria. Hence, the inner membrane surface area was larger in the former. In chemically fixed mitochondria, contact sites were easily visualized because the outer and inner boundary membranes were separated by an 8 nm space. However, in cryofixed mitochondria almost all the outer membrane was observed to be in close contact with the inner boundary membrane.

In 1996 Montgomery proposed an ontogenetic shift in the use of visual and non-visual senses in Antarctic notothenioid fishes, with visual dominance in larval fishes giving way to non-visual senses in adults. One prediction of the hypothesis is timing differences in the development of the respective sensory systems, with the visual system expected to develop earlier than the other systems. The volume of certain brain centres can be determined from fixed material and should correlate with sensory development. This study determined the relative volumes of visual and lateral line brain areas, and relative eye size as a function of fish length in Pleuragramma antarcticum.The relative volume of optic tectum was largest in larval fish, exhibiting a negative allometry with growth. The eminentia granularis, and crista cerebellaris (lateral line associated areas) were not recognisable in the smallest larvae; they became differentiated at standard lengths of 10–20 mm and their relative volumes continued to increase over the size range of fish studied (up to 150 mm standard length). Relative eye diameter decreased dramatically over the size range 5–25 mm and then increased such that relative eye diameter doubled over the size range 25–30 mm. A similar, but less extreme, pattern was seen over the size range 30–60 mm. Above 60 mm relative eye diameter increased slightly with size. Our interpretation is that eye growth and somatic growth are on separate trajectories, and the breaks in the relative eye diameter curve result from overwinter periods when somatic growth is static, but the eye continues to grow. These results provide support for the ontogenetic shift hypothesis, and indicate that the timing of the shift probably occurs after the second winter.

Data from four A3 radio wave circuits in central Europe are used to analyse the representativeness of the ionization and gravity wave activity pattern in the lower ionosphere (∼85 – 100 km) in the CRISTA experiment interval (3 – 12 November 1994) for the given conditions. It has been found that the CRISTA experiment interval was run under conditions, which are highly representative both of October – November 1994 and autumn, low-moderate solar activity, the descending phase of solar cycle conditions, i.e. CRISTA measurements may be considered to provide values identical with, or close to climatological values (at least for central Europe, h = 85 – 100 km).

The postembryonic development of the morphology and anatomy of the complex tibial organ in the foreleg of the bushcricket Ephippiger ephippiger is described. All the receptor cells are present in the subgenual organ, the intermediate organ and the crista acustica in the 1st larval instar. Generally, even in the 1st instar, the arrangement of the scolopidia in the three organs resembles the adult structure. The acoustic trachea, the tympana, the tympanal covers and the acoustic spiracle develop step by step in subsequent instars. The acoustic trachea resembles the adult structure for the first time in the 4th instar, although its volume is still small. The auditory threshold curves recorded from the tympanal nerve in instars 4, 5 and 6 show the same frequency maxima as those in the adult. The overall sensitivity significantly increases after the final moult. The dimensions of structures that lie within the crista acustica and that are probably involved in stimulus transduction and in frequency tuning have been analysed. The dorsal wall of the anterior trachea, the tectorial membrane and the cap cells have similar dimensions, especially in the last three instars and in adults.

1. Insects of the family Haglidae are relicts of primitive Ensifera. Members of this group display acoustic behaviour in the typical ensiferan pattern, with males producing stereotyped acoustic signals by tegminal stridulation. They are closely related to the major groups of acoustic Ensifera, but their auditory system has not been previously studied. I present here a description of the morphology, and physiology of the peripheral auditory system of Cyphoderris monstrosa. 2. The tympana of C. monstrosa are similar to those of Tettigoniidae, but less well-differentiated from normal leg cuticle. The acoustic trachea is well-developed, but does not form a single, continuous tube in the leg proximal to the tympana. The organization of the auditory organ is similar to the Tettigoniidae, with the tibial organ comprising the subgenual organ, intermediate organ, and crista acustica. Projections of the tibial organ sensory cells to the prothoracic ganglion are also typical of acoustic Orthoptera. The meso- and metathoracic legs possess tibial organs similar to that of the prothoracic leg, although lacking tympana and well-developed acoustic tracheae. Central projections of the mesothoracic tibial organ are similar to those of the prothoracic. 3. Auditory whole nerve responses are not tuned to the frequency of the species calling song. Auditory best frequency (BF) is 2 kHz; calling song frequency is 12 kHz. Threshold intensity levels at BF are typical for insect hearing organs (35–45 dB SPL). The response of the auditory organ is not strongly directional at the calling song frequency. Occlusion of the acoustic trachea has no effect on the sensitivity, tuning, or directionality of the auditory system. Occlusion of either of the tympana alone also has no effect on auditory responses, but occlusion of both tympana leads to a marked decrease in sensitivity. Tuning is not affected. The tibial organ of the mesothoracic leg is sensitive to airborne sound at low frequencies (BF = 1 kHz) with thresholds comparable to the ear. 4. The auditory system of C. monstrosa is a pressure receiver, adapted to low frequency sensitivity. This low frequency tuning, in contrast to the calling song frequency, suggests an auditory system adapted to another function in addition to intraspecific communication.

Electron microscopic study of femoral arteries of white rats exposed to prolonged general vibration at a frequency of 100 Hz with an amplitude of 0.5-0.7 mm has been performed. Light and dark smooth muscle cells, as well as unchanged cells have been found in the vascular media of experimental animals. Light cells are swollen with destroyed myofilaments and great number of microtubules in cytoplasm. Dark cells are characterized by coagulation necrosis and melting of myofilaments. Vibration was shown to cause marked structural changes in smooth muscle cells mitochondria: destruction of internal and external membranes, increasing matrix osmophilia or swelling of mitochondria accompanied by crista fragmentation, as well as matrix clarification and disappearance. Morphometric analysis indicates a considerably decreased energy production by smooth muscle cell mitochondria. It has been concluded that vibrations have a damaging effect on medial smooth muscle cells of the femoral artery in the experimental animals.

The transparent labyrinth of young eels (Anguilla anguilla L.) was used in toto for studying the configuration of cupula displacement, deflection of the hair bundle, and correlated changes in transepithelial voltage (delta TEV) and nerve activity (delta NA) in the semicircular canal. Microcapillaries were introduced into the canal through holes produced by a microthermocauter. Mechanical stimulation was applied either by injection of fluid into the ampulla or by electromagnetically displacing ferrofluid as a piston within the canal. Motion of individual kinocilia, stained cupulae or the ferrofluid piston was analysed by double-exposed microphotographs, photodiodes, or a video-system. The three-dimensional cupula displacement configuration was found to be piston- to diaphragm-like. Hair bundles at different sites on the crista exhibit differences in amplitude and time course of deflection. The transfer factor between shifts of the canal fluid and the tips of the kinocilia is 0.4-0.6. Displacements in opposite directions induce delta TEV and delta NA of opposite sign. Various tests confirmed delta TEV to reflect receptor potential responses. Nerve activity adapts to a tonic response with a time constant of 6.4 s. No similar adaptation occurred in delta TEV. Stimulus-response curves of TEV- and NA-responses are similar and sigmoid in shape with saturation at ciliary deflections of roughly +6 degrees and -3 degrees.

1. The responses of single acoustic neurons to sound stimuli were recorded by capillary microelectrodes at three sequential stations (the receptors, the ventral cord, and the supraesophageal ganglion) of the auditory pathway of the tettigoniid speciesDecticus verrucivorus. 2. To characterize the responses to sound stimuli varying in intensity, frequency, direction, and duration, the following four basic measures were used: response fields (threshold and constant-response curves vs. frequency), intensity characteristics, directional diagrams, and the time course of the neuronal discharge. These measures are employed to compare both neurons at each station and those at different levels, so that the progressive development of neuronal information processing can be followed from the receptors to the brain. 3. At the receptor level two groups of neurons can be distinguished; on the basis of general morphological comparisons their origins are ascribed to the crista acustica (group a) and the intermediate organ (group b) (Fig. 2). 4. Receptor cells of group a differ among themselves in characteristic frequency and threshold. Bach carries out a precise coding of intensity and direction in its nearthreshold region (Figs. 1, 3, 5 and 6), but with stimuli more than about 30 dB above threshold, the response saturates. The response areas of different cells overlap so that, taken as a whole, they ensure relatively precise transduction of the above-mentioned stimulus parameters over a wide range of frequencies and intensities. 5. Group-b receptor cells (intermediate organ) are considerably less sensitive to changes in stimulus frequency, intensity, and direction (Figs. 2 and 10). Like those of group a they respond nearly tonically to stimuli sufficiently above threshold (Figs. 7 and 11), though with long stimuli a slight initial phasic component is discernible (Fig. 8). 6. The neurons of the ventral cord receive synaptic input from several tympanic units of the same side, and in many cases informations of the opposite side as well. The observed unilateral and bilateral effects can be brought about by facilitation and inhibition. As a result of this complex integration the discrimination of certain sound parameters available in the receptor-cell responses can, at the ventral-cord level, either be enhanced considerably or be degraded. 7. Whereas frequency selectivity at the higher levels is severely degraded in comparison with that available at the receptor level (Figs. 13, 14, 15 and 29), the precision of intensity and direction coding is distinctly enhanced (Figs. 17, 18, 30 and 31). The response patterns recorded inchide those of phasic units, tonic units, and intermediate forms, as well as units which alter the pattern with stimulus conditions. Several of these are well matched to specific features of the stridulation sounds of the species (Figs. 20 and 21). 8. As far as the processing of frequency and intensity is concerned, only quantitative differences—no fundamental or qualitative differences—were observed in comparisons of the ventral cord and the supraesophageal ganglion (Figs. 24 and 26). With respect to the coding of direction and form of the response pattern, however, characteristic novel units are found in the supraesophageal ganglion (Figs. 25, 27, 28 and 33). Finally, the extent to which “recognition filters” exist at the level of the ventral cord and the supraesophageal ganglion is discussed in terms of the known aspects of acoustic behavior.

This study of the ultrastructure of the auditory sensilla of the New Zealand weta, Hemideina crassidens, is the first such study on a member of the orthopteran Superfamily Gryllacridoidea. Ultrastructure of the auditory sensilla is similar in all of the tibial mechanosensory organs, here called subgenual organ, intermediate organ and crista acoustica by analogy with comparable structures in Tettigoniidae. Distal to each sensory soma is a dendrite containing multiple ciliary rootlets that fuse into a single ciliary root. This splits into nine root processes that pass around the outside of the proximal basal body and then rejoin at the level of the distal basal body, distal to which the dendrite has a modified ciliary structure with a circlet of nine peripheral paired tubes and rods as it passes through the proximal extracellular space. It is then enclosed by a zone of scolopale cell cytoplasm before expanding into a dilatation within the distal extracellular space. In some sensilla this space is partially occluded by electron dense material which is part of the scolopale cell. Distal to the dilatation the cilium shrinks and ends surrounded by the scolopale cap. Accessory cells consist of glia enwrapping the sensory neuron in the region of its soma, the scolopale cell surrouinding the ciliary portion of the dendrite, and the attachment cell surrounding the scolopale cell and scolopale cap and connected to them by desmosomes. The attachment cells are filled with microtubules in differing densities and orientations. Lamellae are present in the acellular matrix surrounding the attachment cells. Banded fibres, presumably of collagen, are also present in the matrix.

The papilla neglecta in the cat vestibule was studied under a scanning electron microscope. This papilla appears as a small mound of cells on the utricle near the posterior semicircular canal crista. The number of sensory hair bundles on the papilla ranged from 11–64 in 7 ears examined (average, 37). Although this crista-like endorgan was regularly found in the cat, its function may not be important in that the number of sensory hair cells is only 1/150 of those counted on guinea pig posterior semicircular canal crista.

Three theories are discussed dealing with the origin of the Menière attack: 1) The hypothesis of pressure induced changes is disproved. 2. The stimulation of the crista epithelium by a mechanical cupula deviation has been investigated. The results showed that the changes in action potential frequency of the ampullary nerve induced by maintained bending of the cupula, always declined and returned to resting potential frequency within a very short period of time usually within 1 min. Preventing the "elastic return" of the cupula did not change the time constant of this response decline. This proves that a Menière nystagmus lasting for hours, can not be elicited by a mechanical deformation of the cupula. 3) The paralyzing influence on vestibular nerve fibres by K+ ions in endolymph, leaking into perilymph spaces has earlier been demonstrated by the author. When the distended membranous labyrinth ruptures at predestined weak spots, leaking endolymph may reach and paralyze different nerve branches. This can explain all the main symptoms of a Menière attack.

1. The lateral line lobe consists of two structures, a layer of cerebellar material, the crista cerebelli overlying the medullary gray. Field potentials and single cell recordings made after stimulating the lateral line nerve and the caudal lobe of the cerebellum show that the primitive Purkinje cells (pP cells) of the crista can be excited by stimulating the large parallel fibre input running from the caudal lobe and (some cells) by stimulating the lateral line nerve. The parallel fibres do not appear to be involved in these latter responses and their role is unknown. 2. Apart from the extrinsic origin of the parallel fibres the crista cerebelli also differs from the cerebellum by having no identifiable climbing fibres. Stellate cell inhibition however appears to be present. 3. The small secondary lateral line cells in the gray layer receive punctate primary afferent inputs from one lateral line organ and a diffuse polysynaptic inhibitory input which can be seen as ipsps evoked in anterior lateral line gray cells by posterior lateral line nerve stimulation. 4. The lateral line inputs to the pP cells are highly variable and, in contrast to the gray cells pP cells show diffuse receptive fields when tested with “natural” stimuli. 5. Stimulation of the pP cells inhibits the gray cells and it seems that they are responsible for the inhibitory effect noted in (3). 6. It is suggested that pP cells with diffuse receptive fields inhibiting gray cells with punctate receptive fields could form a sensory lateral inhibition mechanism in the lateral line lobe. 7. When the responses of primary fibres in the lateral line nerve and secondary lateral line gray cells to measured physiological stimuli (water displacements at 30 Hz) are compared such a lateral inhibition seems to be present in the lateral line lobe. Secondary gray cells have response attenuation curves of 6–17 dB/cm as the stimulating probe is moved away from the units receptive field. The primary fibres show symmetrical curves with slopes of 4–6 dB/cm which corresponds to the calculated stimulus attenuation.

The renal appendages of the octopods Octopus vulgaris Lam., Eledone moschata Lam. and of the decapods of the order Sepioidea Sepia officinalis L., and of sea water suggest osmotic filtration combined with active ion transport and methods of light and electron microscopy and of cytochemistry. The cells of the excretory epithelium are polarised; in all species, they show a basal labyrinth with a thick positive PAS and alcian blue reaction. The cells contain numerous mitochondria, which show the crista type of internal structure, and in the basal as well as in the apical part there are lysosomal dense bodies with high phosphatase activity. The fine structure, the osmolality and the ionic composition of the blood, the urine and of sea water suggest osmotic filtration combined with active ion transport and apocrine excretory secretion and reabsorption. In Sepia only, crypts of the epithelium were found to contain spherical mixed crystals which contain Ca, K, Na, Mg, Cl, S, P according to the electron probe and cytochemical analysis; the matrix shows concentric layers, it gives a positive PAS and alcian blue reaction. The chemical composition, the genesis and the possible function of these crystals are discussed.

1. The peripheral tympanal region of the Tettigonioidea (long-horned grasshoppers) has been investigated by means of the scanning electron microscope. 2. The tympana are composed of two membranous parts having different structure. There is an outer, ellipsoid region with a honeycomb structure comparable to that of the surface of the forelimb exoskeleton; around this lies a thin crescent-shaped membrane with a fibrillar texture. The latter part is probably relatively elastic and capable of oscillation. 3. The actual site of the auditory receptors in these grasshoppers, the crista acoustica, takes the form of a row of scolopidia; the sizes of the scolopidia decrease progressively from proximal to distal. The cap cells of the scolopidia are covered by the tectorial membrane; in the middle and distal region of this membrane there are supporting bands running lateral to the cap cells.

In the butterflyfishChaetodon trifasciatus, the labyrinth is characterized by its elevated form and especially the size of the vertical canals, the almost circular form of the horizontal canal and its posterior opening not directly in the utriculus but in the common pillar of the two vertical canals. There is an almost complete separation between utriculus and sacculus which are only linked by a virtual pore. The lagena, which is medially situated to the posterior part of the sacculus, is separated from it by an incomplete vertical wall. There are two maculae neglectae, the anterior macula being situated in the pore separating utriculus from sacculus and filling this pore, the posterior in a gutter of the floor of the utriculus. A long and narrow endolymphatic canal, originating from the sacculus close to the communication with the utriculus, follows the common pillar of the two vertical canals and widens into an endolymphatic sac at the top of the membranous labyrinth. The innervation of the labyrinth is made by the acoustic ganglion, which is connected to the brain by two roots and elongated into three parts: the anterior part innervates the anterior and horizontal cristae and the utricular and saccular maculae; the middle part innervates the macula sacculae and the macula neglecta 1; the posterior part innervates the macula neglecta II, the macula lagenae and the posterior crista. The important size of the vertical canals and the almost circular form of the horizontal canal may reflect very precise locomotory aptitudes.

With electrophysiological methods, it has been possible to demonstrate in the frog the existence of fibers projecting onto the crista ampullaris of the vertical anterior semicircular canal from several other ipsilateral vestibular receptors, especially the crista of the horizontal semicircular canal, possibly the crista of the vertical posterior canal and otolithic receptors. The fibers which connect vestibular receptors within the peripheral vestibular apparatus have been called “receptor-receptor fibers”. The percentage of receptor-receptor fibers in the ampullary nerve of the vertical anterior canal is about 6–8%.

1. Removing the anterior tympanic membrane of the tettigoniidCaedicia simplex did not significantly alter either the tuning or the intensity-response characteristics of individual auditory fibers recorded in the leg nerve (Figs. 2 and 3). However, this operation did make the auditory sensilla in the crista acustica accessible for physiological recording. 2. The physiological responses of individual auditory receptors in the crista acustica have been recorded and the frequency-threshold characteristics of identified sensilla have been measured for sound frequencies between 1 kHz and 40 kHz. 3. In response to an acoustic stimulus a slow hyperpolarising potential (1–2 mV), lasting the duration of the tone and superimposed hyperpolarising spike potentials (2–4 mV) were recorded in the attachment cell of the sensillum (Fig. 4A). In two of the 28 sensilla from which recordings were obtained, depolarising spike potentials were recorded superimposed on the hyperpolarising potential (Fig. 4B). On rare occasions, depolarising spike potentials were recorded in the absence of any slow potential. Lucifer Yellow was successfully injected into the attachment cell of a sensillum only when the slow potential was recorded (Fig. 6). 4. Each sensillum has a typical V shaped tuning curve with the most sensitive sensilla tuned to sound frequencies between 7 kHz and 18 kHz (Figs. 7 and 8). The sensilla of the crista acustica are tonotopically organised with the more proximal receptors tuned to the lower sound frequencies (Figs. 6–8). The frequencies of optimal sensitivity of adjacent sensilla are separated by an interval of approximately 1 kHz (Fig. 8).

The cyto- and fiber architecture of the lateral lobe (LL) of Gymnotus carapo was investigated using Nissl, Golgi and reduced silver stains as well as 1 μ semi-thin sections. The neurons and fiber tracts are distributed in six layers. The first layer is subdivided into two sublayers: 1A where the primary afferent fibers run in rostro-caudal direction and 1B where these fibers terminate and the large multipolar neurons can be found. The 2nd layer consists of a single row of adendritic, pear-shaped neurons. The axons of these neurons enter the 4th layer and leave the lateral lobe in medial direction. The 3rd layer contains the granular cells of two different types: granular cells with two dendritic trunks directed into dorsal and ventral directions respectively, and granular cells in which, instead of the dendritic trunk, the axon emerges from the dorsal pole of the perikaryon. The axon can be followed up to the 6th layer. The 4th layer consists of bundles of nerve fibers. Beside the axons of the pear-shaped neurons the bundles contain also the axons of the pyramidal neurons (5th layer) leaving the lateral lobe. The 5th layer contains the perikarya of the pyramidal neurons. They have two separate dendritic arborizations, one directed ventrally and entering layer 1B and another directed dorsally and penetrating into the 6th layer. Their axons join the 4th layer and run in medial, rostro-medial or rostral direction depending upon the localization of the neurons in the lateral lobe. The 6th layer (crista cerebellaris) consists of three sublayers. Sublayer 6A contains fine myelinated fibers of unknown origin; sublayer 6B contains fine, mainly non-myelinated fibers originating from the mesencephalon, sublayer 6C is built up of non-myelinated fibers originating from the cerebellum. — A preliminary diagram of the neuron circuits and of the synaptic arrangements involved in the relay of lateral-line organ impulses is suggested.

1. The gross anatomical features of the crista acustica in the tettigoniids Mygalopsis marki and Polichne sp. are compared (Fig. 1). The crista in Polichne sp. was longer and contained 12 more receptors than that in M. marki. Both organs, however, displayed a gradual and even taper from the proximal to the distal end. The size of the attachment cells and the length of the sensory dendrites displayed a similar gradual decrease in size from the proximal to the distal end of the array (Fig. 1). 2. The characeristic sound frequency and roll offs in sensitivity of ascending auditory interneurons in the oesophageal connectives of M. marki did not alter after the leg cuticle covering the crista acustica was removed (Fig. 2). Since such interneurons receive excitatory and possible inhibitory input from several receptors in the crista this result indicated that the tuning of these receptors was not affected by removing this portion of the leg cuticle. 3. Physiological recordings were obtained from the cell bodies of individual receptors in the crista acustica of M. marki and Polichne sp. (Fig. 3 A, B). Receptors in M. marki produced a maximum response to an 80 ms tone pulse of 16 spikes/stimulus, had a dynamic range of approximately 30 dB and a rate of increase in the spike response of 6 spikes/10 dB (Fig. 3C). The maximum response, dynamic range and slope of the intensity-response characteristics of auditory receptors in Polichne sp. were less than that for receptors in M. marki (Fig. 3 D). The slope of the intensity response characteristics, dynamic range and maximum spike response of individual auditory receptors in both M. marki and Polichne sp. did not alter for sound frequencies above and below the characteristic frequency of the individual receptor (Fig. 3 C, D). 4. The tonotopic organisation of the crista acustica in M. marki and Polichne sp. was determined by the injection of Lucifer Yellow into the cell bodies and dendrites (Fig. 4 A) of receptors for which the frequency-threshold characteristics had been obtained (Fig. 4B). The characteristic frequencies of adjacent receptors in the crista acustica of M. marki were seperated by irregular amounts with receptor 6 tuned to 7 kHz, receptor 7 to 14 kHz, receptor 8 to 17 kHz and receptors 10 and 11 tuned to 20 kHz (Fig. 6). Although adjacent receptors in Polichne sp. were seperated by approximately 1 kHz, the crista acustica of the species contains four receptors tuned to 20 kHz (Fig. 7). 5. The discontinuities in the tonotopic organisation of the crista acustica of M. marki and Polichne sp. are incompatable with the notion that mechanical resonances within the receptor array could be responsible for the frequency selectivity of these auditory receptors. It is therefore proposed that these receptors are tuned as a result of electrical and/or mechanical resonance intrinsic to the individual sensilla.

Acute hemilabyrinthectomized tadpoles of the Southern Clawed Toad (Xenopus laevis), younger than stage 47 (about 6 days old), perform no static vestibulo-ocular reflex (Fig. 1). Older acute lesioned animals respond with compensatory movements of both eyes during static roll. Their threshold roll angle, however, depends on the developmental stage. For lesioned stages 60 to 64, it is 75 degrees while stage 52 to 56 tadpoles respond even during a lateral roll of 15 degrees (Figs. 1 and 2). Selective destruction of single macula and crista organs revealed that the static vestibulo-ocular reflex is evoked by excitation of the macula utriculi (Figs. 3 and 4) even in young tadpoles. The results demonstrate that bilateral projections of the vestibular apparatus must have developed at the time of occurrence of the static VOR, that during the first week of life the excitation of a single labyrinth is subthreshold (Fig. 1). We discuss the possibility whether the loss of the static VOR during the prometamorphic period of life (Fig. 2) is caused by increasing formation of multimodal connections in the vestibular pathway.

Zusammenfassend last sich sagen, das vor allem Streptomycin, viel weniger dagegen Kanamycin bei direkter Applikation in das Mittelohr und weniger ausgepragt bei intraperitonealer Injektion, zu einer Schadigung der Sinneszellen der Macula des Sacculus und Utriculus sowie der Cristae der Bogengange fuhrt. Die ausgepragtesten Sinneszellverluste fanden sich in der Macula des Utriculus. Die Schadigungen waren besonders ausgepragt im Zentrum der Macula bzw. der Crista. Am meisten betroffen waren die Typ-I-Zellen im Vergleich zu den Typ-II-Zellen, die sich in allen Abschnitten als wesentlich resistenter gegenuber den toxischen Antibiotica erwiesen. An den Stutzzellen waren keine Zeichen einer Schadigung zu erkennen.

The morphology and respiration of liver mitochondria were studied in rats fed with ethanol for eight months. Morphometric analysis shows an increase of the volume fraction of mitochondria, a decrease of the density of crista membranes but the density of surface area remained unaltered in the ethanol treated rats as compared to the controls. The ethanol treatment caused a reduced capacity of the mitochondria to oxidize succinate. The capacity to oxidize α-glycerophosphate remained unchanged.

The macula and crista in the statocyst of Octopus vulgaris are composed of hair cells and supporting cells. Below these cells is a nerve plexus, which contains a third type of cell, the “dark” cell. Each hair cell bears kinocilia and microvilli at its distal end. The kinocilia have the typical 9 + 2 arrangement of filaments and in each cell the cilia are arranged in an elongated group of up to 200. Roots of the kinocilia are present in the hair cells and they have banding periodicity of 700 A. The supporting cells bear microvilli at their distal ends and are attached to the hair cells by desmosomes. The plexus contains the “dark” cells, which appear to send processes throughout the plexus. Synapses have not been found upon their perikaryon or processes and it is suggested that the “dark” cells may be a sort of glial cell. Apart from containing the axons of the hair cells, and the processes and cell bodies of the “dark” cells, the plexus contains synapses. These synapses are of several different sorts. There are synapses at the bases of the hair cells or with their processes. There are spines projecting into the hair cells, the spines being post-synaptic, and there are also other synapses involving processes or axons of cells whose identity is uncertain. The synapses are provisionally grouped as collateral or centrifugal.

A method has been devised for the study of configurational changes in mitochondriain situ during the transition from nonenergized to energized conditions. The method depends upon the following component features: (a) subdivision of the tissue into finely diced sections; (b) the use of a modified Krebs-Ringer phosphate solution as the suspending medium; (c) aerobic conditions as the tactic for imposing the energized state; (d) anaerobic conditions or the presence of uncoupler under aerobic conditions as the tactic for imposing the nonenergized state; and (e) rapid fixation of the diced sections by addition of a mixture of formaldehyde and glutaraldehyde at a controlled temperature. Regardless of the tissue of source (heart, liver, skeletal muscle, retina, kidney) or the species (beef, rat, canary), all mitochondria show unambiguous configurational changes during the transition from nonenergized to energized conditions. The present study has revealed various optional features of the configurational states. Thus, there are two nonenergized configurations of the crista—orthodox and aggregated. The osmotic pressure of the suspending medium determines which nonenergized configuration will be observed. There are at least two variant forms of the energized-twisted configuration—tubular and zigzag. Again the osmotic pressure of the medium is an important factor in determining the form of the crista in the energized-twisted configuration. Mitochondria, such as those of heart muscle with relatively little matrix protein, show the clearest and most regular configurational changes, whereas mitochondria, such as those of liver with an abundance of matrix protein, show a more complex and less regular pattern of configurational change. From this comparative study of mitochondriain situ, it can be concluded that no exceptions have been found to the generalization that changes in configurational state of the cristae accompany changes in the energy state; this exact correlation provides additional support for the hypothesis of the conformational basis of energy transduction in the mitochondrion.

Scanning and transmission electron microscopic studies were performed on the crista ampullaris epithelium of gentamycin treated guinea pigs. 200 μl of a 0.3% solution of the antibiotic was injected once a day through a polythene tube into the middle ear. After seven daily injections various stages of sensory hair degeneration could be observed on the crista surface. The central part of the crista was most severely damaged whereas the periphery of the sides of the crista, as well as the area close to the planum semilunatum, showed less change. The sensory cells of type I were more severely damaged than those of type II. The sensory hairs showed successive stages of fusion. Initially multiple points of contact between neighbouring sensory hairs appeared. Later the plasma membrane disappeared at the points of contact and protoplasmic bridges were formed between the hairs. These bridges increased in length and width until a complete fusion occured between two or more neighbouring hairs. Thus giant hairs were formed. The fusion started close to the cuticle and progressed distally. Balloon-shaped protrusions were then formed into which protoplasm containing cell organelles damaged, to varying extent, was pushed out from the cell. Finally the sensory cell disintegrated and disappeared.

THE semicircular canal is considered classically to be a sensor of angular head motion during animal navigation; however, the functional significance of the canal's morphology and innervation for transduction and encoding of specific head trajectories is unclear. Neural responses from single afferent fibres innervating the crista of isolated elasmobranch labyrinths were used by Groen et al. to determine linear system coefficients of an overdamped pendulum equation, considered to reflect directly the dynamics of the motion of the cupula–endolymphatic fluid in the ampulla1. Similar studies on other preparations revealed certain neural response characteristics that were at variance with simple pendulum models, and these differences were ascribed variously to differences in hair cell physiology and afferent or efferent innervation properties, whose effects were superimposed on the fundamental fluid pendulum dynamics2–4. But in addition to these hypotheses based on cellular influences, the topological organisation of the receptor could result in specific afferent response characteristics deriving from different anatomical regions within the crista. As evidence for the latter, we report diverse classes of afferent responses, describable by distinctly different linear system equations, that are correlated with the position of separate bundles innervating specific areas of the crista of the guitarfish, Rhinobatos productus (Fig. 1).

Formaldehyde-induced fluorescence (Falck-Hillarp technique) provided histochemical evidence for the presence of catecholamines in the sensory epithelia (macula and crista) of the Octopus statocyst. A specific bright green fluorescence occurred in the neuronal plexus beneath the receptor cell layers of the epithelia and in the appropriate nerves. The histochemical findings are discussed with reference to the well-known neuronal and synaptic organization of the epithelia and to relevant results in cephalopods as well as in other molluscs. All data support the hypothesis that in the receptor systems of the Octopus statocyst catecholamines (probably dopamine and/or noradrenaline) act as neurotransmitters in the efferent fibre system.

The conduction velocity and other physiological characteristics of the first order horizontal canal afferents were studied in 24 anesthesized cats. From their spontaneous discharge patterns, neurons were classified into three groups: regular, intermediate and irregular; The irregular units tended to have a low resting rate, high sensitivity to angular acceleration, frequently exhibited adaptation during prolonged acceleration, and showed a short latency from the time of electric stimulation of the labyrinth to recording the action potential near Scarpa's ganglion. The regular units tended to have a high resting discharge rate, low sensitivity, were mostly non-adapting, and showed longer latency to electric stimulation. The intermediate neurons had a mixed character of regular and irregular units. Based on the very short conduction times (mean 0.34 msec) and the work of Moxon (1971), we conclude the locus of activation of electrical stimulation is neural rather than the receptor cells. Since the latency is due predominantly to conduction in the first order axon, and since there is a direct linear relation between conduction velocity and fiber diameter in the medullated nerve fibers, it is possible to speculate that the regular cells have thin fibers which innervate the slope of the crista, the irregular neurons have thick fibers which innervate the summit of the crista, and the intermediate units have medium caliber fibers which innervate both the slope and summit of the crista ampullaris.

Evidence is presented for acetylcholine as neurotransmitter in the sensory epithelia (macula and crista) of the statocyst of Octopus vulgaris, based on the following techniques: (i) histochemical assay of acetylcholinesterase at light- and electron-microscopical levels, in combination with the detailed knowledge of the ultrastructural and neuronal organization of the receptor epithelia; (ii) lesion/degeneration experiments of the efferent fibre system; (iii) radiochemical assay of acetylcholine; and (iv) bioassay of acetylcholine. All data support the hypothesis that in the statocyst of O. vulgaris acetylcholine acts as a neurotransmitter in the efferent fibre system.

YOUNG1 suggests that the three orthogonally arranged sections of the crista of the statocyst of Octopus vulgaris could function as detectors of angular acceleration in a manner similar to the semicircular canals of vertebrates. He also suggests that the macula could provide continuous information about the position of the head. That the statocyst in cephalopods indeed participates in the control of equilibrium and posture has been shown behaviourally2,3. Now we have recorded from the middle cristal nerve of the statocyst the activity of single units of the longitudinal crista that respond unidirectionally to angular acceleration.