Hormone concentrations temporally associated with contralateral and ipsilateral relationships between the CL and preovulatory follicle during the third follicular wave in heifers

Differences between follicular waves 1 and 2 in patterns of emergence of 2-mm follicles, associated FSH surges, and ovarian vascular perfusion in heifers

“…The preceding FSH concentration on average was decreasing before the FSH nadir at the beginning of surge 1, whereas surge 2 was preceded by basal concentrations. Although not reported in the present study, the decreasing FSH before the FSH nadir of surge 1 apparently represents the declining portion of a minor FSH surge [2,6,29] that occurs in a majority of waves [6]. The beginning nadir of the minor surge occurs 6 days before ovulation with a peak 4 or 5 days before ovulation or during the days that early emergence of 2-mm follicles was demonstrated in the present wave 1.…”

Mechanism for greater frequency of contralateral than ipsilateral relationships between corpus luteum and ovulatory follicle for wave 3 in heifers

“…The results confirmed the following: (1) the number of contralateral follicle-CL relationships is greater than that for ipsilateral relationships in wave 3, (2) the number of waves per IOI is measurably repeatable, (3) increases in LH and estradiol during the ovulatory wave are related to the differences in the beginning of luteolysis among permutations rather than to increased frequency of the contralateral-wave 3 permutation, and (4) FSH surge 3 is temporally associated with the extended luteal phase in three-wave IOIs. The study also revealed the following: (1) the side of ovulation (left or right ovary) was not related to the number of waves per IOI or to the follicle-CL relationship, (2) the beginning of luteolysis (mean day of the beginning of a progressive progesterone decrease) in three-wave IOIs began 2 days later for the contralateral than for the ipsilateral relationships, and (3) a minor FSH surge occurred more frequently in the contralateral than in the ipsilateral relationship in wave 3 but may have reflected the longer interval from wave emergence to ovulation [13]. In regard to point 3, a positive effect of FSH on progesterone has not been demonstrated in vivo, but the bovine CL contains FSH receptors (review [13]).…”

“…The study also revealed the following: (1) the side of ovulation (left or right ovary) was not related to the number of waves per IOI or to the follicle-CL relationship, (2) the beginning of luteolysis (mean day of the beginning of a progressive progesterone decrease) in three-wave IOIs began 2 days later for the contralateral than for the ipsilateral relationships, and (3) a minor FSH surge occurred more frequently in the contralateral than in the ipsilateral relationship in wave 3 but may have reflected the longer interval from wave emergence to ovulation [13]. In regard to point 3, a positive effect of FSH on progesterone has not been demonstrated in vivo, but the bovine CL contains FSH receptors (review [13]). Further study would be needed to determine if there is a functional or coincidental relationship between the simultaneous presence of FSH surge 3 and extension of the luteal phase in three-wave IOIs.…”

“…The need became apparent for study of the endocrinologic differences among the four permutations of ipsilateral versus contralateral relationships of the ovulatory follicle and CL and two versus three waves per IOI [10,12,13]. The most extensive study (n ¼ 87 IOIs) on the temporal associations among changes in hormone concentrations, follicle-CL relationships, and the number of follicular waves per IOI was facilitated by combining control groups from previously reported studies (Fig.…”

“…The most extensive study (n ¼ 87 IOIs) on the temporal associations among changes in hormone concentrations, follicle-CL relationships, and the number of follicular waves per IOI was facilitated by combining control groups from previously reported studies (Fig. 5) [13]. The results confirmed the following: (1) the number of contralateral follicle-CL relationships is greater than that for ipsilateral relationships in wave 3, (2) the number of waves per IOI is measurably repeatable, (3) increases in LH and estradiol during the ovulatory wave are related to the differences in the beginning of luteolysis among permutations rather than to increased frequency of the contralateral-wave 3 permutation, and (4) FSH surge 3 is temporally associated with the extended luteal phase in three-wave IOIs.…”