Growth and development of follicles in different phases of the oestrous cycle in cows in relation to the presence of the corpus luteum and an oestrogen-dominant follicle.
In this work recruition and growth of follicles and quality of the largest ones were determined and compared in the individual stages of the bovine oestrous cycle (stages I, II, III and 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 proportions of small (< 4.9 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 (4.8%), respectively. The results of our study revealed the presence of the large oestrogen-dominant follicle that have negative effects upon the presence of another large follicle on the ovary and upon the recruition of small (< 4.9 mm) follicles. On the contrary, the presence of a large oestrogen-dominant follicle positively influenced the occurrence of 5-9.9 mm follicles in all stages of the cycle. No effects of the CL were observed upon the presence of medium-sized and large follicles. Although the differences were insignificant, negative effects of the CL were observed in relation to the occurrence of small (< 4.9 mm) follicles.
Lazár
L
L
Research Institute of Experimental Veterinary Medicine, Kosice.
Maracek
I
I
D000818:Animals; D002417:Cattle / Q000502:physiology*; D003338:Corpus Luteum / Q000502:physiology*; D004958:Estradiol / Q000378:metabolism; D004967:Estrogens / Q000378:metabolism*; D004971:Estrus / Q000502:physiology*; D005260:Female; D006080:Ovarian Follicle / Q000378:metabolism / Q000502:physiology*; D011374:Progesterone / Q000378:metabolism
D004967:Estrogens; D011374:Progesterone; D004958:Estradiol