Diego Carvalho Viana

Characterization of the estrous cycle in Galea spixii(Wagler, 1831)

The Galea spixii inhabits semiarid vegetation of Caatinga in the Brazilian Northeast. They are bred in captivity for the development of researches on the biology of reproduction. Therefore, the aim of this study is characterize the estrous cycle of G. spixii, in order to provide information to a better knowledge of captive breeding of the species. The estrous cycle was monitored by vaginal exfoliative cytology in 12 adult females. After the detection of two complete cycles in each animal, the same were euthanized. Then, histological study of the vaginal epithelium, with three females in each phase of the estrous cycle was performed; five were paired with males for performing the control group for estrous cycle phases, and three other were used to monitor the formation and rupture of vaginal closure membrane. By vaginal exfoliative cytology, predominance of superficial cells in estrus, large intermediate cells in proestrus, intermediate and parabasal cells, with neutrophils, in diestrus and metestrus respectively was found. Estrus was detected by the presence of spermatozoa in the control group. By histology, greater proliferation of the vaginal epithelium in proestrus was observed. We conclude that the estrous cycle of G. spixii lasts 15.8 ± 1.4 days and that the vaginal closure membrane develops until complete occlusion of the vaginal ostium, breaking after few days. Future studies may reveal the importance of this fact for the reproductive success of this animal.

Follicular development and morphological changes in the vaginal epithelium during the estrous cycle of Galea spixii.

The current study aimed to determine if characteristics observed in vaginal cytology during the estrous cycle of female SYT cavies corresponded with proliferation of the vaginal epithelium, characterized by proliferating cell nuclear antigen (PCNA) immunolocalization, and with follicular development at different phases of the estrous cycle. After determining estrous cycle phases by vaginal cytology, females were euthanized at metestrus, diestrus, proestrus, and estrus. Histological study of the vaginal epithelium and ovary were then performed. Immunohistochemistry for PCNA in vaginal tissue at each cycle phase was also performed. Superficial cornified cells and early post‐ovulatory follicles were found at estrus. Few nuclei below the enucleate superficial cells were immunoreactive to PCNA. At metestrus, the vaginal epithelium underwent desquamation and lost the superficial cornified cells; basal and intermediate cells appeared, and the post‐ovulatory follicle formed an early corpus luteum. No PCNA immunoreactivity was observed. At diestrus, the corpus luteum was developed, and the vaginal epithelium contained basal and intermediate cells. There was PCNA immunoreactivity in the cellular nucleus in the germinative stratum of the epithelium. Because of the growth and maturation of ovarian follicles, the vaginal epithelium suffered intense proliferation at proestrus. Vaginal cytology revealed large intermediate cells and nucleated and enucleated superficial cornified cells. In the ovary, mature follicles were present. More apparent immunoreactivity of PCNA in the germinative layer was found. In summary, we inferred that vaginal exfoliative findings matched the proliferation process of the vaginal epithelium. PCNA immunolocalization occurred as well as corresponding follicular development in the ovaries.

Seasonal morphological variation of the vas deferens of scorpion mud turtle (Kinosternon scorpioides)

This study aimed to characterize the morphology of the vas deferens of Kinosteron scorpioides by macroscopic and microscopic analysis. Were used 20 adult male juraras collected at regular intervals during the year and divided into four experimental groups in the rainy and dry seasons, being processed for light microscopy, scanning electron microscopy and transmission electron microscopy. Morphometry for tubular and luminal diameters and epithelial height were also performed. On rainy season, vas deferens presented pseudostratified epithelium with cylindrical cells, spermatozoids and milky fluid in the lumen, with cytoplasmic organelles and lipid vesicles. On dry season, epithelium was pseudostratified with cuboid cells, with cellular debris and no spermatozoids. There was significant variation (p,0,05) for morphometry of vas deferens, with lower values of tubular and luminal diameters on rainy season, and higher epithelial height on dry season.

Análise microscópica e ultraestrutural das glândulas salivares mandibulares de Procyon cancrivorus

Due to the ecological importance of Procyon cancrivorus, the aim of this study was to characterize morphologically and ultrastructurally the mandibular salivary gland of this specie. We used 10 pairs (right and left) of mandibular salivary glands from five adult animals. The mandibular salivary glands were dissected and measured by precision calipers and later processed by histological routine technique, stained by HE (hematoxylin and eosin) and Picrossirius. Fragments of the glands were processed for analysis by scanning electron microscopy (SEM). The mandibular salivary gland, right and left from P. cancrivorus presents lobulated and oval-shape, and it was positioned between the fossa atlantis and basihyoideum ossis of skull. Microscopically, these glands are lined by a capsule formed by dense irregular connective tissue, which enters into the gland by septa, dividing it into lobules. Into the septa of connective tissue were present blood vessels and nerves, and interlobular excretory ducts. Inside the lobes of the mandibular salivary glands, striatum and intermediate-type ducts are found, and the predominance of mucous acini was observed. The results indicate that the mandibular salivary glands of Procyon cancrivorus, follows the structural pattern described in other mammalian species. However the types of acini may vary among species, and thus further histochemical and cell biology studies are required in order to uncover the significance of this variation for the specie here studied, according with their feeding habit.

Development of the central nervous system in guinea pig (Cavia porcellus, Rodentia, Caviidae)

This study describes the development of the central nervous system in guinea pigs from 12th day post conception (dpc) until birth. Totally, 41 embryos and fetuses were analyzed macroscopically and by means of light and electron microscopy. The neural tube closure was observed at day 14 and the development of the spinal cord and differentiation of the primitive central nervous system vesicles was on 20th dpc. Histologically, undifferentiated brain tissue was observed as a mass of mesenchymal tissue between 18th and 20th dpc, and at 25th dpc the tissue within the medullary canal had higher density. On day 30 the brain tissue was differentiated on day 30 and the spinal cord filling throughout the spinal canal, period from which it was possible to observe cerebral and cerebellar stratums. At day 45 intumescences were visualized and cerebral hemispheres were divided, with a clear division between white and gray matter in brain and cerebellum. Median sulcus of the dorsal spinal cord and the cauda equina were only evident on day 50. There were no significant structural differences in fetuses of 50 and 60 dpc, and animals at term were all lissencephalic. In conclusion, morphological studies of the nervous system in guinea pig can provide important information for clinical studies in humans, due to its high degree of neurological maturity in relation to its short gestation period, what can provide a good tool for neurological studies.

Development and Morphological Changes in the Vaginal Closure Membrane Throughout Gestation in Galea spixii (Rodentia: Caviidae)

Present research was carried out in order to perform the monitoring of development, recognizes the type of tissue and describes histological and cellular changes of the vaginal closure membrane (VCM) throughout pregnancy in Galea spixii. The results showed that at 20 days of gestation (DG), the VCM occludes completely the external vaginal ostium. Microscopically, the VCM presented juxtaposed cells, derived from the stratum germinative of the stratified epithelium of vaginal mucosa at 20 DG and areas with cell clusters with the presence of intercellular spaces in the final stages of pregnancy (40‐50 DG). At 0 DG, the stratified epithelium of vaginal mucosa presented all strata but at 20 DG presented stratified epithelium without the stratum corneum and stratum granular and showed communicant junctions by desmosomes and interdigitations in the cell membrane compound the VCM. Gradually from 40 to 50 DG the stratum germinative became barely perceptible. Many cells showed apoptotic nuclei and emerged many intercellular spacing. So, the interdigitations and desmosomes were not observed. Here, it was demonstrated for the first time that the VCM is formed after the extinction of the stratum granular and corneum of the vaginal mucosa epithelium, with the proliferation of the cells of stratum germinative and communication and junction through desmosomes and interdigitations of these cells. At the end of pregnancy, cellular apoptosis; the spread of stratum germinative; and, absence of cellular communication and junction may be responsible for the weakening of the VCM and may assist the process of rupture of this membrane. Microsc. Res. Tech. 79:359–364, 2016.

Immunolocalization of steroidogenic enzymes in the vaginal mucous of Galea spixii during the estrous cycle

BackgroundThe synthesis of sex steroids is controlled by several enzymes such as17α-hydroxylase cytochrome P450 (P450c17) catalyzing androgen synthesis and aromatase cytochrome P450 (P450arom) catalyzing estrogen synthesis, both of which must complex with the redox partner NADPH-cytochrome P450 oxidoreductase (CPR) for activity. Previous studies have identified expression of steroidogenic enzymes in vaginal tissue, suggesting local sex steroid synthesis. The current studies investigate P450c17, P450aromatase and CPR expression in vaginal mucosa of Galea spixii (Spix cavy) by immuno-histochemical and western immunoblot analyses.MethodsStages of estrous cyclicity were monitored by vaginal exfoliative cytology. After euthanasia, vaginal tissues were retrieved, fixed and frozen at diestrus, proestrus, estrus and metestrus. The ovaries and testis were used as positive control tissues for immunohistochemistry.ResultsData from cytological study allowed identification of different estrous cycle phases. Immunohistochemical analysis showed different sites of expression of steroidogenic enzymes along with tissue response throughout different phases of the estrous cycle. However, further studies are needed to characterize the derived hormones synthesized by, and the enzymes activities associated with, vaginal tissues.ConclusionCurrent results not only support the expression of enzymes involved in sex steroid synthesis in the wall of the vagina, they also indicate that expression changes with the stage of the cycle, both the levels and types of cells exhibiting expression. Thus, changes in proliferation of vaginal epithelial cells and the differentiation of the mucosa may be influenced by local steroid synthesis as well as circulating androgens and estrogens.

Intrauterine sexual differentiation: biosyntesis and action of sexual steroid hormones

The objective of this review was to describe sexual differentiation events in mammals, relating them to biosynthesis of sexual steroid hormones and their mechanisms of action. Cholesterol is the precursor of sexual steroid hormone biosynthesis via action of several enzymes converting these hormones. Progestagens hormones serve as substrate for the production of androgens, which in turn serve as substrate for estrogen hormones. These hormones are responsible for sexual differentiation and reproductive cycles of mammals. Sexual differentiation process comprises determining the sexual chromosomes XX or XY + SRY and other genes linked to them, differentiation of gonads in testis or ovary, differentiation of internal and external male or female genital organs from undifferentiated anatomical structures present in the embryo, which is dependent on the presence or absence of testes and the production of anti-Mullerian hormone and testosterone; and secondary sexual differentiation, which is the response of various tissues to hormones produced by the gonads, interacting with genes linked to sexual chromosomes to increase or decrease the differences in sexual phenotype. However, some differences between the sexes and some anomalies of sexual differentiation are not explained only by these sexual hormonal effects, but also by the effect of genes encoded in sexual chromosomes.

Nematoda of Kinosternon scorpioides (Testudines: Kinosternidae) from Northeastern Brazil

Abstract The scorpion mud turtle (Kinosternon scorpioides) is a small freshwater turtle broadly distributed in South America and commonly consumed in some Brazilian regions. This study aimed to identify the species of helminths that parasitize the digestive tract of K. scorpioides and report infection parameters such as parasite prevalence, mean intensity of the infection, abundance, and the relationship between these nematodes and host body size in this species. We captured 20 adult male K. scorpioides, and 6 animals had nematodes in their gastrointestinal tract. These animals had Serpinema magathi (prevalence = 0.3) and Spiroxys figueiredoi (prevalence = 0.25). There were no correlations between the number of total parasites and carapace length (rs = 0.17, n = 6, P = 0.74) or the length of the gastrointestinal tract (rs = 0.18, n = 6, P = 0.73).

Adrenal glands of Spix's yellow-toothed cavy (Galea spixii, Wagler, 1831): morphological and morphometric aspects

Considering the physiological importance and need of greater morphophysiological knowledge of adrenal glands, the aims of present study were compare the morphometric data between left and right adrenal of male and female; perform a histological, scanning and transmission electron microscopy study showing tissue constitution of glands; finally, in order to define the presence and correct site of the cytochrome P450c17 expression in adrenal glands, immunohistochemical study of this enzyme was performed in 18 adrenal glands (right n=9 and left n=9) of nine adult Galea spixii (four males and five females). Right adrenal was more cranially positioned than left adrenal; dimensions (weight, length and width) of right adrenal was larger than left adrenal; no differences between male and female body and adrenal measurements were found; the morphology of cells and different amounts of lipid droplets may be related to the different demands of steroid hormones production, related to each zone of the adrenal cortex; and, the cytochrome P450c17 immunolocalization in fasciculate and reticular zone may be related with synthesis of 17-hydroxy-pregnenolone, 17-hydroxy-progesterone, dehydroepiandrosterone or androstenedione.