Analysis of the spatial-temporal distribution and functional morphology of telocytes in goat testes.

Telocytes (TCs), a distinct interstitial cell population, are increasingly being reported in the male reproductive system. This study aimed to confirm TC presence in goat testes, to characterize their immunophenotype and age-related differences. Testes from one-, two-, and twelve-month-old goats were examined by using transmission electron microscopy (TEM) and double immunofluorescence (DIF) staining. TEM revealed that TCs were widely distributed among peritubular myoid cells (PMC) in testes from 12-month-old goats and exhibited reduced cell bodies and cytoplasm compared to TCs in juvenile goats. Their telopodes (TPs) displayed the characteristic bead-like structure of alternating podomers (Pms) and podoms (Pds). The telopodes were slender and curved, intertwining near collagen bundles and blood vessels and releasing abundant vesicles. DIF staining reliably identified goat testicular TCs as CD34+/vimentin+ cells with elongated processes and spindle- or triangular-shaped bodies. TCs in 12-month-old goats were significantly longer than those in juvenile goats and had more elongated nuclei. They also exhibited markedly more protrusions and were arranged in four or five parallel stromal layers. The DIF findings corroborated the TEM observations. This study provides evidence of age-related morphological and distributional changes in goat testicular TCs, establishing a foundation for understanding their role in maintaining the microenvironmental homeostasis of the testes.