GROWTH AND DEVELOPMENT OP FOLLICLES IN DIFFERENT PHASES OF THE ESTROUS-CYCLE IN COWS IN RELATION TO THE PRESENCE OF THE CORPUS-LUTEUM AND AN ESTROGEN-DOMINANT FOLLICLE

In this work recruition and growth of follicles and quality of the lar gest ones were determined and compared in the individual stages of the bovine oestrous cycle (stages I, II, In: acid IV - days 1-4, 5-10, 11 -17 and 18-21, respectively) in relation to the presence of the corpus luteum and an oestrogen-dominant follicle on the ovary. The maximum p roportions of smalt (< 49 mm), medium-sized (5.0-9.9 mm) and large (> 10 mm) follicles were observed in stages IV (93.4%), I(16.6%) and III (4.88), respectively. The results of our study revealed the presence o f the large oestrogen-dominant follicle that have negative effects upo n the presence of another large follicle on the ovary and upon the rec ruition of small (< 4.9 mm) follicles. On the contrary, the presence o f a large oestrogen-dominant follicle positively influenced the occurr ence of 5-9.9 mm follicles in all stages of the cycle. No effects of t he CL were observed upon the presence of medium-sized and large follic les. Although the differences were insignificant, negative effects of the CL were observed in relation to the occurrence of small (< 4.9 mm) follicles.