The neonatal southern white rhinoceros ovary contains oogonia in germ cell nests

The northern white rhinoceros is functionally extinct with only two females left. Establishing methods to culture ovarian tissues, follicles, and oocytes to generate eggs will support conservation efforts using in vitro embryo production. To the best of our knowledge, this is the first description of the structure and molecular signature of any rhinoceros, more specifically, we describe the neonatal and adult southern white rhinoceros (Ceratotherium simum simum) ovary; the closest relation of the northern white rhinoceros. Interestingly, all ovaries contain follicles despite advanced age. Analysis of the neonate reveals a population of cells molecularly characterised as mitotically active, pluripotent with germ cell properties. These results indicate that unusually, the neonatal ovary still contains oogonia in germ cell nests at birth, providing an opportunity for fertility preservation. Therefore, utilising ovaries from stillborn and adult rhinoceros can provide cells for advanced assisted reproductive technologies and investigating the neonatal ovaries of other endangered species is crucial for conservation. A comprehensive histological assessment of southern white rhinoceros ovaries from both mature females and a neonate provides insight into follicular development in this species.

Automated summary

The northern white rhinoceros is functionally extinct, with only two females remaining. This study describes the structure and molecular characteristics of the southern white rhinoceros ovaries, which are the closest relative to the northern white rhinoceros. The research reveals the presence of follicles in all ovaries, even in advanced age. Interestingly, the study also finds mitotically active and pluripotent cells with germ cell properties in the neonatal ovaries, providing an opportunity for fertility preservation. Utilizing ovaries from stillborn and adult rhinoceros can contribute to advanced assisted reproductive technologies, and studying neonatal ovaries of other endangered species is crucial for conservation efforts.