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

Abstract

The study investigated the gross and microscopic anatomy of the genital organs of 20 agoutis at different stages of the estrous cycle and four in the final trimester of pregnancy. Specimens were euthanized and their reproductive organs were fixed in a 4% paraformaldehyde or 2.5% glutaraldehyde solution and submitted to routine histological techniques for light and scanning electron microscopy. In the ovary, during the proestrus phase, we observed developing follicles and corpus luteum (CL) in regression; during estrus, there were Graafian follicles; during metestrus, there was a hemorrhagic corpus, whereas in diestrus, there was a mature CL. The uterus was partially double because the cervix was cranially septate but caudally, the septum disappeared, forming a single ostium that opened into the vagina. Changes occurred along the estrous cycle in the uterine and vaginal epithelia, that is, an increase in the uterine epithelium height accompanied by an increase of thickness of the vaginal epithelium during the follicular phase and a decrease of thickness of both epithelia during the luteal phase. The endometrial lining was composed of a simple cuboidal epithelium to simple columnar epithelium with basal nuclei. The vaginal mucosa consisted of epithelium that varied from nonkeratinized stratified squamous (luteal phase) to keratinized stratified squamous (follicular phase). The clitoris was external to the vagina. It presented two protruding lateral keratinized spicules and a centralized urethra, with no common parts between the urinary and genital tracts. Anatomical and histological changes were observed mainly in the cervix, vagina and spicules of the clitoris during the EC.

Reproductive Technologies Used in Female Neo-Tropical Hystricomorphic Rodents

“…Mayor et al [ 25 ] found that the length of the uterine tubes of D. fuliginosa was 0.504 ± 0.123 cm and, also, that the length did not differ with the reproductive state. This was in stark contrast to de Oliveira et al [ 42 ], who found that the length of the uterine tubes for the D. leporina was 5.023 ± 2.51 cm and 4.911 ± 2.05 cm for the left and right uterine tubes, respectively. They also reported that the left and right uterine horns were 5.052 ± 0.423 cm and 5.176 ± 0.419 cm in length, respectively, which then went on to form a false uterine body caudally that varied in diameter between the different estrous cycle phases.…”

“…The ovaries were pale yellow in colour with tiny translucent areas that were oval in shape and had a smooth surface with no ovarian bursa [ 14 , 20 , 25 , 40 , 41 , 42 ]. The ovary, found within adipose tissue and supported by the mesovarium, was enclosed by the tunica albuginea and consisted of two layers—the cortex, which was the outer layer, and the medulla, which was the inner layer [ 40 , 41 , 42 ].…”

“…The ovaries were pale yellow in colour with tiny translucent areas that were oval in shape and had a smooth surface with no ovarian bursa [ 14 , 20 , 25 , 40 , 41 , 42 ]. The ovary, found within adipose tissue and supported by the mesovarium, was enclosed by the tunica albuginea and consisted of two layers—the cortex, which was the outer layer, and the medulla, which was the inner layer [ 40 , 41 , 42 ]. Weir [ 20 ] stated that the ovaries weighed 0.207 ± 0.019 g, however, Oliveira et al [ 42 ] found that both the right and left ovaries had the same weight of 0.09 ± 0.01 g. Further morphometric data of the ovary could be seen in Table 1 .…”

“…There were three parts of the uterine tubes: the infundibulum, ampulla, and isthmus [ 25 , 42 , 43 ]. The paired uterine horns increased in width as they approached the uterus and had a mean length of 2.2 ± 0.19 cm, with the left uterine horn being more tortuous [ 41 ].…”

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“…Namely, anatomy of the male and female 3 reproductive system have increased the limited body of knowledge on the species. Furthermore, the estrous cycle, 22,23 related hormonal activity 24,25 and stimulatory effect of the presence of the male agouti on the onset of female puberty 17 will assist in the application of assisted reproductive techniques (ART) in the species. Technicians would be guided by the anatomy of the female's reproductive tract for the intrusion of probes and other invasive instruments to deposit semen samples at the precise point of fertilization.…”