Effect of Somatotropin and Thyroxine on the in Vitro Development of Bovine Preantral Follicles

Abstract

The aim of the study was to evaluate the effect of recombinant bovine somatotropin (rbST) and thyroxine (T4) on survival and growth of bovine preantral ovarian follicles (PAOF) cultured in vitro. Ovarian fragments were collected in local abattoirs and immediately fixed for classical histology and transmission electron microscopy (non-cultured control). The other fragments were then cultured in situ for seven days in minimum essential medium alone (MEM+ - cultured control) or in the presence of 1,000 ng/mL rbST and 20 ng/mL T4, isolated or associated. After seven days, there was a reduction (P<0.05) in the percentage of normal follicles in MEM+ alone or with T4. In oocyte diameter, there was a reduction in MEM+ alone. There was no influence (P>0.01) of the medium used on the follicular diameter of the PAOF cultured for seven days. Ultrastructural analysis showed cell damage. In conclusion, the presence of rbST maintains the rate of morphologically normal follicles during the culture for seven days (observed by optical microscopy), but it does not exert beneficial effects on its ultrastructural integrity and oocyte and follicular growth.

Effect of somatotropin on survival and diameter of bovine preantral follicles

“…In cattle, the best result reported for this species so far was the formation of the antral cavity after in vitro culture of advanced secondary follicles (Gutierrez et al, 2000). In the attempt to develop an efficient culture system, different substances (hormones and growth factors) have been tested in the in vitro culture of PAOF (Silva et al, 2018). Among the hormones that have been the target of research in the area of animal reproduction is Somatotropin (ST), also known as Growth Hormone (GH).…”