Development and morphological changes in the vaginal closure membrane throughout gestation inGalea spixii(Rodentia: Caviidae)

Abstract

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.

Morphology of the genital organs of the female red‐rumped agouti (Dasyprocta leporina, Linnaeus, 1758) during estrous cycle phases and in advanced pregnancy

“…Further studies are needed to elucidate the factors involved in the formation process of the mucus plug and vaginal closure membrane. Until now, Santos, Oliveira, et al () demonstrated that the vaginal closure membrane has a cellular formation and breakage control in pregnant G. spixii ; its formation is associated with the proliferation of cells in the germinative layer of the epithelium, with the formation of desmosome junctions between these cells and their rupture being associated with apoptosis and loss of cell adhesion. Notably, the formation of this mucus plug and the consequent formation of this closure membrane is a typical characteristic of rodents, and it could be associated with preventing the action of males after copulation (Adrian & Sachser, ).…”

“…The reproductive system of these animals consists of ovaries, uterine tubes, a partially double uterus, cervix, and vagina (Martins et al, ; Mayor, Bodmer, & Bejar, ; Singh, Adogwa, Mollineau, & Garcia, ). Similar to other rodent species (e.g., Cavia porcellus (Stockard & Papanicolaou, ), Thryonomys swinderianus (Addo et al, ), Octodon degus (Mahoney, Rossi, Hagenauer, & Lee, ), and Galea spixii (Santos et al, , )), a vaginal closure membrane forms in agoutis at certain stages of the estrous cycle (Weir, ).…”

Development of Adrenal Glands from the Embryonic Phase to Puberty in Spix’s Yellow-toothed Cavies (Galea spixii, Wagler, 1831)

“…Current analysis detailed the morphological development of the adrenal glands of SYT cavies from the embryo phase to puberty. Data are important since SYT cavies have been used as experimental models for embryonic studies [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] , studies on reproduction physiology [5][6][7][8][9][10][11][12][13][14][15][16] and on the morphology and adrenal steroidogenesis in adult animals [4] . Current analysis revealed topographic asymmetry between the adrenal glands, or rather, the right gland lying cranially towards the left.…”

Follicular development and morphological changes in the vaginal epithelium during the estrous cycle ofGalea spixii

“…Therefore, the species is bred in captivity for sustenance. Moreover, due peculiar morphological and reproductive characteristics found in previous studies, SYT cavies serve as an experimental model for research on reproductive biology (Oliveira et al, ; Santos et al, ).…”

“…Female Spix's yellow‐toothed cavies have a continuous poliestral cycle (Oliveira et al, ) that lasts 14–19 days in captive females. A vaginal closure membrane develops during the estrous cycle (Santos et al, ) and pregnancy (Santos et al, ), and different steroidogenic enzymes are present in the vaginal epithelium at different cycle phases corresponding with epithelial proliferation (Santos et al, ). With regard to cellular proliferation on the vaginal epithelium, one study (Deanesly, ) described the vaginal epithelium of Cavia porcellus is variously stimulated by different hormones resulting from ovarian follicular development throughout the estrous cycle.…”