Fig. 6. Leydig cell development recovers by neonatal age. Consistent with Dhh recovery, low levels of Cyp17 and Cyp11a1 expression are detectable as early as E14.5. Expression of Cyp17 (A-D) and Cyp11a1 (E-H) recover by E14.5. Recovery of fetal Leydig cell differentiation was assessed by analysing 3ßHSD protein levels at 2 weeks after birth, prior to the proliferation of adult Leydig cells. Two-week-old testis stained for 3ßHSD (I-L) confirms the presence of Leydig cells. Therefore, prior to the proliferation of adult Leydig cells, fetal Leydig cell differentiation is complete.