massive-ovulation-mammals-techniques-for-analyzing-natural

Massive Ovulation in Mammals: Techniques for Analyzing Natural Spontaneous Polyovulation and Induced Polyovulation in <em>Lagostomus maximus</em>

The South American plains vizcacha, Lagostomus maximus, is recognized as the mammalian species with the highest ovulation rate, which can reach as many as ...

Universidad Maimónides

Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)

The corpus luteum (CL) is a transient endocrine gland that plays a crucial role in establishing and maintaining pregnancy. Although autophagy and apoptosis have been suggested as cooperative mechanisms, their interaction within the CL of pregnant mammals has not been thoroughly investigated. To understand the collaborative function of autophagy and apoptosis in the CL, we analyzed both mechanisms during pregnancy in the South American plains vizcacha, Lagostomus maximus. This rodent undergoes a decline in progesterone levels during mid-gestation, a reactivation of the hypothalamus-hypophysis-gonadal axis, and the incorporation of new functional secondary CL. Our analysis of autophagy markers BECLIN 1 (BECN1), SEQUESTOSOME1 (SQSTM1), Microtubule-associated protein light chain 3 (LC3B), and lysosomal-associated membrane protein 1 (LAMP1) and anti- and pro-apoptotic markers BCL2 and ACTIVE CASPASE 3 (A-C3) revealed interactive behaviors between both processes. Healthy primary and secondary CL exhibited positive expression of BECN1, SQSTM1, LC3B, and LAMP1, while regressed CL displayed enhanced expression of these autophagy markers along with nuclear A-C3. Transmission electron microscopy revealed a significant formation of autophagic vesicles in regressed CL during full-term pregnancy, whereas healthy CL exhibited a low number of autophagy vesicles. The co-localization between LC3B and SQSTM1 and LC3B with LAMP1 was observed in both healthy and regressed CL during pregnancy, while co-localization of BECN1 and BCL2 was only detected in healthy CL. LC3B and ACTIVE CASPASE 3 co-localization were detected in a subset of luteal cells within the regressing CL. We propose that autophagy could act as a survival mechanism in the CL, allowing the pregnancy to progress until full-term, while also serving as a mechanism to eliminate remnants of regressed CL, thereby providing the necessary space for subsequent follicular maturation.

Autophagy favors survival of corpora lutea during the long-lasting pregnancy of the South American plains vizcacha, Lagostomus maximus (Rodentia, Caviomorpha).

The South American plains vizcacha, Lagostomus maximus, is recognized as the mammalian species with the highest ovulation rate which can reach as many as 800 ova. This remarkable polyovulation phenomenon was first reported in the 1970s and has remained unchanged in its findings ever since. We conducted an extensive re-evaluation of ovulation in L. maximus by examining natural ovulation, ovulation induced through the administration of exogenous hormones and autologous seminal plasma, while also categorizing the morphological characteristics and maturation stages of the released ova. Our results confirm L. maximus as the foremost polyovulatory mammalian species, albeit with a mean of 154 ± 87, ranging from 29 to 326 oocytes per oestrous cycle. We observed the concurrent presence of spontaneous ovulation, serving as a mechanism to eliminate defective oocytes, alongside induced ovulation, referred to as "euovulation," that promotes the release of cumulus-oocyte complexes suitable for fertilization. In addition, we provide evidence for the involvement of seminal plasma in the process of induced ovulation and show that the "pseudovulation" phenomenon occurring at mid-gestation, which contributes to the formation of secondary corpora lutea, does not entail the release of oocytes into the oviducts. Our analysis also revealed the presence of spontaneous parthenogenetic oocyte activation and subsequent development, which occurred both during oocyte release in the ovulatory phase and within unruptured follicles in the ovary.

Article	Year
Autophagy favors survival of corpora lutea during the long-lasting pregnancy of the South American plains vizcacha, Lagostomus maximus (Rodentia, Caviomorpha). Scientific reports\| PubMed ID: 38755206	2024
Polyovulation in the South American Plains Vizcacha, Revisited: Coexistence of Spontaneous and Induced Ovulation. Journal of experimental zoology. Part A, Ecological and integrative physiology\| PubMed ID: 40165530	2025

Daira A. Caram

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