An immunohistochemical study of normal and neoplastic canine sertoli cells.

Immunohistochemical studies of human fetal Sertoli cells (SCs) have shown transient expression of cytokeratin (CK) and desmin (DES) that is replaced after birth by expression of vimentin (VIM) and inhibin-α (INH-α). Human Sertoli cell tumours (SCTs) are characterized by re-expression of CK and DES. The aim of the present study was to evaluate immunohistochemically the expression of VIM, INH-α, CK and DES in normal and neoplastic canine SCs. Normal testicular tissue from three adult dogs, one 6-month-old puppy and two neonatal pups was examined in addition to samples from 21 canine SCTs. VIM was not expressed by neonatal SCs, but was present in SCs from the puppy, the adult dogs and in all SCTs. Conversely, INH-α was expressed by neonatal SCs and most SCTs, but not by normal SCs of adult dogs and the puppy. DES and CK were expressed only by some SCTs. These results show that, contrary to findings in man, canine SCs do not express VIM at the time of birth. SCs from neonatal dogs do express INH-α, but such expression was lost in the puppy and the adult dogs. Canine SCs therefore differ from human SCs, as expression of INH-α characterizes immature SCs, whereas the expression of VIM characterizes mature SCs. Canine SCTs may express CK and DES, suggesting that the neoplastic cells undergo de-differentiation during transformation.