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

Placental development in the early stages of red-rumped agouti pregnancy (Dasyprocta leporina Linnaeus, 1758)

BACKGROUND

Hystricomorpha rodents display a similar placentation model to humans. The present study was carried out considering the scarcity of information concerning the placental development in agouti.

OBJECTIVE

Describe the microscopy of the placenta, subplacenta and yolk sac of agoutis in early pregnancy and report on the inversion of the yolk sac.

METHODS

Fifteen females between the 14th-32nd day of gestation were used following euthanasia. Gestational buttons were collected, fixed, processed, stained to optical microscopy or immunohistochemistry.

RESULTS

Chorioallantoic placenta (CP) ranged from conical to a half-sphere, as follows: from the 14th to 17th day, the CP displays an inverted "V" shape, predominantly formed by cytotrophoblasts; from 20 to 22 days, formed almost entirely by cytotrophoblasts; at 28 days, a half sphere, with distinct lobes and interlobular area, numerous maternal gaps delimited by syncytiotrophoblasts and trophoblast giant cells; at 32 days, globose and undergoing the maturation process. Subplacenta, located between decidua and CP, initially presents septa consisting of simple columnar epithelium and after 17 days, comprising stratified epithelium. Visceral yolk sac (VYS) is attached to two CP projections between 14 and 17 days, formed by a simple cubic epithelium and inverted. Between 20 and 22 days, the epithelium displays apical villous projections with cytoplasmic vacuoles and a vascularized mesoderm. After the 24th day, the VYS near the placenta is pleated, very vascularized and villous, with decreased villi sizes further away from the placenta.

CONCLUSION

The agouti CP displays similar characteristics to other hystricomorpha, including placenta lobulation, a subplacenta and an inverted vitelline placenta.

Female Genital Variation Far Exceeds that of Male Genitalia: A Review of Comparative Anatomy of Clitoris and the Female Lower Reproductive Tract in Theria

A review of the literature on the anatomy of the lower female genital tract in therian mammals reveals, contrary to the general perception, a large amount of inter-specific variation. Variation in female external genitalia is anatomically more radical than that in the male genitalia. It includes the absence of whole anatomical units, like the cervix in many Xenarthra, or the absence of the urogenital sinus (UGS), as well as the complete spatial separation of the external clitoral parts from the genital canal (either vagina or UGS). A preliminary phylogenetic analysis shows two patterns. Some morphs are unique to early branching clades, like the absence of the cervix, while others arose multiple times independently, like the flattening out or loss of the UGS, or the extreme elongation of the clitoris. Based on available information, the ancestral eutherian configuration of the external female genitalia included a cervix, a single vaginal segment, a tubular UGS, and an unperforated clitoris close to the entrance of the genital canal. The evidence for either bilobed or unitary glandes clitorides is ambivalent. Despite the wealth of information available, many gaps in knowledge remain and will require a community-wide effort to come to a more robust model of female genital evolutionary patterns.

Reproductive Technologies Used in Female Neo-Tropical Hystricomorphic Rodents

This is the second of two literature reviews that focuses on the female reproductive anatomy and reproductive technologies used in selected neo-tropical hystricomorphic rodents. The rodents chosen included the agouti (Dasyprocta leporina), the capybara (Hydrochoerus hydrochaeris), and the paca (Cuniculus paca). Over seventy references were used, spanning the years 1919–2021. Knowledge of the reproductive tract is important in understanding any unique features, which may affect the use of reproductive technologies. Some unique characteristics common to these species included the presence of a vaginal closure membrane and a lobulated placenta with a vascular sub-placenta. The capybara had hyperpigmentation of the vagina that was unique to each individual, while the agouti and paca had accessory corpora lutea, in addition to the main one. Some reproductive technologies have been used, with attempts at estrous induction and synchronization taking place within the past five years. Even though most work has been done over the past twenty years, there is still a dearth of information.

Anthelmintic usage on the Reproductive Parameters in Captive reared Agoutis (Dasyprocta leporina) in Trinidad and Tobago, West Indies

The agouti (Dasyprocta leporina) is a rodent that is found in the Neo-tropical region. This animal is hunted for its meat but has recently been reared in captivity as a source of meat protein in rural communities. A 20-month experiment was carried out to evaluate the effect of an anthelmintic on the reproductive performance of the agouti (Dasyprocta leporina) reared in captivity. This experiment was conducted in the humid tropics of Trinidad and Tobago. Sixteen animals (15 females, 1 male) placed in each of the two treatment groups in a completely randomized study design. In treatment 1 (T1) animals were given subcutaneous injections of Endovet Ces® (Ivermectin/Praziquantel) at 0.2 mg/kg every three months. Treatment 2 (T2) was the negative control group where animals were not exposed to an anthelmintic. Reproductive data were collected at parturition which included birth weight, litter weight, litter size and gender of offspring. The results showed that there was no statistical difference (p > 0.05) between the treatment groups with respect to birth weight, litter weight, litter size and gender. However, agoutis that were dewormed had a higher birth weight (220.24 g vs 209.1 g) and litter weight (369.8 g vs 343 g). The same values were obtained for the litter size (1.7 vs 1.7) and animals that were dewormed had a higher female offspring to male offspring (2.41:1 vs 1.11:1). This experiment demonstrated that the use of an anthelmintic strategically in the management of captive reared agoutis had no statistical effect (p > 0.05) on the reproductive parameters. Therefore, these animals can be kept in captive conditions without being dewormed and produce efficiently with proper feeding and housing management.