# Follicular development of fetal gonads under the skin of adult mice

## TL;DR

Researchers found that subcutaneous transplantation of fetal mouse gonads failed to develop properly due to meiotic defects, but in vitro culture before transplantation restored follicle development and endocrine function.

## Contribution

The study reveals that in vitro culture can rescue meiotic defects in subcutaneously transplanted fetal gonads, enabling folliculogenesis and endocrine recovery.

## Key findings

- Subcutaneously transplanted fetal gonads showed meiotic deficiency, DNA repair defects, and increased apoptosis.
- In vitro culture at 37°C restored meiotic prophase I completion and enabled folliculogenesis after subcutaneous transplantation.
- The findings suggest potential for using in vitro culture to improve endocrine recovery from fetal gonad-like cells.

## Abstract

Adult ovarian tissues or biopsies isolated from patients prior to chemotherapy or irradiation can reconstitute ovarian functions when transplanted either in the abdomen or subcutaneously. Subcutaneously transplantation avoids invasive surgery and potential risks associated with internal procedures. We investigated whether functional ovaries could develop subcutaneously from early E12.5 fetal gonads without entering meiosis in mouse model. Unexpectedly, the subcutaneously transplanted fetal gonads failed to undergo folliculogenesis in the recipient mice. The transplanted gonads experienced meiotic deficiency and exhibited significant defects in DNA repair and recombination, increased apoptosis levels. Meiotic defects in the subcutaneous grafts were partly attributable to variations in temperature and oxygen concentration. However, completion of meiotic prophase I was effectively achieved through in vitro culture of the gonads at 37°C. Subsequently, the in vitro cultured E12.5 gonads, following subcutaneous transplantation, became competent in folliculogenesis, restoring endocrine functions. This finding may have implications for rejuvenating ovarioids from fetal gonad-like cells using pluripotent stem cell technologies, as well as for enhancing endocrine recovery and health span.