HOME HELP CONTACT US SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by WILSON, C. A. Articles by McNEILLY, A. S. Search for Related Content PubMed Articles by WILSON, C. A. Articles by McNEILLY, A. S.

Experiments were carried out on 4 day cyclic rats or immature rats induced to ovulate by administration of pregnant mare serum gonadotrophin. Removal of the ovaries and adrenal glands at 17.00 h of pro-oestrus, i.e. after the critical period, prevented the appearance of the surge of LH. Sham-operation or removal of only one of the sets of glands had no effect. This indicates that the preovulatory increase in the concentration of oestradiol is not solely responsible for the surge of LH; the presence of a steroid, secreted by the ovaries and adrenal glands in the late afternoon of pro-oestrus, is also required.

Attempts were made to reinstate the surge of LH in ovariectomized, adrenalectomized rats by administration of one of the steroids normally secreted in late pro-oestrus. Corticosterone, 20- and 20β-hydroxy-4-pregnen-3-one and 17-hydroxyprogesterone all had no effect. Progesterone injected at the time of the operation stimulated the release of LH but only after the plasma concentration had reached its maximum 3–5 h after injection. Testosterone also stimulated the release of LH some hours after administration.