Resumen
- The manipulation of oocytes enclosed in preantral follicles (MOEPF) have been used to study the preantral follicles, isolated or not from the ovarian environment, and to develop efficient culture media for their in vitro development. Thus, the objective of the present study was to identify a basic culture media that effectively promotes the in situ development of the bovine preantral follicles. Preantral follicles were obtained from cows (n=6) on local abattoir, on different phases of the estrous cycle. In the lab, the ovarian cortex was chopped into small pieces for short culture time (7 days) in 24-well culture dishes with changes of the medium at each 2 days. The chopped pieces were analyzed on days zero, one and seven. The following media were tested: minimum essential medium (MEM); tissue cellular medium (TCM-199) and McCoy medium, all were supplemented with: HEPES, penicillin, streptomycin, glutamine, bovine serum albumin, transferrin, selenium, insulin and ascorbic acid. The culture was performed at 37 ºC in 5% CO 2 . The pieces were fixed for classic histology and stained by Periodic Acid Schiff (PAS)-hematoxylin and examined by light microscopy (400 X). Statistical analyses for follicles morphology (primordial, primary and secondary) and for classification (normal and degenerated) were done by the chi-square test (χ 2). There was no difference (P>0.05) between MEM and McCoy media in the in situ developed preantral follicles morphology, supporting McLaughlin et al. (2010) and Figueiredo et al. (1994) results, what found that the McCoy and MEM media were effective on isolated preantral follicles, respectively. The in situ cultured preantral follicles on TCM-199 medium showed high level of degeneration and low development. It is concluded that the Mcoy as well the MEM media could be used for the maintainance and development of in vitro cultured bovine preantral follicles.