Key characteristics of the ovary and uterus for reproduction with particular reference to poly ovulation in the plains viscacha (Lagostomus maximus, chinchillidae)

• Published in: Theriogenology Vol. 142; pp. 184 - 195
• Main Authors: Flamini, Mirta Alicia, Barreto, Rodrigo S.N., Matias, Gustavo S.S., Birbrair, Alexander, Harumi de Castro Sasahara, Tais, Barbeito, Claudio Gustavo, Miglino, Maria Angelica
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 15.01.2020
• Subjects: Animal model; Embryo to uterus interaction; Functional anatomy; Germinative cells; Primary follicles; Primary follicles; Animal model; Functional anatomy; Embryo to uterus interaction; Germinative cells
• ISSN: 0093-691X; 1879-3231
• DOI: 10.1016/j.theriogenology.2019.09.043

One of the dogmas of mammalian reproduction states is that primordial germ cells in females are restricted to the intrauterine phase, and that only a small portion of oocytes is available for ovulation during the adult life. Among the rare exceptions to this rule is the plains viscacha. This specie polyovulates up to 800 oocytes per cycle, from which 10 to 12 are implanted, but only 1–2 conceptuses survive. To better understand the key mechanisms of this pattern of embryonic to uterine interactions, we analyzed 19 female genital systems by means of gross morphology, histology, stereology and immunohistochemistry. Data showed that a specialized, highly convoluted structure of the ovarian cortex developed during the intrauterine phase as a prerequisite for the massive super-ovulation, likely associated with the inhibition of apoptosis and continued proliferation of germ cells, as well as maintenance of several corpora lutea during the adult life. In addition, specializations of uterine vasculature and musculature were demonstrated. Altogether, these key morphological characteristics evolved in order to contribute as compensatory or controlling mechanism for polyovulation and polyimplantation that led these species into becoming an unique enigma in reproductive biology, and a potential animal model to provide explanations regarding to developmental specializations. •Specializations of uterine vasculature and musculature in viscacha.•Key morphological innovations on maternal side support the embryonic development.•Unusual female reproductive biology in viscacha.•Complex pattern of polyovulation, polyimplantation and controlling mechanisms.