Grado de desarrollo del folículo preovulatorio y su relación con el tamaño del cuerpo lúteo y la producción de progesterona en las razas Romosinuano (RS) y Brahman (Br)T0

Abstract

To compare in the preovulatory follicles of bovine females of the Brahman (Br) and Romosinuano (rs) breeds the development of the different follicular components, such as the size of the follicular antrum, the thickness and volume occupied by the granulosa (cg) and theca interna cells (ti) layers and their possible relationships with the deve- lopment of the corpus luteum (cl) and progesterone (P4) production, 5 rs and 5 Br females were used; ultrasound follow-up was performed during 2 estrous cycles and blood serum sampling was carried out to determine progesterone (P4) levels by Elisa, at the third estrus, the ovary containing the preovulatory follicle was removed, and a diametral cut was made on the stigma of the follicle to divide it into 2 equal parts. Histological sections were made of one of the parts and follicular morphometry was determined. Duration of the estrous cycle in Br females ranged between 18 and 21 days, with an average of 19,9 ± 1,6 days and between 18 and 24 with an average of 21,2 ± 1,69 days for rs cows. Estrus duration was 13,9 ± 6,98 and 9,60 ± 4,72 h for rs and Br breeds, respectively. The estrus-ovulation interval was 21,20 ± 5,07 h for the Br breed animals and 24,40 ± 6,43 rs. There were no differences between breeds or in thickness (rs: 55,12 ± 6,46 µm vs. Br: 49,48 ± 17,07 µm) p > 0,05, nor in the volume occupied by the granulosa cells layer (rs: 27,93 ± 6,11 mm3 vs. Br: 25,40 ± 13,85 mm3) of pre-ovulatory follicles; neither in the thickness (rs: 122,50 ± 20,53 µm vs. Br: 129,61 ± 84,85 µm) nor in the volume (rs: 64,97 ± 19,71 mm3 vs. Br: 59,83 ± 25,67 mm3) of the internal theca cells; p < 0,05. The maximum cl development for all the females was observed on day 12,6 ± 4,05 (day 0 = estrus), with an average diameter of 22,92 ± 3,60 mm. For those of the rs breed the maximum diameter was observed on average on day 14,88 ± 3,4, with 23,06 ± 3,9 mm, while for those of the Br breed it was day 10,00 ± 3,16 with an average diameter of 22,75 ± 3,16 mm; at this time the mean progesterone concentration was 5,37 ± 1,38 ng/ml for the rs breed and 5,74 ± 0,89 ng/ml for the Br breed. There were no significant differences between breeds (p-value: 0,5561). It was concluded that there are no differences in the physiological events studied between the studied breeds. Present results, undoubtedly, might serve as basis to future studies in bovines in tropical zones.