Abstract
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.
Highlights
Preantral ovarian follicles (PAOF) comprise about 90% of all follicular population present in the mammalian ovary[1]
The aim of the study was to evaluate the effect of recombinant bovine somatotropin and thyroxine (T4) on survival and growth of bovine preantral ovarian follicles (PAOF) cultured in vitro
The presence of recombinant bovine somatotropin (rbST) maintains the rate of morphologically normal follicles during the culture for seven days, but it does not exert beneficial effects on its ultrastructural integrity and oocyte and follicular growth
Summary
Preantral ovarian follicles (PAOF) comprise about 90% of all follicular population present in the mammalian ovary[1]. In the physiological process occurring in vivo, more than 99% of them undergo atresia[2]. The increase in the reproductive potential of mammalian females is related to the maximum use of these ovarian follicles, enabled by the application of biotechniques. In this context, the manipulation of oocytes enclosed in preantral ovarian follicles stands out[3]. The follicular development process is dependent on hormones and growth factors that act mainly in oocytes and granulosa cells (GC), promoting its development[4]. Studies that aim to obtain a culture system that allows the maintenance of the viability of these follicles and their posterior development are necessary
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