Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10891653 | Theriogenology | 2015 | 9 Pages |
Abstract
The emergence (first detection) of 2-mm follicles, FSH surges, and ovarian vascular perfusion for follicular wave 1 and surge 1 (n = 26) and wave 2 and surge 2 (n = 25) were studied daily in heifers. The day the future dominant follicle was closest to 5.5 mm was designated Day 0 for each wave. In wave 1, many 2-mm follicles (41%) emerged on Days â5 to â3, whereas FSH surge 1 did not begin until Day â3. Concentration of FSH increased abruptly in 1 day to a peak on the day of maximal number of emerging 2-mm follicles, although the day of maximal number relative to Day 0 differed among individuals. The first emergence of 2-mm follicles in wave 2 occurred concurrently with the first increase in the FSH of surge 2. In wave 1, ovarian resistance to vascular perfusion was negatively correlated (r = â0.48, P < 0.05) with a number of 2-mm follicles on Days â4 to â1 for ovaries that did not contain the preovulatory follicle; vascular perfusion increased with an increase in the number of small follicles. The following hypotheses were supported for wave 1 but not for wave 2: (1) an increase in the number of emerging 2-mm follicles of a follicular wave occurs before the beginning of an increase in FSH, (2) the day of maximal number of emerging 2-mm follicles occurs concurrently with an abrupt FSH increase on different days among individuals, and (3) the association between the number of emerging 2-mm follicles and the extent of ovarian vascular perfusion is positive.
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Authors
O.J. Ginther, M.A.R. Siddiqui, J.M. Baldrighi, C.A. Wolf, J.M. Greene,