AJP - Endocrinology and Metabolism, Vol 243, Issue 4 325-E331, Copyright © 1982 by American Physiological Society
Follicle dominance and ovarian asymmetry after luteectomy in rhesus monkeys
A. L. Goodman, M. J. Koering, W. E. Nixon, R. F. Williams and G. D. Hodgen
Previous work demonstrated that asymmetrical ovarian activity accompanies
morphological asymmetry during the ovarian cycle in rhesus and cynomolgus
macaques. This study was designed to determine whether functional ovarian
asymmetry could be used to detect the upcoming dominant follicle (DF) even
before it was grossly visible. Revealing a latent DF in this manner would
permit a better estimate of the time when dominance of the follicle
selected to ovulate is attained. To accomplish this, rhesus monkeys were
luteectomized at midluteal phase to synchronize subsequent follicle growth,
and 4 or 8 days later either the ipsilateral or contralateral ovary was
removed. Unilateral ablation at day 4 (when no DF is grossly apparent) of
either ovary produced symmetrical responses: the interval from luteectomy
(CLX) to the next luteinizing hormone (LH) surge was extended by about 4
days in both groups (P less than 0.01), i.e., from about 12.5 days to 16.7
+/- 1.6 and 17.0 +/- 1.5 days (mean +/- SE). In contrast, hemiovariectomy
at day 8 produced markedly divergent asymmetrical responses. Removal of the
ipsilateral ovary 8 days after CLX did not affect the timing of the next LH
surge (13.2 +/- 0.6 days), which ordinarily occurs about 12.5 days after
CLX alone. However, ablation of the contralateral ovary (bearing the next
DF) on day 8 extended the interval from CLX to the next LH surge from about
12.5 to 26.6 +/- 1.3 days. These findings indicate that, during the normal
ovarian cycle when menses occurs 2--4 days after luteolysis, the follicle
destined to ovulate becomes dominant between the 2nd and 6th day and that
attainment of dominance signals the completion of a follicle selection
process that begins or resumes promptly after luteolysis.
