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The results of computer simulation of a precision position sensor based on the Foucault knife for automatic focusing of radiation during high-speed laser technological processes are presented, and the results of its implementation and testing at industrial enterprises as part of circular laser recording systems are presented. This sensor is built into laser complexes for microstructuring the surface of optical materials and makes it possible to determine their position with high resolution (the error does not exceed 0.1 µm). [ABSTRACT FROM AUTHOR]

Confocal microscopy study of musculature and other anatomical structures in whole‐mount preparations of arthropods and some other cuticle‐bearing animals often presents a significant difficulty because the cuticle poses a barrier to fluorescent dyes and their pigmented tissues can cause attenuation of fluorescent signal. This paper describes a simple and inexpensive procedure based on the use of clove oil as a tissue‐clearing, staining, and mounting medium that helps overcome the problem of slow dye penetration and tissue opaqueness and allows muscles and several other organ systems to be visualized by confocal or epifluorescent microscopy. This clove oil‐induced fluorescence (COIF) method relies on the ability of clove oil to accumulate in muscles and some other tissues and become steadily fluorescent if irradiated at 488 nm. For this method, animals were fixed in 70% ethanol or 4% formaldehyde, then dehydrated and mounted in clove oil. Heavily pigmented animals were additionally bleached in hydrogen peroxide prior to the dehydration step. The COIF method showed excellent results in all major groups of arthropods and some mollusks and annelids revealing the three‐dimensional arrangement of muscles, gonads, glands, cellular nuclei and some parts of the nervous and digestive systems. In the other animal groups tested, clove oil stained all tissues making it difficult to observe the anatomical details. The COIF method is advantageous in some respects over other methods such as phalloidin staining because of its tissue penetration and clearing abilities, low cost of the reagents, resistance to photodamage and the possibility of staining museum specimens. [ABSTRACT FROM AUTHOR]

The aim of this study was to describe sperm ultrastructure in Segmentinini F.C. Baker, 1945, a tribe of freshwater panpulmonates (Hygrophila), and identify sperm characters that may qualify as candidate synapomorphies of the group. Spermatozoa of seven species representing six genera of Segmentinini were examined by light microscopy and scanning (SEM) and transmission electron microscopy. Sperm ultrastructure is very similar in all species and is generally typical for the Hygrophila. The head consists of a nucleus and conical acrosomal pedestal tipped with an ovoid apical vesicle and is followed by a long midpiece filled with the mitochondrial derivative. The boundary between the midpiece and the next region, the glycogen piece, is marked by a two-partite cylindrical annulus. The glycogen piece is filled with homogeneous mass of glycogen and is followed by a short terminal region, the endpiece. The nucleus has an unusual shape consisting of a barrel-shaped basal region and a narrow apical stem bearing a disc-shaped nuclear keel. The axoneme arises from the centriolar derivative attached to the nucleus with nine wedge-shaped rods. The mitochondrial derivative contains two glycogen-filled helices that spiral apically in opposition to each other, but then become closely apposed and run in parallel. The comparison with other Hygrophila shows that at least three sperm characters (unusual nuclear shape, accessory centriolar rods and arrangement of glycogen helices) can represent potential synapomorphies of the tribe. The shape of the sperm nucleus is readily recognizable by SEM and can be routinely included in taxonomic descriptions of Segmentinini. [ABSTRACT FROM AUTHOR]

The taxonomic position of the Acroloxidae Thiele, 1931 within the Lymnaeoidea Rafinesque, 1815 remains ambiguous. This study is an attempt to evaluate the possibility of using sperm morphology and ultrastructure in resolving the phylogenetic relationships of the Acroloxidae based on a microscopic examination of spermatozoa in Acroloxus lacustris (Linnaeus, 1758), a common Eurasian species, using light, scanning electron and transmission electron microscopy. Acroloxus lacustris, like other Lymnaeoidea, have spermatozoa divided into the head, midpiece, glycogen region and endpiece. The sperm head contains an extremely long nucleus carrying three rounded keels and a cylindrical acrosome composed of an apical vesicle and homogeneously electron‐dense pedestal. The subnuclear ring is an electron‐dense cylinder sandwiched between the basal projection of the nucleus and mitochondrial derivative. The midpiece contains the mitochondrial derivative enclosing apically a single glycogen helix. The spermatozoa have a well‐developed glycogen region and an unusual endpiece with an axoneme anchored on an electron‐dense plaque. Several sperm characters of A. lacustris (solid acrosomal pedestal, rounded nuclear keels, single glycogen helix) differ from those of other Lymnaeoidea possibly representing euthyneuran plesiomorphies. The Acroloxidae may therefore be sister to the remaining Lymnaeoidea, branching off before these gained their characteristic sperm traits. [ABSTRACT FROM AUTHOR]

The larvae of the fresh-water mite Limnochares aquatica (L., 1758) feeding on the pond-skaters Gerris lacustris (L. 1758) and their stylostome were studied using laboratory observations, light-microscope, SEM and TEM methods. The emergence of unfed larvae from the eggshell in the laboratory was also traced. Larvae possess a lamellar area on the ventral surface of the hypostome (supposed sucker or velum), which adheres to the host cuticle during feeding. The bifurcated palpal claws do not pierce the host cuticle and remain outside it during the larval feeding. The larvae secrete at least two saliva portions – the initial one gradually penetrating the host cuticle to which the cheliceral movable digits firmly adhere, and the main one forming the stylostome as such situated underneath the host cuticle. The developed stylostome does not immerse deep into the body cavity and is represented by associations of the uniformly electron-dense globules, the largest of which are pierced by the axial canal. This type of stylostome may be conventionally identified as unclearly ramified structured totally composed of the saliva secretion. The host tissue is partly destructed by the parasite saliva action, and the host defence reaction is imperceptible. The observed stylostome structure may be considered as an initial form for the fresh-water mite branch of the Parasitengona. [ABSTRACT FROM AUTHOR]

In amphipods, the morphology of the mouthparts and digestive system is known to vary according to lifestyle and feeding habits. Since mouthparts are widely used in amphipod taxonomy and the digestive system was also suggested as a source of taxonomic information, it is essential to be able to distinguish between the evolutionary conserved characters of the feeding and digestive apparatus and those influenced by dietary preferences. The opposite side of the same problem is whether the morphology of oral appendages and digestive organs can provide a useful indication of the feeding mode. The present study examined the mouthparts and the digestive apparatus of two common species of Uristidae, Anonyx nugax (Phipps, 1774) and Tmetonyx cicada (Fabricius, 1780), using light and scanning electron microscopy to assess morphological modifications that can reflect the feeding habits and to reveal characters that can be useful for taxonomy. The results show that the mouthparts of A. nugax are modified for shearing and the stomach with reduced lateralia and primary filter are adapted for processing soft muscular tissues suggesting that this species is an obligate scavenger. The morphology of T. cicada is more consistent with the lifestyle of an omnivore and opportunistic scavenger: the mouthparts are adapted both for shearing and grinding and the stomach has functional lateralia and a well-developed secondary filter. The study discusses the characters of potential taxonomic value such as the crater-like structures on the molar and setation on the inner plates of maxillae and maxillipeds. [ABSTRACT FROM AUTHOR]

Abstract This study is the first attempt to describe the ultrastructure and functional morphology of the dermal glands in Limnochares aquatica (L., 1758). The dermal glands were studied using light-optical, SEM and TEM microscopy methods during different stages of their activity. In contrast to the vast majority of other fresh water mites, dermal glands of the studied species are originally multiplied and scattered freely over the mite body surface. The opening of the glands is saddle-like, formed of several tight cuticular folds and oriented freely to the long axis of the mite body. Either a small cuticular spine or, rarely, a slim sensitive seta is placed on one pole of the opening. On the inside, the central gland portion is provided with a complex cuticular helicoid armature. The glands are composed of prismatic cells situated around the intra-alveolar lumen, variously present, and look like a fig-fruit with the basal surface facing the body cavity. The glands are provided with extremely numerous microtubules, frequently arranged in bundles, and totally devoid of synthetic apparatus such as RER cisterns and Golgi bodies. Three states of the gland morphology depending on their functional activity may be recognized: (i) glands without secretion with highly folded cell walls and numerous microtubules within the cytoplasm, (ii) glands with an electron-dense granular secretion in the expanded vacuoles and (iii) glands with the secretion totally extruded presenting giant empty vacuoles bordered with slim cytoplasmic strips on the periphery. Summer specimens usually show the first gland state, whereas winter specimens, conversely, more often demonstrate the second and the third states. This situation may depend on some factors like changes of the seasonal temperature, pH, or oxygenation of the ambient water. On the assumption of the morphological characters, dermal glands may be classified not as secretory but as a special additional excretory organ system of the body cavity. Despite the glands lack cambial cells, restoration of functions after releasing of 'secretion' looks possible. Organization of dermal glands is discussed in comparison to other water mites studied. Highlights • Primitively multiplied dermal glands in a fresh water mite Limnochares aquatica (L., 1758) accumulate waste from the peripheral body cavity. • They play an important role as an additional excretory system of the mite body. • In this course, originally neotrichous body setae are mostly reduced to the orthotrichous type. • Most of the remaining setae are transformed into a fine cuticular spine situated at one pole of the gland orifice. [ABSTRACT FROM AUTHOR]

Although the morphology of spermatozoa has been successfully used in the phylogenetic analysis of various animal groups, its utility for inferring phylogenetic relationships within the Planorbidae s. l. remains limited, because the sperm ultrastructure is currently known in only seven species of this family. The purpose of the present study was to study sperm in Planorbis planorbis (Linnaeus, 1758), the type species of the genus on which the family is based, and Segmentina nitida (O.F. Müller, 1774), and to supplement brief earlier descriptions of sperm in Ancylus fluviatilis O.F. Müller, 1774 and Planorbarius corneus (Linnaeus, 1758). Sperm ultrastructure in these four species is typical for the Hygrophila: the sperm cells are subdivided in an anterior-to-posterior sequence into acrosomal complex, nucleus, midpiece, glycogen piece and free flagellum. The spermatozoa of the four species, however, differ significantly in their total length, the shape and size of the head and nucleus, the shape and structure of the acrosomal complex, the internal structure, arrangement and number of ridges and glycogen helices in the midpiece, the structure of the annulus and the length of the glycogen region. The most morphologically distinct sperm, characterized by a unique flask-shaped nucleus, was found in S. nitida. The study presents a set of potentially phylogenetically useful sperm characters and assesses their usefulness for phylogenetic analysis within the Planorbidae and Hygrophila. [ABSTRACT FROM AUTHOR]

Dermal glands in the water mites Limnesia undulata (O.F. Müller, 1776) and Limnesia fulgida (C.L. Koch, 1836) and their secretion were studied by means of light microscopical, transmission electron microscopical (TEM) and scanning electron microscopical (SEM) methods. These mites possess two types of dermal glands – the ‘common’ dermal glands in a number of 14 pairs and one pair of the so-called ‘idiosomal’ dermal glands. The common dermal glands are bi-lobed organs and consist of high prismatic secretory cells directed to the gland mouth and mostly replacing the intra-alveolar lumen. The cells contain numerous cisterns of rough endoplasmic reticulum (RER) and specifically organized Golgi bodies (GB) producing electron-dense elongated secretory granules. These granules are released from the cells via apocrine secretion and come to the gland mouth, where they are sometimes accompanied by secretory cell cytoplasm. The final secretion may show a fibrous character. The idiosomal glands are sac-like organs stretched along the ventral body wall in posterior direction from the gland orifice corresponding to the epimeroglandularia 4. The secretory epithelium leaves a large intra-alveolar lumen filled with an electron-dense secretory material. Golgi bodies are organized identically with those in the common glands, which indicates the general homology of these two types of dermal glands. The glands' orifices are organized similarly in all glands and possess an internal funnel-shaped sclerite with muscle armament, an internal valve, medial epicuticular flaps and an external circular cuticular ring. All glandularia, except for E4 and V1, are accompanied with a long and thin sensitive seta. During fixation, secretion of the common dermal glands is extruded to the exterior in the form of large amounts of convoluted tube-like structures. In the living organisms, being secreted in mass from the glands, this secretion acquires the form of long rigid mostly hollow un-branched threads comparable with the similar silken threads of other water arthropods. The function of the idiosomal glands secretion still remains unknown. [ABSTRACT FROM AUTHOR]

The intestinal system of unfed fresh-water mite larvae Limnesia maculata (O.F. Müller, 1776) (Acariformes, Limnesiidae) has been studied with transmission electron microscopy. The intestinal system is composed of the foregut, including the pharynx and the esophagus, the sac-like blind midgut and the excretory organ. The pharynx begins with the mouth covered by the labrum. The pharynx runs along the bottom of the gnathosoma and shows ventral dilators. No valves are expressed between the pharynx and the esophagus. The esophagus possesses strongly plicate walls and, before entering the midgut, passes through the brain. The sac-like midgut does not reveal a well-pronounced lumen, developed epithelium and separate lobes. It consists of the two cell types of endoderm origin mixed in the midgut volume. The first type – the vacuolated cells – does not possess Golgi bodies and lysosomal apparatus and shows electron-lucent vacuoles with a granular inclusion inside. These cells apparently do not take part in digestion of the embryonic yolk. The second type – the non-vacuolated cells – shows both, a well developed Golgi complex and large heterolysosomes, and obviously digests the embryonic yolk. Consequently, they may be attributed as specialized vitellophages. Nevertheless, both cell types may take part in formation of the definitive midgut epithelium. The sac-like thin-walled excretory organ is strongly dilated and contains the embryonic wastes in the form of electron-dense globules and birefringent particles. No muscle envelope surrounds the excretory organ. The embryonic wastes together with wastes accumulated during feeding may be evacuated from the organ only after completion of feeding. The excretory canal on this developmental stage is not connected with the excretory organ. It opens to the outside with a simple slit-like excretory pore. Before feeding, larvae have to pass the process of the post-molt development before their midgut would be ready to receive nutrients. • The pharynx runs along the bottom of the gnathosoma and shows both dorsal dilators, constrictors and ventral dilators. • The midgut is composed of two cell types mixed freely – the cells forming the midgut epithelium, and vitellophages. • The sac-like excretory organ contains the embryonic wastes and evacuates them after completion of larval feeding. [ABSTRACT FROM AUTHOR]