Expression Of TGFβ And Its Receptors In Adult Human Testis And In Cryptorchid Rats

Transforming growth factor-beta (TGF β ) is multifunctional cytokines, whose numerous cell and tissue activities include cell-cycle control, the regultion of migration, adhesion, multiplication, differentiation, early development, immune functions, the formation of extracellular matrix, and the induction of apoptosis. The previous studies have indicated the stage-specificity distribution of TGF β and their receptors (TGF β -R) in the seminiferous epithelium, suggestting that TGF- β s are physiologically significant molecules in spermatogenesis, which regultes the number of germ cells. Many testicular insults, such as hypophysectomy, cryptorchidism, and administration of gonadotropin- releasing hormone antagonists, can lead to apoptotic germ cell death. It is becoming evident that the process of apoptosis plays an important role in regulting the number of germ cells. However, little is known about whether TGF β participate germ cell apoptosis.Objectives and Methods: To shed light on the function of TGF β s in human testis, the localization of TGF β s in the adult human testis was investigated by immunohistochemical staining method employing specific polyclonal antibodies. To investigate whetherTGF P s induce germ cell apoptosis in experimental cryptorchidism, the apoptosis of spermatogenic cells was detected by means of TUNEL method and the TGFp-RII expression was obsberved with immunohistochemical staining method.Results: l.Both TGF β 1, 3 and their receptors were preponderant in Leydig cells. TGF β 1 could not be detected in seminiferous tubules. TGF β 3 and TGF β -R I were mainly detected in elongating spermatids, while TGF β -R II was predominant in pachytene spermatocytes but weak in spermatogonia , spermatids and Sertoli cells. Only TGF β-RII was detected in Sertoli cells. TGF β 3, TGF β -R I and TGF P -R II showed a staining pattern dependent upon the stage of the seminiferous epithelium cycle. 2. There was significant increase in the expression of TGF β -R II in unilateral undescended testes(UUTs) compared with that in contralateral descended testes(CDTs)(P<0.01). However, there was a significant and time-dependant increase in the apoptotic index(AI) in UUTs than in CDTs in all groups.Conclusions: 1. The presence of TGF β isoforms and their receptors in somatic and germ cells, suggesting that TGF P s and their receptors might be involved in the regulation of meiosis and spermiogenesis in the adult human testis. 2. TGF β -RII may play an important role in spermtogenic cell apoptosis.