Fetal Leydig cell dedifferentiation and redifferentiation

It is well accepted that the Leydig cells in the fetal testis (fetal Leydig cells, FLCs) are functionally distinct from the Leydig cells in the postnatal testis (adult Leydig cells, ALCs). We performed lineage tracing of FLCs using transgenic mice and revealed that a part of FLCs dedifferentiate from fetal to neonatal stages. Moreover, the dedifferentiated cells contribute to the peritubular myoid cells (PTMCs) and the vascular pericytes (VPs). In this project, FLCs and their descendant cells were labeled by EGFP using FLC-specific Cre (mFLE-Cre) mice, and we identified EGFP expression in two distinct cell populations in the postnatal day 10 (P10) testes; the undifferentiated mesenchymal cells (EGFP-plus-Lam-minus) and the PTMCs and VPs (EGFP-plus-Lam-plus). These two cell populations were isolated by cell sorting and subjected to mRNA-sequence analyses.