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Background The aim of this study was to investigate the fundamental mechanisms of colonic motility in the house musk suncus (Suncus murinus) as an established animal model of gut motility. Methods To measure gut motility in free-moving conscious suncus, strain gauge force transducers were implanted on the serosa of the colon and gastric body. Key results We recorded diurnal changes in colonic motility and observed the relationship between feeding and colonic motility. Giant migrating contractions (GMCs) of the colon were invariably detected during defecation and tended to increase during the dark period, thereby indicating that colonic motility has a circadian rhythm. Given that GMCs in the suncus were observed immediately after feeding during the dark period, we assume the occurrence of a gastrocolic reflex in suncus, similar to that observed in humans and dogs. We also examined the factors that regulate suncus GMCs. Intravenous administration of 5-HT (100 µg/kg), substance P (10 and 100 µg/kg), calcitonin gene-related peptide (10 µg/kg), and α2 adrenergic receptor antagonist yohimbine (0.5, 1, and 3 mg/kg) induced GMC-like contractions, as did intragastric and intracolonic administration of the transient receptor potential vanilloid 1 agonist, capsaicin (1 mg/kg). Conclusions & inferences These results indicate that the fundamental mechanisms of colonic motility in suncus are similar to those in humans and dogs, and we thus propose that suncus could serve as a novel small animal model for studying colonic motility.

Motilin, a 22-amino-acid peptide produced in the upper small intestine, induces strong gastric contraction in fasted state. In many rodents, motilin and its cognate receptors exist as pseudogenes, which has delayed motilin research in the past decades. Recently, the house musk shrew (Suncus murinus) was developed as a useful model for studying motilin and gastrointestinal motility. However, due to a lack of motilin-producing cell lines and difficulties in culturing small intestinal cells, the regulatory mechanisms of motilin secretion and its messenger RNA (mRNA) transcription have remained largely unclear. In this study, we generated small intestinal organoids from S. murinus for the first time. Using methods similar to mouse organoid generation, we found crypt-like budding structures 3 days after isolating intestinal tissues. The organoids grew gradually with time. In addition, the generated organoids were able to be passaged and maintained for 6 months or longer. Motilin messenger RNA (mRNA) and immunopositive cells were observed in both S. murinus intestinal organoids and primary tissues. This is the first report of intestinal organoids in S. murinus, and our results suggest that S. murinus intestinal organoids could be useful for analyzing motilin secretion and transcription.

Background Serotonin (5-hydroxytryptamine, 5-HT) is a regulatory factor in motility of the gastrointestinal tract including the esophagus. Although we proposed that vagal cholinergic and mast cell-derived non-cholinergic components including serotonin coordinately shorten the esophagus, the precise mechanism of serotonin-induced contractions in the suncus esophagus is still unclear. Therefore, the aims of this study were to determine characteristics of contractile responses induced by serotonin and to identify 5-HT receptor subtypes responsible for regulating motility in the suncus esophagus. Methods An isolated segment of the suncus esophagus was placed in an organ bath, and longitudinal or circular mechanical responses were recorded using a force transducer. Key Results Serotonin evoked contractile responses of the suncus esophagus in the longitudinal direction but not in the circular direction. Tetrodotoxin did not affect the serotonin-induced contractions. Pretreatment with a non-selective 5-HT receptor antagonist or double application of 5-HT1 and 5-HT2 receptor antagonists blocked the serotonin-induced contractions. 5-HT1 and 5-HT2 receptor agonists, but not a 5-HT3 receptor agonist, evoked contractile responses in the suncus esophagus. Conclusion & Inferences The findings suggest that serotonin induces contractile responses of the longitudinal smooth muscle in the muscularis mucosae of the suncus esophagus that are mediated via 5-HT1 and 5-HT2 receptors on muscle cells. The serotonin-induced contractions might contribute to esophageal peristalsis and emetic response.

Background: Mouse embryos are cup shaped, but most nonrodent eutherian embryos are disk shaped. Extraembryonic ectoderm (ExEc), which may have essential roles in anterior–posterior (A-P) axis formation in mouse embryos, does not develop in many eutherian embryos. To assess A-P axis formation in eutherians, comparative analyses were made on rabbit, porcine, and Suncus embryos. Results: All embryos examined expressed Nodal initially throughout epiblast and visceral endoderm; its expression became restricted to the posterior region before gastrulation. Anterior visceral endoderm (AVE) genes were expressed in Otx2-positive visceral endoderm, with Dkk1 expression being most anterior. The mouse pattern of AVE formation was conserved in rabbit embryos, but had diverged in porcine and Suncus embryos. No structure that was molecularly equivalent to Bmp-positive ExEc, existed in rabbit or pig embryos. In Suncus embryos, A-P axis was determined at prehatching stage, and these embryos attached to uterine wall at future posterior side. Conclusions: Nodal, but not Bmp, functions in epiblast and visceral endoderm development may be conserved in eutherians. AVE functions may also be conserved, but the pattern of its formation has diverged among eutherians. Roles of BMP and NODAL gradients in AVE formation seem to have been established in a subset of rodents. Developmental Dynamics, 2015. © 2015 Wiley Periodicals, Inc.

Background Rikkunshito (RKT) is a gastroprotective herbal medicine. In this study, we investigated the role of RKT in the relaxation of the gastric body (fundus and corpus) and antrum. Methods We used Suncus murinus, a unique small model animal with similar gastrointestinal motility to humans and dogs. RKT was added at 0.1, 1.0, and 5.0 mg/mL to induce relaxation in vitro; the outcome measure was the intensity of relaxation. The number of spontaneous antral contractions in the absence or the presence of RKT was also counted. Key Results Rikkunshito induced the relaxation of the gastric body and antrum and decreased the number of spontaneous antral contractions in a dose-dependent manner. The responses to RKT (1.0 mg/mL) were not affected by pretreatment with atropine, N-nitro-l-arginine methyl ester, ritanserin, or ondansetron. On the other hand, timolol almost completely reversed the relaxation induced by RKT (1.0 mg/mL) on the gastric body and antrum and the occurrence of the spontaneous antral contractions. Both butoxamine, a β2-adrenoreceptor antagonist, and L 748337, a β3-adrenoreceptor antagonist, but not CGP 20712, a β1-adrenoreceptor antagonist, significantly reversed the RKT-induced (1.0 mg/mL) gastric relaxation. Conclusions & Inferences These results indicate that RKT stimulates and modulates gastric relaxation through β2- and β3-adrenergic, but not β1-adrenergic, pathways in S. murinus.

A common rule for mammals vocalizing in the human audible frequency range (20 Hz–20 kHz) suggests that calls are higher in fundamental frequency (f0) in the young than in adults, because of the smaller soundproducing structures of the young. Exclusions are rare, for example the pups of Asian house shrews (Suncus murinus) make some call types of the same or higher pitch than adults. In this study, calls from 62 piebald shrews (Diplomesodon pulchellum), 37 1 to 10-d-old pups from 10 litters and 25 adults were acoustically investigated in captivity. We found eight call types, all within the human audible frequency range: short and long low-frequency squeaks with nearly flat contour, high-frequency squeaks with modulated contour, high-frequency squeaks with fractured contour, short and long screeches, clicks and whimpers. Seven call types were shared by pups and adults, suggesting that this vocal repertoire commences at birth. Against the common rule, the f0 of squeaks was the same in pups and adults, and the f0 of clicks and screeches was even higher in adults than in pups. These results suggest a non-descending ontogenetic pathway that not follows the common physical relationship, of the lower f0 for the larger vocal folds.

Background and Purpose To understand how anandamide transport inhibition impacts the regulation of nausea and vomiting and the receptor level mechanism of action involved. In light of recent characterization of an anandamide transporter, fatty acid amide hydrolase-1-like anandamide transporter, to provide behavioural support for anandamide cellular reuptake as a facilitated transport process. Experimental Approach The systemic administration of the anandamide transport inhibitor ARN272 ([(4-(5-(4-hydroxy-phenyl)-3,4-diaza-bicyclo[4.4.0]deca-1(6),2,4,7,9-pentaen-2-ylamino)-phenyl)-phenylamino-methanone]) was used to evaluate the prevention of LiCl-induced nausea-induced behaviour (conditioned gaping) in rats, and LiCl-induced emesis in shrews (Suncus murinus). The mechanism of how prolonging anandamide availability acts to regulate nausea in rats was explored by the antagonism of cannabinoid 1 (CB1) receptors with the systemic co-administration of SR141716. Key Results The systemic administration of ARN272 produced a dose-dependent suppression of nausea-induced conditioned gaping in rats, and produced a dose-dependent reduction of vomiting in shrews. The systemic co-administration of SR141716 with ARN272 (at 3.0 mg·kg−1) in rats produced a complete reversal of ARN272-suppressed gaping at 1.0 mg·kg−1. SR141716 alone did not differ from the vehicle solution. Conclusions and Implications These results suggest that anandamide transport inhibition by the compound ARN272 tonically activates CB1 receptors and as such produces a type of indirect agonism to regulate toxin-induced nausea and vomiting. The results also provide behavioural evidence in support of a facilitated transport mechanism used in the cellular reuptake of anandamide.

Background It has been shown in human and canine studies that motilin, a gastroprokinetic hormone, induces gastric phase III contractions via the enteric nervous; however, the center of motilin action in the stomach has not been clearly revealed. In the present study, we investigated the neural pathway of motilin-induced gastric contraction by using Suncus murinus, a new animal model for motilin study. Methods An isolated suncus stomach was used in vitro to determine the mechanism of motilin action through the myenteric plexus. Synthetic suncus motilin (10−11–10−7 mol L−1) was added to an organ bath, and the spontaneous contraction response was expressed as a percent of ACh (10−5 mol L−1) responses. Motilin-induced contractions were also studied by a pharmacological method using several receptor antagonists and enzyme inhibitor. Key Results Suncus motilin induced a concentration-dependent gastric contraction at concentrations from 10−9 to 10−7 mol L−1. The responses to suncus motilin in the stomach were completely abolished by atropine and tetrodotoxin treatment and significantly suppressed by administration of hexamethonium, verapamil, phentolamine, yohimbine, ondansetron, and naloxone, whereas ritanserin, prazosin, timolol, and FK888 did not affect the action of motilin. Additionally, N-nitro l-arginine methylester slightly potentiated the contractions induced by motilin. Conclusions & Inferences The results indicate that motilin directly stimulates and modulates suncus gastric contraction through cholinergic, adrenergic, serotonergic, opioidergic, and NO neurons in the myenteric plexus.

In humans, motion sickness is associated with disruption of normal gastric myoelectric activity, and it has been proposed that this results from an imbalance of autonomic nervous system activity. We used the established Suncus murinus (house musk shrew) model of motion-induced emesis to investigate the effect of horizontal motion on gastric myoelectric activity (recorded using telemetry) and the involvement of the abdominal vagi. Surgical vagotomy increased baseline dysrhythmia and reduced the dominant power of the gastric myoelectric signals. In response to motion, normal gastric myoelectric activity was reduced in sham-operated animals but not in vagotomized animals. Vagotomy, however, failed to affect motion-induced emesis. In conclusion, motion had a differential effect in sham-operated and vagotomized animals, which is consistent with the hypothesis that motion-induced dysrhythmia arises from an autonomic nervous system imbalance.

To gain more insights into the epidemiology of hantaviruses in the coastal region of Zhejiang Province, China, the morbidity and mortality of hemorrhagic fever with renal syndrome (HFRS) were analyzed in two coastal areas: Cixi (hilly terrain) and Wenzhou (mountainous terrain). More HFRS cases have been reported in Cixi than in Wenzhou. Annual incidence rate of HFRS in Cixi had been on the level of approximately 1.5/100,000 from 1968 (when the first HFRS case was reported) to 2007, with the highest incidence rate of 8.54/100,000 in 1999. The annual incidence rate in Wenzhou has been relatively low, less than 0.5/100,000 since the first HFRS case was reported in 1981. A total of 461 rodents and 199 shrews were captured in these two areas. Hantavirus antibodies were detected in 16 of 241 (6.64%) Rattus norvegicus and 13 of 122 (10.66%) R. flavipectus. Interestingly, hantavirus antigens were identified in 6 of 196 (3.06%) Suncus murinus. Genetic analysis showed that partial M and S segment sequences recovered from rats in the two regions belong to Seoul virus (SEOV) and can be assigned into two genetic lineages. SEOV variants that belong to these two lineages of viruses are distributed widely in China and have been found outside China. As most trapped rodents were rats and SEOV was the only hantavirus detected, these results suggested that SEOV plays an important role in human hantavirus infections. They also reinforce the need for vigilance in preventing HFRS caused by hantaviruses in the coastal region.

Summary The occurrence of dermatophytes and other keratinophilic fungi was investigated in 700 small mammals representing 9 species of rodents and one of shrew. Three species of dermatophytes were isolated with an overall prevalence of 16.6%. These included Trichophyton simii (97 isolates), T. mentagrophytes var. granulate (4) and Microsporum gypseum (15). None of the animals yielding dermatophytes showed any skin lesions nor did their hair fluoresce under ultra-violet light. Of the 97 isolates of T. simii, 81 originated from Delhi and 16 from Alwar (Rajasthan). A majority of the isolates of T. simii were obtained from Tatera indica (The Indian gerbil), the dominant field rodent of the plains and peninsular India, and Suncus murinus, a common shrew. The consistent recovery of T. simii from the fur of these animals trapped over a period of 5 years from a particular rural site in Delhi and its association with several other species of small mammals in contrast to its sporadic occurrence in soil suggests that it is predominantly a zoophilic species. The prevalence of other species of keratinophilic fungi in the animals investigated was a follows: Chrysosporium tropicum (3.6 %), C. keratinophvlum (1 %), Keratinophyton terreum (1.7%), Anixiopsis stercoraria (0.4%), Pseudoarachniotus hya-linosporus (0.9 %), Auxarthron zuffianum (0.8 %) and Ctenomyces serratus (0.7 %). Zusammenfassung 700 kleine Saugetiere, 9 Nagetierarten und 1 Spitzmausart einschliesend, wurden auf das Vorkommen von Dermatophyten und anderen keratinophilen Pilzen untersucht. Der Anteil von 3 isolierten Dermatophytenarten betrug 16,6 %. Gezuchtet wurden Trichophyton simii (97 Stamme), Trichophyton mentagrophytes var. granulare (2) und Microsporum gypseum (15).

Background and purpose: Despite the rapid progress made in understanding the significant role played by signalling via extracellular ATP in physiology and pathology, there has been no clear information generated on its involvement in the emetic response. Experimental approach: In the present study, the emetogenic potential of extracellular ATP signalling in mammalian species was examined using ferrets and Suncus murinus (house musk shrews). A slowly degradable ATP analogue, α,β-methyleneATP (α,β-meATP), was used to activate the P2X receptors, and either the non-selective P2 receptor antagonist, pyridoxal phosphate-6-azophenyl-2′,4′-disulphonic acid (PPADS), or the specific P2X3 homomer and P2X2/3 heteromer antagonist, A-317491, were tested against the agonist-induced response. Key results: Intraperitoneal injection of α,β-meATP produced significant emetic responses in ferrets (1 - 30 mg kg−1) and in Suncus murinus (5 - 50 mg kg−1). The responses occurred frequently within the first 10 min after administration, much less frequently from 11 to 60 min and no responses occurred later than 60 min. The emetic responses were completely inhibited by intraperitoneal pre-treatment with PPADS (100 mg kg−1) or A-317491 (100 mg kg−1). Abdominal surgical vagotomy did not reduce the emetic response in Suncus murinus significantly. Conclusions and implications: These results for the first time indicate that the activation of P2X receptors evokes emetic responses in mammalian species. The P2X3 homomer and·or P2X2/3 heteromer in the area postrema could be responsible for the emetic response. This finding contributes to the elucidation of the roles played by extracellular ATP signalling in various emetic symptoms. British Journal of Pharmacology (2007) 152, 464–470; doi:10.1038/sj.bjp.0707418; published online 13 August 2007

The sympathetic cardiac nerves originating from the cervical and upper thoracic sympathetic ganglia in the house musk shrew (Suncus murinus) were examined using macroscopic and whole-mount immunohistochemical methods. Based on the results, the nerves were macroscopically classified into the following three groups: nerves innervating the cervical sympathetic ganglia mainly to the arterial porta of the heart; nerves supplying the stellate and thoracic sympathetic ganglia at the level of T2-T5 or T6 for both the arterial and venous portae of the heart; and nerves innervating the thoracic sympathetic ganglia at the level of T4-T9 to the esophagus and lung and then the heart via the blood vessels within the mediastinal pleura. These findings in the house musk shrew suggest a possible primitive morphological pattern of the cervical and thoracic sympathetic nervous system that may be related to those in other mammals, including humans.

We revealed the structural features of particular synaptic regions, nidi, and newly found neurons, tasseled cells, in the main olfactory bulb (MOB) of the laboratory musk shrew (Suncus murinus). Nidi were intensely immunoreactive for glutamic acid decarboxylase (GAD) and calbindin D28k (CB), were 30-80 microm in diameter, and were located beneath glomeruli, appearing to make glomerulus-nidus unit-like complexes. In contrast to glomeruli, they contained few or no olfactory nerves. Nidi were distributed throughout the whole MOB and made a distinctive layer, nidal layer. Tasseled cells were located in the mitral cell layer and in the middle of the external plexiform layer (EPL) and extended single primary dendrites to the nidus, where their small tuft-like complicated branches intermingled with processes of perinidal cells surrounding nidi. Primary dendrites of mitral/tufted cells also penetrated nidi but passed to glomeruli. In the outer half of the EPL, columnar structures were seen, where CB- and GAD-positive elements appeared to associate with bundles of cylindrical dendrites of presumed mitral/tufted and tasseled cells. By electron microscopic examinations, nidi were confirmed to be particular synaptic areas where GAD-positive processes made symmetrical synapses to GAD-negative presumed tasseled and mitral/tufted cell dendrites and received asymmetrical synapses from the latter. Retrograde tracings revealed that tasseled cells, in addition to mitral/tufted cells, projected their axons to the lateral olfactory tract, indicating that there were two parallel projection systems in the shrew MOB, which might interact with each other via various types of gamma-aminobutyric acid (GABA)ergic interneurons. The present study clearly showed that the neuronal organization of the shrew MOB was distinctly different from that in rodents.

In Suncus murinus the ultrapotent capsaicin analogue resiniferatoxin (RTX) induced an emetic response in the dose range 1–1000 μg kg−1, s.c. The latency was inversely related to dose and ranged from 41.2±4.4 min. (1 μg kg−1, s.c.) to 2.7±0.6 min. (1000 μg kg−1, s.c.). The emetic response to RTX (10 or 100 μg kg−1, s.c.) was blocked or markedly reduced by pre-treatment with RTX (100 μg kg−1, s.c.), 8-OH-DPAT (100 μg kg−1, s.c.), morphine (2 mg kg−1, s.c.), neonatal capsaicin (100 mg kg−1, s.c.) and the NK1 receptor antagonist CP-99,994 (10–20 mg kg−1, s.c.) but not by the 5-HT3 receptor antagonist tropisetron (200 μg kg−1, s.c.). RTX (100 μg kg−1, s.c.) induced c-fos-like immunoreactivity in the area postrema and parts of the nucleus tractus solitarius. This pattern is consistent with the proposal that the emetic effect is mediated via one or both of these structures and an involvement of substance P is discussed. RTX (10 and 100 μg kg−1, s.c.) had broad-spectrum antiemetic effects in Suncus as indicated by its ability to block or markedly reduce the emetic response to motion (1 Hz, 4 cm lateral, 10 min.), cisplatin (20 mg kg−1, i.p.), intragastric copper sulphate (40 mg kg−1, p.o.), nicotine (10 mg kg−1, s.c.) and RTX (100 μg kg−1, s.c.) itself. It is proposed that the site of the anti-emetic effect is in the nucleus tractus solitarius and mechanisms involving the modulation of substance P release are discussed. The general utility of Suncus for investigations of vanilloid receptors is reviewed in the light of the exquisite sensitivity of the emetic reflex in this species to resiniferatoxin. British Journal of Pharmacology (2000) 130, 1247–1254; doi:10.1038/sj.bjp.0703428

Fleas on the body surface of a certain species of small mammal form a special flea community. On the basis of a series of calculations, a comparison of flea communities on ten species of small mammals in the foci of human plague in Yunnan Province, China, was carried out through a fuzzy clustering analysis. The three flea communities on Rattus flavipectus, Rattus nitidus and Rattus rattus sladeni, which belong to the same genus (genus Rattus) showed a higher similarity than others and they clustered into a group in the phenogram of the clustering analysis. Other flea communities on Anourosorez squamipes Suncus murinus Crocidura attenuata Apodemus draca Eothenomys eleusis, Niviventer confucianus and Mus pahari showed lower similarities between each other. The result suggests that the small mammal hosts may be the most important factor which strongly influence the similarity of ectoparasitic flea communities. When the hosts have a close affinity in the taxonomy, the flea communities on their body surface tend to be similar. The hosts in different genera in this case study tend to have different types of ectoparasitic flea communities.

A small mammal survey of the Lipotyphla (Tenrecidae and Soricidae) was conducted in the montane forest of the Reserve Speciale d'Ambohitantely, Central High Plateau, Madagascar. Species richness of this group was assessed using standardized pit-fall trap techniques in a control site of 1250 ha and four smaller forest fragments (136, 30, 12 and 0.64 ha). The forests of this reserve are highly fragmented, isolated for many decades and about 90 km from the nearest large forest block. On the basis of pit-fall captures, lipotyphlan diversity was highest in the control site with nine species, including eight endemic taxa. The number of species declined progressively with diminishing forest size. The species richness found in the control site, the largest remaining block within the reserve, is comparable to other much more extensive forest blocks at parallel elevations and with similar botanical communities. Thus, it seems that the lipotyphlan community within the control site has not experienced notable local extinctions. The introduced Soricidae, Suncus murinus, has colonized the Ambohitantely forests. However, there is no evidence of competition between this species and members of the family Tenrecidae, particularly Microgale, as has been postulated in the literature.

Glycosphingolipids were extracted from the brain of house musk shrew (Suncus murinus). Neutral glycosphingolipids were purified by QAE-Sephadex column chromatography followed by high-perfor-mance liquid chromatography using an Iatrobeads column. Purified glycosphingolipids were identified by high-performance thin-layer chromatography, carbohydrate analysis, fast-atom bombardment mass spectrometry and TLC immunostaining. The ganglioside pattern was almost the same as the pattern obtained for rat brain gangliosides. The brain of S. murinus, however, was unique in its neutral glyco-sphingolipid composition; it contained gangliotriaosylceramide and gangliotetraosylceramide as the major neutral glycosphingolipids in addition to monohexosylceramides. Mass spectroscopy analysis showed that C18: 1 sphingosine and C24:O normal fatty acids were the major ceramide constituents in the glycosphin-golipis, except in the case where a slower-migrating monohexosylceramide that contained C24 h: 0 hy-droxy fatty acids was observed. A day after birth, monohexosylceramide contained only normal fatty acids. The amounts of hydroxy-fatty-acid-containing monohexosylceramide increased rapidly as the age of the animals increased, and the ratio of these two kinds of monohexosylceramides was reversed within five weeks. Monohexosylceramide, ganglioside, and sulfatide contents in bulbus olfactorius were almost equal in amount in contrast to the glycolipids in the cerebrum and cerebellum that contained monohexosylceramide as the major constituent. The amount of monohexosylceramide in the bulbus olfactorius was 0.3–0.4 times the values obtained for the of cerebrum and cerebellum.

1. The effects of (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOl), a 5-hydroxytryptamine 5-HT2A/5-HT2C receptor agonist, on motion- and cisplatin-induced emesis were studied in Suncus murinus. Subcutaneous injection of DOl, 30 min prior to the emetic stimuli, dose-dependently blocked the emesis induced by motion sickness and cisplatin (20 mg kg-1, i.p.) with estimated ID50 values of 640 and 780 micrograms kg-1, respectively. 2. alpha-Methyl-5-hydroxytryptamine (alpha-Me-5-HT), a peripheral 5-HT2A/5-HT2C receptor agonist, had no effect on motion- and cisplatin-induced emesis. 3. The antiemetic effects of DOl on motion- and cisplatin-induced emesis were attenuated by preadministration of ketanserin, a selective 5-HT2A receptor antagonist. 4. The present results suggest an inhibitory role for central 5-HT2 receptors in the emetic reflex mechanism and that a 5-HT2 receptor agonist may be a useful tool to investigate the involvement of 5-HT receptors in the emetic reflex.

The histological changes occurring in the esophageal mucosa of shrews (Suncus murinus) after N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) treatment were investigated sequentially. Six-week-old female shrews were given a 50 micrograms/ml MNNG solution as drinking water for 30 weeks, and 5 selected at random were killed at 10 and 20 weeks of age, and thereafter at 5-week intervals until 45 weeks of age. Controls were killed at 45 weeks of age. The MNNG-induced esophageal lesion in shrews began from basal cell hyperplasia at 20 weeks of age, followed by dysplasia occurring at 25 weeks of age, then progressed toward intraepithelial carcinoma to invasive squamous cell carcinoma at 35 weeks of age. Apparent sequential dysplasia-carcinoma transition was seen. Papillomas were seen from 25 weeks of age but there was no evidence of papilloma-carcinoma sequence. Five MNNG-untreated shrews killed at the end of the experiment were free of esophageal tumors.

Eosinophilopoiesis in the musk shrew, Suncus murinus, a representative of the order Insectivora, was studied by light and electron microscopy. To examine biochemical features of cytoplasmic granules, extraction with proteolytic enzymes was carried out on ultrathin sections of bone marrow. In this species, eosinophils are produced in the same manner in both spleen and bone marrow. Developing eosinophils were distinguished as belonging to four stages, recognized by ultrastructural changes in cytoplasmic organelles as well as the eosinophilic granules during maturation. Granulogenesis began by budding of vacuoles containing flocculent material from the concave face of the Golgi apparatus, in the promyelocyte to myelocyte stage. The matrix of developing granules transformed into a finely granular structure, and the large spherical granules of mature eosinophils were homogeneous without crystalline cores. It was shown by proteolytic enzyme extraction that the proteinaceous cores of mature granules were uniformly removed; there was no evidence that they contained crystalloid inclusions. These results indicate that shrew eosinophils can be regarded as cells that retain a prototype of eosinophil granules, probably like those of ancestral mammals rather than those of higher living Mammalia.

Prolactin-secreting cells (PRL cells) in the anterior pituitary gland of the female musk shrew were identified by the protein A—gold procedure combined with electron microscopy. Their secretory granules were spherical, and showed variuos sizes ranging in diameter from 100 nm to 800 nm according to the difference in physiological conditions of the animals. In pregnant and lactating animals, the PRL cells exhibited morphologically active features, i.e., a large prominent Golgi apparatus and a well-developed rough endoplasmic reticulum (RER) consisting of densely packed parallel lamellae. In pregnant and estrogen-treated animals, the secretory granules of PRL cells significantly increased in size as compared with those of virgin animals. The most remarkable ultrastructural change observed in PRL cells of pregnant, lactating, and estrogen-treated female musk shrews was the occurrence of “intracisternal” granules. They were small and spherical, and were located without limiting membranes inside the dilated cisternae of the RER. Intracisternal granules, as well as ordinary secretory granules, were found to be immunoreactive for PRL by the protein A—gold procedure. These results suggest that PRL cells of the female musk shrew may possibly utilize a “bypass” route to form hormone-containing granules under highly activated cellular conditions.

The development of the small intestine in the insectivore Suncus murinus was noted during the period from 21 days' gestation to 20 days after birth. At 21 days of gestation, the proximal small intestine exhibited the beginning of villus formation, whereas the distal small intestine preserved the stratified epithelium. Stratified epithelium in the distal small intestine changed into a single layer by 24 days' gestation. At 26 days' gestation, each epithelial cell was immature; but by 28 days mature-looking epithelial cells were found. The shape of the villi changed from cuboid to columnar during the same period. The connective-tissue cores of the villi began to develop at 7 days after birth in the proximal small intestine and at 15 days after birth in the distal small intestine. Crypts appeared at 15 days after birth. Endocytosis of epithelial cells took place at 28 days of gestation. In the proximal small intestine, supranuclear vesicle clusters were observed first at birth; they began to decrease both in number and size at 10 days' gestation and then disappeared completely by 20 days after birth. In the distal small intestine, large supranuclear vacuoles were observed first at 28 days of gestation. Although these vacuoles invariably were found up to 15 days after birth, they also disappeared completely by 20 days. Epithelial cells showed a structure similar to those of the adult after weaning.

The structure of the liver of the thick-tailed shrew (Suncus murinus) was studied with special reference to the vitamin A-storing cell. The macroscopic arrangement of hepatic lobes was the same as those of rodents. Connective tissues of Glisson's sheath were not prominent. There were gradual differences in the size and the cytoplasmic contents of hepatocytes among perihepatic, intermediate, and periportal regions. These correspond to the acinar zones 3, 2, and 1 of Rappaport, respectively. The ultrastructural features of the hepatocyte were numerous microvilli, a large mass of glycogen particles (α-particles), and well-developed Golgi complexes and lysosomes in the peribiliary region. Cellular elements of the sinusoid were the same as those of rodents. Vitamin A-storing cells were demonstrated by autoradiography of tritiated retinyl acetate administered orally. They were distributed in the perihepatic and intermediate regions. The number of vitamin A-storing cells was much smaller than that in the mouse liver and did not increase after excess vitamin A was given to the animal. Cytological features of the vitamin A-storing cells in Suncus liver were similar to those for other mammalian livers. The scarceness of vitamin A-storing cells and the low amount of vitamin A esters suggest that Suncus does not store much vitamin A in the liver.

High-speed cinematography shows that Suncus murinus (Crocidurinae) masticates fast (mean 5.5, 5-10 masticatory cycles per sec). Their grasping behavior is not stereotyped. The unilateral mandibular movements combine vertical, anteroposterior, and lateral displacements; and any masticatory sequence may include crushing, repositioning, shearing, and grinding components. Size and consistency of food influence the duration of individual chewing cycles. As food is transferred to the new working side, the chewing direction reverses, either near maximum closure or near maximum opening. An unfused mandibular symphysis permits tilting movements of the two halves of the mandible. Food may be squeezed between the lower incisors. The working side tilts outward during closing; this may improve shearing or grinding action. The closing phase is posteriorly directed. Thus, the masticatory movements of these shrews differ from those that have been described in many other mammals.

Lipid droplets discharged from the disintegrating holocrine cells of the flank gland of the Indian musk shrew, Suncus murinus viridescens (Blyth) are stored in the lumen of the sebaceous acini and eliminated to the exterior through the glandular ducts. Specialized hairs developed on the surface of the flank gland of the shrew are deep rooted. The osmetrichia of the flank gland of both sexes of the shrew have flattened and thickly packed culicular scales. These scales are morphologically different from the largeconical-shaped scales of the dorsal body hairs. The surface of osmetrichia is soaked with the oily secretory materials of the flank gland. The medulla of osmetrichia is developed into Special chambers which are filled with the glandular secretory droplets.

The fine structure of spermatozoa of the Asian musk shrew, Suncus murinus, has been investigated using air-dried and critical-point-dried replicas in addition to freeze-fractured specimens. Asymmetry in the structure of the head, notable the acrosome, can be recognized in critical-point-dried replicas as a slight dorsoventral convexity not apparent in air-dried specimens. Freeze-etching reveals a dense accumulation of intramembranous particles just anterior to the posterior ring, but relatively few other characteristic membrane conformations associated with the head. Gelatin smears visualized with the light microscope show a vigorous lytic response, but preliminary efforts to remove the acrosome by physiological or enzymatic incubation have thus far not been successful.

Data on various features influencing resource acquisition and allocation of energy in Soricidae are reviewed. The relationships between these features are examined at the three functional levels that constrain the energetic design of shrews: the maintenance of homeostasis (rate of metabolism and temperature regulation), the balancing of the energy budget (e.g. the influence of body mass, activity rate, various energy saving mechanisms and home range size), and the allocation of energy towards reproduction (e.g. the influence of litter size). Two major contradictory energetic designs may be recognized: one rather expensive design that is observed in cold and temperate climates with relatively predictable fluctuations in resource availability (e.g. in Sorex and Neomys), and another much less expensive design that is observed mainly in warm or unpredictable environments (e.g. in Crocidura, Suncus and Notiosorex). It is speculated that climate and resource availability impose narrow limits on the evolution of these energetic strategies, mainly because of the small thermal inertia and reduced energetic autonomy of shrews.

The epidermal growth factor (EGF) from the submaxillary glands of the Chinese Shrew (Suncus murinus) is purified to apparent homogeneity by using a sequence of four chromatographic steps, viz. gel filtration on Sephacryl S-200, affinity chromatography on immobilized Ni, hydrophobic interaction on phenyl-Sepharose CL-4B and reverse-phase HPLC. An 800-fold increase in specific activity and an overal recovery of 46% were achieved. The most effective step in its purification is the successful use of immobilized metal ion affinity chromatography (IMAC). This method was very selective, reproducible and requires a minimum of sample pre-treatment prior to chromatography.