Changes in Number of Granulosa Cells, Follicular Fluid Levels and Diameter of Oocytes during Folliculogenesis in Pre-pubertal Gilts at Marketing Weight

The follicles (1.8 to 7.8 mm in diameter) were recovered from the ovaries in marketed pigs and the number of granulosa cells, the diameter of oocytes obtained from different development stages of the follicles and follicular fluid levels were determined. Correlations between size measurements and cell counts as well as the diameter of antral follicles and oocytes were also investigated. The results indicated that, while expanding in size, follicle numbers decreased with a greater atretic proportion. Granulosa cells increased in numbers continuously and remained unchanged beyond the size of 200 mm in non-atretic follicles, whereas a sudden drop of granulosa counts was observed in atretic follicles. Follicular fluid, on the other hand, linearly increased its volume with follicle size and differed little between those of non-atretic and atretic follicles. Diameters of oocytes in non-atretic follicles increased to its maximum when follicles expanded to 150 mm and maintained its size during later follicular expansion. It is concluded that, for in vitro culture, the optimal size of porcine follicle should be between 150 to 180 mm if they are collected from pre-pubertal gilts of marketing size slaughtered in an abattoir. (Asian-Aust. J. Anim. Sci. 2004. Vol 17, No. 12 : 1647-1651)