Study of preantral follicle population in situ and after mechanical isolation from caprine ovaries at different reproductive stages

The purposes of this study were to estimate the population of caprine prean tral follicles, and to evaluate quantitatively and qualitatively the effici ency of a specific mechanical method for the isolation of preantral follicl es from mixed breed goats at different reproductive stages. On average, 37, 636+/-4277 preantral follicles were present in goat ovaries, and 13,631+/-2 399 preantral follicles were obtained after isolation. The number of preant ral follicles isolated or in situ was not significantly affected by the rep roductive stage. The mean recovery rate per ovary ([number of isolated foll icles/number of in situ follicles] X 100) of isolated follicles was 36.2%. The distribution of follicles in situ was 67.8% primordial, 25.8% primary a nd 6.4% secondary; the respective distribution after isolation was 93.8%, 5 .2% and 1.0%. In this study, many polyovular follicles were also observed, mainly in prepubertal goat ovaries. Histological analysis showed that few p reantral follicles were atretic in situ (4.83% +/- 0.35) or after the isola tion procedure (4.67% +/- 0.65) in the three reproductive stages. The perce ntage of atretic follicles was not affected either by the mechanical method or by the reproductive stage. It is concluded that a large number of prean tral follicles can be successfully isolated mechanically, with a high recov ery rare and a low rate of follicular atresia, irrespective of the reproduc tive stage of the caprine female. (C) 1999 Elsevier Science B.V. All rights reserved.