Immunohistochemical expression of markers of immaturity in Sertoli and seminal cells in canine testicular atrophy

During maturation from fetal to adult testis, both Sertoli cells (SCs) and germ cells (GCs) switch from an immature to a mature immunophenotype. Immature canine SCs express cytokeratins (CKs), desmin (DES), vimentin (VIM), anti-Müllerian hormone (AMH) and inhibin (INH)-α, while mature SCs retain only expression of VIM. Immature GCs express placental alkaline phosphatase (PLAP), which is lost in spermatocytes. Re-expression of markers of immaturity has been observed in human atrophic testes and in human and canine testicular tumours. In human medicine, testicular atrophy is considered a risk factor for testicular cancer. In the present study 13 canine atrophic testes were examined immunohistochemically. VIM was expressed in the SCs of all cases, while CK, DES, INH-α and AMH were expressed in a variable percentage of SCs in two, five, five and eight cases, respectively. PLAP was expressed by single GCs in one case. Markers of immaturity are therefore expressed by SCs and GCs in canine atrophic testes. Similar results were reported previously in canine testicular neoplasia, suggesting that testicular atrophy may represent a risk factor for tumour development in the dog.