Analysis of the TGF± (transforming growth factor alpha) expression in germinative cells and the frequency of Sertoli cells in bulls of synthetic breed with deficient seminal quality

Abstract

The transforming growth factor alpha (TGF±) is a molecule from the family of the transforming growth factors and has been pointed out as a probable regulator of testicular development. The hypotheses in the present study was that bulls from synthetic breeds with deficient seminal quality presented different TGF± expression and average number of Sertoli cells when compared to normal bulls. Testicles from six Braford and eight Brangus-Ibagé bulls with and without problems in semen quality were used. The immunohistochemical technique was employed to determine the TGF± expression in seminiferous epithelium and to mark the nucleus of the Sertoli cells with the use of respectively of monoclonal antibody anti-TGF± (Ab-2; Calbiochem) and anti-S100 protein polyclonal antibody (DAKO). The general average of spermatogonia marked by the antibody was different for each breed: 9.2±0.4 for Braford and 11.0±0.3 for Brangus-Ibagé. No difference regarding the expression of TGF± was found between sound and unsound bulls. The average number of Sertoli cells was similar between bull breeds. A smaller Sertoli cell population was found in the sound Brangus-Ibagé bulls, which may be an indication that the origin of the low seminal quality in synthetic bulls should be detached from the embryonic or the early newborn phase when the total number of such cells in adults is established. The understanding of cell interaction in the seminiferous epithelium, involving growth related factors, requires not only the identification of the expression site but also the in vivo meaning to spermiogenesis. The study of the growth factors in the testicle in adult bulls is worth further research in order to understand the regulation of spermiogenesis at the paracrine level in adult animals.