DHT potentiates new lobe differentiation from the anterior part of the testis. 3.3- (d-f) or 3.5-year-old males (a-c) were subjected to a bilateral elimination of the first differentiated testis lobe and then treated with DHT (b-f) or with ethanol (a = control). (a), 6 months after surgery, the anterior part of the testis linked to the lung has not yet evolved in a completely differentiated new lobe but histology reveals the presence of primordial germ cells (PGC). (b), 6 months after surgery, in case of exposure to DHT, a newly differentiated testis lobe (RTL) is observed near the lung (Lu). (c), histological section of the lobe shown in (b). A lobule containing cysts with germ cells at different stages is observed. (d), 12 months after surgery, another male exposed to DHT possesses a newly differentiated testis lobe near the lung. As illustrated by the histological section in (e), it contains an anterior zone with early spermatogenic stages (ZES) and a posterior zone with spermatozoa (ZS). F, higher magnification of the ZS showing bundles of spermatozoa (Spz) in a lobule.