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Follicular development, maturation and atresia during the estrous cycle in gilts expressing high or low ovulation rate

Hui-Wen Yen, University of Nebraska - Lincoln

Abstract

The first experiment characterized changes in the pattern of follicular development and atresia during the follicular phase of the estrous cycle in gilts selected for an index of high ovulation rate and high prenatal survival (White Line-2, WL-2) compared with randomly selected control (White Line-1, WL-1) gilts. Follicular dynamics changed in response to genetic selection over 10 generations. Selected WL-2 gilts develop M2 (5 to 6.9 mm) follicles earlier in the follicular phase and achieve a larger pool of healthy and functional M2 follicles. During the mid to late follicular phase, WL-2 gilts have a more rapid selection and maturation of healthy M2 follicles into large follicles to achieve their ovulation rate advantage over WL-1 gilts. The objective of the second experiment was to use flow cytometric DNA analysis of granulosa cells to evaluate differences in follicular development and atresia during mid follicular phase in gilts having high and low ovulation rates. Pools of healthy large and M2 follicles to d 3.5 of the follicular phase were similar in gilts with high or low ovulation rate. But gilts with high ovulation rate maintained a larger pool of healthy M1 (4 to 4.9 mm) follicles which they select and mature into ovulatory follicles after d 3.5 to achieve their ovulation rate advantage. The third experiment characterized the pattern of follicular development and evaluated the incidence of atresia by flow cytometric DNA analysis during the luteal phase of the estrous cycle in gilts selected for high ovulation rate and randomly selected controls. Different patterns of follicular development and atresia in these two genetic lines suggest alteration of the follicular recruitment process during the luteal phase in response to genetic selection for high ovulation rate. The last experiment evaluated effects of different doses of progesterone on follicular development and gonadotropin profiles during the late luteal to mid follicular phases in gilts selected for high ovulation rate and controls. Progesterone treatments altered the LH pulses and the development of follicles.

Subject Area

Livestock|Anatomy & physiology|Animals

Recommended Citation

Yen, Hui-Wen, "Follicular development, maturation and atresia during the estrous cycle in gilts expressing high or low ovulation rate" (1999). ETD collection for University of Nebraska-Lincoln. AAI9952698.
https://digitalcommons.unl.edu/dissertations/AAI9952698

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