Combined oral contraceptives promote androgen receptor and oestrogen receptor alpha upregulation in the female prostate (Skene's paraurethral glands) of adult gerbils (Meriones unguiculatus).

The aim of this study was to evaluate the effects of cyproterone acetate (CPA) and ethinyloestradiol (EE) alone or in combination on the female prostate of adult gerbils. Adult females were exposed for 21 days to daily oral doses of CPA (1mgkg-1), EE (10µgkg-1) or a combination of CPA and EE. Female prostatic complexes were removed, weighed and subjected to morphological, stereological, immunohistochemical and ultrastructural analyses. CPA treatment caused epithelial atrophy and decreased prostate secretory activity. The EE treatment group showed glandular hyperplasia, a high cell-proliferation index and an increase in androgen and oestrogen receptor α (AR and ERα) immunoreactivity. Combined treatment (CPA+EE) caused adverse effects, such as an increase in cell proliferation, higher AR and ERα immunoreactivity, prostatic intraepithelial neoplasia, cell degeneration and aging. In conclusion, the CPA-only treatment promoted antiandrogenic effects on the female gerbil prostate, whereas EE-only had a potent oestrogenic activity. However, when combined, EE overlapped the effects of CPA, changing the pattern of glandular hormonal regulation and stimulating the development of prostatic lesions in female gerbils.

Seasonal morphophysiological variations in the prostatic complex of the Tarabul's gerbil (Gerbillus tarabuli).

Gerbillus tarabuli is a nocturnal Saharan rodent which has an annual reproductive cycle characterized by the reproductive activity in spring and a long phase of sexual quiescence in other seasons. We describe the morphology and hormonal regulation of the prostatic complex of this rodent in the two periods, based on anatomical, histological, morphometric, and immunohistochemical analyses. The organisation of this prostatic complex is similar to that reported for Meriones unguiculatus, but different from the prostate of Psammomys obesus, the rat, and the mouse. In addition to the anterior lobes, ventral lobes, and dorsal lobes, the prostatic complex of Gerbillus tarabuli, also includes dorsolateral lobe. Each lobe is composed of a fibro-muscular stroma surrounding a glandular epithelium. Dorsolateral lobes are easily distinguishable by their big volume. The prostate grows and regresses cyclically throughout the year. During the resting season, ventral lobes and anterior lobes showed atrophy, with a significant decrease in both epithelial height and supranuclear area size, and a strong thickening of the fibro-muscular compartment. In dorsal lobes, the epithelial and stromal compartments atrophied and regenerated simultaneously, whereas in dorsolateral lobe the thickness of the epithelium, the supranuclear zone and the stroma increased during resting period. Furthermore, seasonal variations were observed in the distribution and expression of both androgen receptors, and estrogens receptors. Expression patterns of all receptors were lobe-specific. In conclusion, both androgens and estrogens are involved in the homeostasis and regulation of the prostate in Gerbillus tarabuli. Dorsolateral lobe seems to be controlled by a different mechanism than other lobes.

Histological and immunohistochemical characterization of the Mongolian gerbil's mammary gland during gestation, lactation and involution.

The morphological description of normal tissues is fundamental for making comparisons and in order to identify injuries and lesions. The aim of this work was to describe the morphological characteristics of the female Mongolian gerbil's (Meriones unguiculatus) normal mammary gland, the average expression of hormone receptors, and the average proliferation rates in the epithelial cells during the periods of lactation, pregnancy and involution. Dams were euthanized on the 14th and 21st gestational days, 7 and 14days after parturition, and 3 and 5days after weaning. The dams' mammary tissues were processed and were submitted to haematoxylin and eosin staining, Periodic Acid Schiff (PAS) staining, and Gomori's Reticulin staining. Additionally, immunohistochemistry was performed for the characterization of myoepithelial cells with α-actin, the proliferation rates with proliferating cell nuclear antigen (PCNA), the estrogen hormonal receptors (ESR1 and ESR2), and progesterone receptor (PR) quantifications. It was observed that the abundant adipose tissues were replaced by glandular epithelia and there was an increase in the epithelial cell's height (from 5.97 to 32.4µm in 14th and 21st gestational days and from 20.64 to 25.4µm in 7th and 14th lactational days, respectively) and the acini diameters (from 24.88 to 69.92µm in 14th and 21st gestational days and from 139.69 to 118.59µm in 7th and 14th lactational days, respectively) with the progression of gestation and lactation. The PAS staining intensity varied throughout the glands and between the stages that were evaluated. The extracellular matrix showed different phenotypes too, with more of a presence of the Type I collagen during the early gestation and involution and with more reticular fibers (Type III collagen) during the late gestation period and lactation. The myoepithelial layers showed alterations in their distribution with thick patterns as verified by the α-actin labeling. The PCNA showed higher rates of the marked cells in 14th and 21st gestational days (40.25 and 60.28%) and in 7th and 14th lactational days (64.08 and 65.08%). The hormone receptor quantifications showed a high variation in the rates: the average PR staining decreased from 14th to 21st gestational days (from 42.3 to 8.54%), from 7th to 14th lactational days (from 59.83 to 23.18%) and from 3rd to 5th days after weaning (from 39.98 to 12.72). There were higher averages of ESR1 staining in gestational days 14 and 21(from 58.06 to 30.02%). ESR2 staining decreased during gestation (25.7 and 12.94% in 14th and 21st gestational days)and involution (from 50.97 to 30.18% in 3rd and 5th days after weaning). The Mongolian gerbils showed similar morphological characteristics when they were compared to mice and rats. However, the higher proliferation rates with a smaller involution period compared to other murine characterized this species as being adequate for mammary pathologies studies.

Morphology and ciliary motion of mucosa in the Eustachian tube of neonatal and adult gerbils.

The Eustachian tube is a small canal that connects the tympanic cavity with the nasal part of the pharynx. The epithelial lining of the Eustachian tube contains a ciliated columnar epithelium at the tympanic cavity and a pseudostratified, ciliated columnar epithelium with goblet cells near the pharynx. The tube serves to equalize air pressure across the eardrum and drains mucus away from the middle ear into the nasopharynx. Blockage of the Eustachian tube is the most common cause of all forms of otitis media, which is common in children. In the present study, we examined the epithelial lining of the Eustachian tube in neonatal and adult gerbils, with a focus on the morphological and functional development of ciliated cells in the mucosa. The length of the tube is ∼8.8 mm in adult gerbils. Scanning electron microscopy showed that the mucosal member near the pharyngeal side contains a higher density of ciliated cells and goblet cells than that near the tympanic side. The cilia beat frequency is 11 Hz. During development, the length of the Eustachian tube increased significantly between postnatal day 1 (P1) and P18. Scanning electron microscopy showed that the mucosa contained a high density of ciliated cells with a few goblet cells at P1. The density of ciliated cells decreased while the density of goblet cells increased during development. At P18, the mucosa appeared to be adult-like. Interestingly, the ciliary beat frequency measured from ciliated cells at P1 was not statistically different from that measured from adult animals. Our study suggests that the Eustachian tube undergoes significant anatomical and histological changes between P1 and P18. The tube is morphologically and functionally mature at P18, when the auditory function (sensitivity and frequency selectivity) is mature in this species.

Effects of exposure to estradiol and estradiol plus testosterone on the Mongolian gerbil (Meriones unguiculatus) female prostate.

The female prostate is a differentiated organ found in several mammal species, including humans and rodents. This gland has been related to important functions on female reproductive biology. Although the factors, which regulate prostate's development and activity are not well known, its functionality has been related to steroid hormones. It is well established that cyclic changes of estradiol and progesterone levels promote histophysiological adaptations of the whole female body. In contrast, only a few is found about those adaptations in female prostate. Thus, this study aimed to evaluate the effect of estradiol and estradiol + testosterone association on gerbil female prostate in order to verify, which hormonal associations are necessary to its homeostasis. For this, adult females had the ovaries surgically removed. After recovering, they received estradiol and estradiol + testosterone doses through 30 days, each 48 h. The prostatic tissue underwent morphological and morphometric-estereological analysis. Hormonal restriction caused great gland involution and decreased secretory activity, aspects that were reverted by exposure to estradiol and estradiol + testosterone. However, these hormones were not able to re-establish the normal prostate histoarchitecture. The immunoreaction of steroid receptors (ER-α, ER-ß, and AR) responded differently among the experimental and control groups, and PCNA assay showed a decrease in epithelial cell proliferation within groups that had hormone privation. Therefore, we conclude that estradiol and testosterone are able to influence prostate morphophysiology and the maintenance of gland homeostasis depends on a balance among these and other hormones.

Pituitary adenylate cyclase-activating polypeptide-immunoreactive cells in the ageing gerbil hippocampus.

In the present study, we investigated age-related changes in pituitary adenylate cyclase-activating polypeptide (PACAP) immunoreactivity and its protein levels in the gerbil hippocampus at various ages using immunohistochemistry and western blot analysis. In the post-natal month 1 (PM 1) group, PACAP-immunoreactive cells were found in all hippocampal subregions. The number of PACAP-immunoreactive cells was decreased in the PM 3 group and was still more decreased in the PM 6 and 12 groups. Thereafter, in the PM 18 and 24 groups, PACAP-immunoreactive cells were significantly increased again. However, in the mossy fibre zone, PACAP immunostaining was very strong in the adult group, especially in the PM 6 group. In addition, PACAP protein level was highest at PM 6, showing a slight decrease at PM 24. These results indicate that PACAP-immunoreactive cells are lowest in the adult stage and highest in the aged stage. However, PACAP immunoreactivity in the mossy fibre zone and PACAP protein level in the hippocampus are highest in the adult stage.

Nitric oxidergic cells related to ejaculation in gerbil forebrain contain androgen receptor and respond to testosterone.

Two clusters of forebrain neurons-one in the posterodorsal preoptic nucleus (PdPN) and one in the lateral part of the posterodorsal medial amygdala (MeApd)-are activated at ejaculation in male rats and gerbils as seen with Fos immunocytochemistry. To understand the functions of these cells and how they respond synchronously, it may be useful to identify their neurotransmitters. Nitric oxide (NO) was of interest because its levels in the preoptic area affect ejaculation, and it could synchronize clustered neurons through paracrine/volume transmission. Thus, we determined whether the ejaculation-related cells produce NO by assessing Fos co-localization with NO synthase (NOS) in recently mated male gerbils. We also studied NOS-Fos co-localization in the medial part of the medial preoptic nucleus (MPNm), where half of the neurons that express Fos after mating reflect ejaculation. We also quantified NOS co-localization with androgen receptor (AR) and NOS sensitivity to androgens at these sites. Without quantification, we extended these analyses throughout the hypothalamus and amygdala. Many mating-activated PdPN, lateral MeApd, and MPNm cells contained NOS (32-54%), and many NOS neurons at these sites expressed Fos (34-51%) or AR (25-69%). PdPN and MPNm NOS cells were sensitive to testosterone but not its androgenic metabolite dihydrotestosterone. The overall distribution of NOS and NOS-AR cells was similar to that in rats. These data suggest that NO may help to synchronize the activation of PdPN and lateral MeApd neurons at ejaculation and that NOS in PdPN and MPNm cells is regulated by testosterone acting via estradiol or without undergoing metabolism.

The morphology of islets of Langerhans is only mildly affected by the lack of Pdx-1 in the pancreas of adult Meriones jirds.

The Meriones Jirds belong to the genus of Gerbillinae (Rodentia: Muridae). We and others have previously reported the lack of the pancreatic beta-cell transcription factor, Pdx-1 in the fat sand rat, Psammomys obesus. The aim of the study was to investigate the expression and localization of Pdx-1 in phylogenetically related members of the Gerbillinae subfamily. In addition, we characterized by IHC the expression pattern of islet hormones and additional important pancreatic transcription factors in order to evaluate overall endocrine pancreas appearance. PCR showed that Pdx-1 was easily amplified from a wide range of phylogenetically distant species but not from 13 different gerbilline species. Identical to P. obesus the important beta-cell transcription factor Pdx-1 was absent from all five jirds. However, expression of other critical islet transcription factors and islet hormones was generally normal. Insulin was localized in the center of the islets with glucagon, somatostatin and pancreatic polypeptide (PP) found in the islet mantle. PYY cells were also observed and colocalized with PP cells. The NKX family of transcription factors were localized to the same cell types as seen in other rodents. MafA was nuclear localized in some of the insulin immunoreactive but not in other cell types, while MafB was found not only in the glucagon cells but also in many of the insulin cells. In conclusion, Pdx-1 appears to be lacking in all gerbils and despite the lack of Pdx-1, the Meriones Jirds have islets that are morphologically similar to other rodents and express hormones and transcription factors in the expected pattern except for MafA and MafB.

Morphological and histological effects on the medial pterygoid muscle after unilateral exodontia in gerbils.

Morphological effects on the medial pterygoid muscle were evaluated in 20 male gerbils (average weight, 55 g) after occlusal alterations induced by extraction of left side molar teeth. Controls were only submitted to surgical stress. Sixty days after surgery, the groups were divided into two subgroups for the following studies: (1) observation of macroscopic morphology and vessels distribution (n=10); (2) light microscopy histological analysis (n=10). Group results were statistically compared using the Wilcoxon and Mann-Whitney tests, with a significant value of p<0.05. Statistical differences in biometric data were found between the left and right sides of the experimental group (p=0.043), and between the left side of the control group when compared to the same side in the experimental group (p=0.044). Vessels supplied by bundles of the external carotid artery in the medial pterygoid muscle did not show distribution differences in group comparisons. Histological alterations were found in the ipsilateral side of the experimental group, with a central localization of the nucleus and degenerative aspect of the fibers, usually near to internal aponeurosis. Fiber diameters seemed reduced and the neuromuscular spindles were localized near internal aponeurosis and had a modified appearance. It is concluded that the medial pterygoid muscle in the gerbil is sensitive to alterations of the masticatory movements.

Vertebral endplate and disc changes in the aging sand rat lumbar spine: cross-sectional analyses of a large male and female population.

STUDY DESIGN: Lumbar vertebral segments from a large cross-sectional population of male and female sand rats were assessed for quantitative determination of lumbar endplate bone mineral density (BMD) and radiologic features. OBJECTIVE: To determine radiologic and BMD characteristics in the lumbar spines of males and females ranging in age from 1.5 to 46.0 months. SUMMARY OF BACKGROUND DATA: The sand rat provides an excellent economical model in which disc degeneration is reliable and well characterized. A major advantage of this model is that disc degeneration is spontaneous and does not need to be induced by stab surgical procedures. Previous work has only examined a small group of male sand rats for radiologic and BMD features of the lumbar spine; more complete data on both genders and a wider age range are lacking. METHODS: BMD data were obtained for 99 male or female sand rats aged 1.5 to 46.0 months using the GE Lunar PIXImus bone densitometer; results were assessed for changes related to age, weight, gender, lumbar vertebral site, and radiologic characteristics of disc degeneration (disc space narrowing, wedging, and endplate calcification). Four age groups were studied: Group 1, 1 to 3.9 months of age; Group 2, 4 to 11.9 months of age; Group 3, 12 to 23.9 months of age, and Group 4, 24 to 46 months of age. RESULTS: Group 1 females showed a greater incidence of radiologic disc space narrowing and wedging at L1-L2, L2-L3, L3-L4, L4-L5, and of wedging at sites L5-L6, L6-L7, and L7-S. Group 2 females had significantly greater disc space narrowing at L3-L4 and L4-L5. By the time animals reached the age of Groups 3 and 4, males showed more wedging at L1-L2 and L3-L4. BMD data showed that Group 1 females had significantly lower BMD than Groups 2, 3 and 4 at all lumbar levels, and Group 4 had significantly higher BMD than Group 3. For males, there were no differences in younger animals, but older Group 3 and 4 animals had significantly greater BMD than Groups 1 and 2. Caudal BMD values were generally significantly higher than cranial values. Averaged BMD levels correlated significantly with both age and body weight, but the correlation with age at each lumbar level accounted for much more of the variation than did weight. Averaged BMD was significantly greater in disc sites showing disc space narrowing than in sites without narrowing for L1-L2 and L3-L4 through L7-S (P < or = 0.002 for each spinal level). CONCLUSION: Results expand our understanding of the association of age and gender to endplate sclerosis patterns in the lumbar spine, and support the hypothesis that endplate sclerosis may play a role in disc degeneration.

Morphological features of the epididymal epithelium of gerbil, Meriones unguiculatus.

Principal cells of the ducts epididymis of the Mongolian gerbil showed ultrastructural characteristics of lining epithelium cells close related to processes of protein secretion, and transcytosis occurring between adjacent principal cells which were mainly verified in the initial segment. Principal cells also presented roles of fluid phase and adsorptive endocytoses, as well as autophagic and heterophagic lysosomal activities mainly observed in the caput epididymis. Columnar (principal) cells of the corpus epididymidis presented great number of variable vesicles and vacuoles distributed in all the cytoplasmic levels occurring a progressive coalescence pattern among them, which help to guarantee formation of cytoplasmic channels for fluid phase transport between the tubular lumen and epididymal interstitium. Clear cells were presented in the initial segment and predominately in the cauda epididymis epithelium of the gerbil and showed marked ultrastructural characteristics of endocytosis activities occurrence, perhaps directly related to the turnover of fluid phase of spermatozoa stored into the lumen of the distal tail. Other epididymal epithelium cells were verified and described such as basal, halo, apical and dark cells, but they did not presented special ultrastructural features.

Novel structures in marginal and intermediate cells presumably relate to functions of apical versus basal strial strata.

Prior ultrastructural studies showed that K+ supplied to the stria vascularis came from recycling ions from the organ of Corti or perilymph to strial basal cells. A newly distinguished basal subtype of intermediate cell (BIC) completely covered the basal cells with a leaf-like horizontal process and appeared situated to absorb from them all of the recycled K+. The basal region of marginal cells (MCs) projected foot-like and enlarged processes to border BICs opposite an unique ca. 150 angstroms space. These basal MC processes appeared positioned to resorb part of the K+ recycled to BICs. A second, upper subtype of IC (UIC), occupying middle to upper strial strata, contacted BIC's extensively. UICs were thus located to resorb from BICs the portion of the recycled K+ not forwarded to basal MC processes. The apical segment of MCs projected mitochondria-filled primary processes and numerous associated secondary processes. The Na,K-ATPase-rich secondary processes populated mid to upper stria where they could siphon K+ from UICs and resorb and secrete the ions thus generating the 150 mM [KCl] of endolymph. The morphologic relationship of basal marginal cell processes to BICs differed so strikingly from the relation of upper MC processes to UICs as to suggest a different function for basal stria, one possibly concerned with generating the endocochlear potential.

Projections of the posterodorsal preoptic nucleus and the lateral part of the posterodorsal medial amygdala in male gerbils, with emphasis on cells activated with ejaculation.

The posterodorsal preoptic nucleus (PdPN) and the lateral part of the posterodorsal medial amygdala (MeApd) express Fos with ejaculation in male gerbils. Ejaculation-activated cells participate in the PdPN and MeApd projections to each other and to the sexually dimorphic preoptic area (SDA), but those projections involve less than 20% of the activated PdPN cells and less than 50% of the activated MeApd cells. To identify other potential targets of ejaculation-activated cells, we traced PdPN and lateral MeApd outputs using biotinylated dextran amine. The principal part of the bed nucleus of the stria terminalis (BSTpr) and the anteroventral periventricular nucleus (AVPv) were labeled from both sites and were injected with Fluoro-Gold to determine whether PdPN and lateral MeApd cells that express Fos with ejaculation would be retrogradely labeled. Fluoro-Gold was also applied to the dorsomedial hypothalamus (DMH) and retrorubral field (RRF) because such injections label PdPN cells in rats. The PdPN-DMH projection is minimal in gerbils, involving few, if any, ejaculation-related cells. Ejaculation-activated PdPN cells project to the AVPv (43%), dorsal BSTpr (30%), and RRF (12%). Those in the lateral MeApd project to the dorsal BSTpr (43%) and AVPv (18%). When these percentages are combined with those for ejaculation-activated cells involved in the PdPN and lateral MeApd projections to each other and to the medial SDA, the totals reach 100%. Thus, every PdPN and MeApd cell activated with ejaculation may participate in one of these projections. Similar projections may contribute to the similar behavioral effects of the PdPN and MeApd.

Anatomical and functional connections among cell groups in the gerbil brain that are activated with ejaculation.

Based on Fos expression, four areas of the gerbil brain are activated with ejaculation, i.e., the posterodorsal preoptic nucleus (PdPN), the lateral part of the posterodorsal medial amygdala (MeApd), the medial cell group of the sexually dimorphic preoptic area (medial SDA), and the parvicellular part of the subparafascicular thalamus (SPFp). The SPFp and medial SDA also express Fos earlier in the context of mating. To study connections among these areas, we injected one with FluoroGold and assessed the colocalization of FluoroGold and mating-induced Fos in the others. To determine if any of these areas activates the others, we lesioned one unilaterally and measured mating-induced Fos ipsilaterally and contralaterally in the others. Half of the SPFp cells projecting to the medial SDA, PdPN, and MeApd were activated with mating. SPFp lesions also decreased Fos expression in those areas. However, those areas do not project to the SPFp or affect its Fos expression with mating. Projections from the lateral MeApd to the medial SDA and PdPN, and from the medial SDA to the lateral MeApd, were also activated with mating, but lesions in these areas did not affect Fos expression in the others. Because 32-50% of the mating-activated cells in the SPFp participated in each SPFp projection identified, projections may have been identified for all of the mating-activated cells in the SPFp. In contrast, most of the mating-activated cells in the lateral MeApd, PdPN, and medial SDA do not participate in any projection studied, suggesting that they are either interneurons or project elsewhere.

Morphology of the submandibular gland of the gerbil meriones unguiculatus: a macroscopic and light microscopy study

La morfología de la glándula submandibulardel gerbil fue estudiada macro y microscópicamente. Diez gerbiles fueron anestesiados, perfundidos e inyectados con formalina al 10 por ciento. La región cervical anterior de cada animal fue disecada para efectuar el análisis macroscópico de la glándula submandibular. Para el análisis histológico, las piezas fueron fijadas en la misma solución e incluidas en parafina para los procesos de rutina. Cortes seriados de 6-um fueron teñidos con hematoxilina-eosina y picrosirius, para análisis al microscopio de luz. Los resultados mostraron que la glándula submandibular de gerbil presentaba una forma ovoidea y localizada en la región submandibular, midiendo aproximadamente 9.0 mm de longitud y 5.9 mm de ancho. Histológicamente, cada acino estaba constituido por cuatro tipos de células dispuesta irregularmente. El sistema de ductos constaba de cuatro segmentos distintos: ductos intercalar, granuloso, estriado y excretor

The Harderian gland of the Cheesman's gerbil (Gerbillus cheesmani ) of the Kuwaiti desert.

The Harderian gland is a large orbital structure. Several functions have been ascribed to the gland such as lubrication of the eye, a source of pheromones, thermoregulartory lipids and photoprotective secretions and a part of the retinal-pineal axis. In the present study, the Harderian gland of the Cheesman's gerbil, Gerbillus cheesmani, is described for the first time. The gland is located around the posterior portion of the eyeball. The gland is compound tubular, surrounded by a thin connective tissue capsule. Only one secretory epithelial cell type was recognized, characterized by the presence of lipid vacuoles and cytoplasmic slashes in high numbers; the former being more concentrated towards the apical part while the latter being more concentrated towards the central and basal parts. Some of the cytoplasmic slashes contained electron dense filamentous structures. Similar structures were observed in the lipid vacuoles. Thus, a functional relationship between the cytoplasmic slashes and the lipid vacuoles is suggested. A unique structure was observed, termed dome-like cells, located between the epithelial cells and the basement membrane. These cells were characterized by the extensive presence of pleomorphic mitochondria and compact lamellae of granular endoplasmic reticulum (GER) in the form of finger prints. The gland was found to be actively secreting porphyrins as well as lipids. Cellular debris was also seen in the tubular lumina. Myoepithelial cells with their spindle shape and elongated nuclei were evident between the basement membrane and the secretory epithelium. Sparse interstitial tissue was observed in-between the gland tubules of both male and female gerbils. Macrophages, dendritic melanocytes and lymphocytes are the most represented cellular components of the interstitium. Further studies are required to investigate the function of the dome-like cells as well as the role of lymphocytes in the rodents Harderian gland.

Morphologic study of the masseter muscle of gerbil: meriones unguiculatus

El daño de los músculos masticadores relacionados con desórdenes cráneomandibulares son aspectos comunes en la clínica. Es importante contar con datos morfológicos de estos músculos en el sistema estomatognático. El propósito de este trábajo es mostrar la morfología del músculo masetero del gerbil Meriones unguiculatus, desde el nivel macroscópico hasta el de microscopía electrónica. En la observación macroscópica fueron utilizados 5 animales que fueron perfundidos con sulución de formalina al 100 por ciento. Las disecciones fueron fotografiadas. Posteriormente, los músculos fueron removidos e sumergidos en la solución de formalina, por unos pocos días. Las muestras fueron procesadas a través de técnicas histológicas convencionales y sumergidas en parafina. Cortes seriados de 6 um fueron teñidos con H. E. analizados y fotografiados con un fotomicroscopio JENAMED. Nuestros resultados mostraron que el músculo masetero presentaba 5 fascículos, los cuales se mezclaban en la porción media, y algunos husos estaban fusionados con la cápsula externa de ellos mismos, pareciendo husos gigantes

Fine structure of the lining epithelium of the ductus deferens in gerbil: a segmental study

The cell types observed in the epithelium that lines the ductus deferens of the gerbil were principal, basal, narrow, and apical (mitochondria-rich) cells, whose cellular ultrastructure and segmental features were described. The morphological characteristics of the lining epithelium of the ductus in the three main tubular segments: adepididymic (proximal), funicular (middle) and adprostatic (distal) were presented. The cytophysiological role of the epithelial cell types in each segment was discussed on a comparative base. Resorption of seminiferous fluid and adsorptive endocytosis seem to be the main functions of the principal and apical cells. Moreover, secretory functions may occur in both cell types, mainly in principal cells in which ultrastructural characteristics of the Golgi-ER complex had been related to cellular secretion, perhaps of protein. Another ultrastructural feature of the supranuclear cytoplasm of principal cells was the presence of apical cytoplasmic expansions (apical protrusions), observed mainly in the epithelium of the distal ductus deferens segment, with suggestion of apocrine secretory process occurrence.

Ultrastructural study of the conjunctival epithelium in the Mongolian gerbil (Meriones unguiculatus).

The conjunctival epithelium of the Mongolian gerbil (Meriones unguiculatus) was studied using the transmission and scanning electron microscopy. The superficial cells of the conjunctival epithelium were isoprismatic in shape and were covered, on their luminal surface, with microplicae. They were connected with the adjacent cells by junctional complexes and desmosomes. Some of the superficial cells were partially or completely detached from the underlying intermediate cells: this morphological pattern was interpreted as an expression of cellular renewal of the conjunctival surface. Goblet cells were either isolated or gathered in clusters: in any case, they were firmly connected with the adjacent epithelial cells. The apical part of the goblet cells was covered with a great number of long microvilli: they showed a variety of morphological aspects, which were interpreted as occurring in a sequential pattern during the secretory process. The Mongolian gerbil can be considered among the laboratory animals used for ophthalmic research.

Caracteristicas histologicas del meriones unguiculatus utilizado en experimentos / Histologic characteristics of Meriones unguiculatus used in experimental trials

Para determinar las caracterisiticas histologicas de Meriones unguiculatus sanos sometidos a las condiciones de animal de experimentacion, se realizo el estudio de los organos fundamentales de 50 especimenes sanos machos (encefalo, corazon, pulmones, higado, rinones, tractus gastrointestinal, bazo y testiculos). Se procesaron los organos en formol neutro al 10 por ciento. Se colorearon con hematoxilina-eosina y la coloracion especial de Von Kossa para demostrar la presencia de calcio. Se encontro principalmente congestion visceral de diferentes grados en un 100 por ciento y un deposito de material homogeneoen los tubulos de composicion calcica, en el 16 por ciento. este ultimo hallazgopuede ser de interes en estudios de insuficiencia renal cronica