Transforming growth factor alpha (TGFAlpha) in testicular development of the prepubertal boar

Abstract

Whether intratesticular levels of transforming growth factor alpha (TGFA) are associated with cellular and structural changes that occur within the testis during puberty in boars was investigated. Immunostaining and morphometric procedures were used to characterize age-related changes in cell distribution and density of TGFA. The aspects of the proliferation of Leydig and Sertoli ceus and the presence of TGFA were determined by the inimunocytochemical and the morphometric analyses of the porcine testes. The animals in this study numbered 36 (comprised of six age groups containing 6 boars from 6 different litters). At birth, litterniates were assigned to one of six age groups, which included Day 1, Day 14, Day 28, Day 56, Day 112 or Day 170. AU boars less than Day 170 were considered prepubertal, while Day 170 boars were considered pubertal. The body, paired testis and paired epididymal weights each increased in proportion to change in age. The greatest increase of all weights occurred from Day 112 to Day 170. The number of Leydig and Sertoli cells increased with age across all animals. Even though there was a slight decline in Leydig cell numbers from Day 14 to 28, the number of Leydig cells and diameter of the seminiferous tubules increased as the boars aged. The testis was inununopositive for TGFA at each age group. TGFA was immunolocalized in greater than 90% of the Leydig cells; however, the intensity of TGFA staining in these cells decreased with age. In contrast, the degree of immunolocalization and intensity increased in Sertoli cells as animals progressed from Day 1 to Day 170. The stimulatoxy and/or inhibitory effects of TGFA could be important to normal function of testicular cells. The changes in both number, size and function of testicular cells (Leydig and Sertoli cells) throughout development may be modulated by the changing amounts (or actions ?) of TGFA. The temporal changes in appearance and distribution of testicular TGFA may influence the development of the male reproductive system.