Testis (testicle)

Differentiation of the testicle is brought about under the control of the TDF. The testicular cords (chordae testiculares) develop from the gonadal cords and consist of tightly packed germ cells and somatic cells. During differentiation, three main cell types can be distinguished: germ cells, supporting cells (Sertoli), and interstitial cells (Leydig). The germ cells proliferate and develop further to spermatogonia. The supporting cells stay in close contact with the germ cells. They produce a factor which is responsible for the degeneration of the paramesonephric duct in males. The interstitial cells are located in the interstitium, which sits between the testicular cords. These cells produce testosterone. Secretion of testosterone begins during the fetal period and leads to the differentiation of the genital ducts and the formation of the external genitalia.