Immunohistochemical localization of bone matrix proteins in the testes of immature and mature cats

Aim: This study was designed to a) determine the differences in the localization and distribution of osteocalcin, osteonectin and osteopontin proteins in cat testes according to maturity stages by immunohistochemical method, b) reveal whether they participate in the structural components of the testis and c) determine their possible roles in the reproductive physiology of the male cat. Materials and Methods: In the presented study, a total of 30 testicular ttissue samples were obtained from healthy male cats of different ages and breeds, brought for castration to the Dicle University Veterinary Faculty Polyclinic and some private veterinary clinics in Diyarbakır, were used. The tissues were fixed with 10% neutral buffered formalin solution and then processed into paraffin blocks by routine histological stages. Serial sections of 5 micrometer thickness were taken from the paraffin blocks. Some of the sections were stained with Crossman's triple staining and the other part with immunohistochemistry. Results: As a result of the immunohistochemical findings obtained from the study, it was determined that osteocalcin, osteonectin and osteopontin proteins were localized and distributed in different densities in the cells of the immature and mature testes. It was determined that osteocalcin, osteonectin and osteopontin proteins showed a strong immunoreaction in Sertoli, Leydig and some germ cells in the immature, and a weak immunoreaction in the ductus deferens. However, osteopontin immunoreactivity was weak to moderate in epididymis epithelial cells, while it was negative in connective tissue cells. In spermatocytes of adult testes, osteonectin and osteopontin immunoreaction intensity was found to be strong, while osteocalcin was at moderate levels. In Sertoli and Leydig cells, osteocalcin formed a moderate immunoreaction, while osteonectin and osteopontin were determined to be almost nonexistent. In addition, osteocalcin immunoreactivity was observed to be strong in epididymis epithelial cells, while it was found to be at a moderate level together with osteonectin in ductus deferens epithelial cells. Conclusion: It was observed that osteocalcin, osteonectin and osteopontin proteins were expressed in different densities in the testis, epididymis and deferens ducts of kittens and adult cats. It was revealed that there was no difference between cat breeds in terms of staining intensity and distribution of the observed expression. When the findings were examined, it was suggested that osteocalcin, osteonectin and osteopontin may have possible functions in the differentiation and proliferation of germ cells, in the regulation of direct testosterone secretion in Leydig cells and in the metabolic and mitotic activities of cells in the seminiferous tubule wall.