Identification of the proliferative activity of germline progenitor cells in the adult ovary of the bat Artibeus jamaicensis.

Until a few years ago, it was assumed that oocyte renewal did not take place in the ovary of adult organisms; however, the existence of germline progenitor cells (GPCs), which renew the ovarian follicular reserve, has now been documented in mammals. Specifically, in the adult ovary of bats, the presence of cells located in the cortical region with characteristics similar to GPCs, called adult cortical germ cells (ACGC), has been observed. One of the requirements that a GPC must fulfil is to be able to proliferate mitotically, so the evaluation of cell proliferation in ACGC is of utmost importance in order to be able to relate them to a parental lineage. Currently, there are several methods to determine cell proliferation, including BrdU labelling or the use of endogenous proliferation markers. Thus, the aim of this work was to evaluate the proliferative activity of ACGC in the adult ovary of the bat Artibeus jamaicensis, using different proliferation markers and correlating these with the protein expression of the transcription factor Oct4 and the germ line marker Ddx4. We found that the expression pattern of the proliferation markers BrdU, PCNA, Ki-67 and pH3 occurs at different times of the cell cycle, so co-localization of two or more of these markers allows us to identify proliferating cells. This allowed us to identify ACGC with proliferative capacity in the adult ovary of A. jamaicensis, suggesting that GPCs renew the follicle reserve during the adult life of the organism.