Changes in oestradiol, progesterone and testosterone concentrations in follicular fluid and in the micromorphology of preovulatory bovine follicles relative to the peak of luteinizing hormone

Abstract

Preovulatory bovine follicles (n = 58) were collected at different times after the onset of standing oestrus when cows would allow mounting until shortly before ovulation, which occurred 24 +/- 1.4 h after the peak level of LH in the peripheral blood. Non-atretic antral follicles (n = 71) of 3-20 mm were also collected from cows during the luteal phase of the oestrous cycle. The follicular fluid was aspirated for the radioimmunoassay of oestradiol-17 beta, progesterone and testosterone. The follicular wall was examined micromorphologically. Follicular fluid steroid levels were compared in 2-h periods relative to the LH peak. The development of the preovulatory follicles from onset of oestrus to ovulation can be divided into four phases. Phase 0 (after onset of oestrus but before LH surge) was characterized by a high level of oestradiol (6.05 mumol/l); the levels of progesterone and testosterone were lower (0.387 and 0.165 mumol/l respectively) but higher than in non-atretic luteal follicles of similar size. The theca interna (TI) was wider and the membrana granulosa (MG) cells were larger than those of non-atretic antral follicles. During phase 1 (0-6 h after the LH peak) oestradiol remained constant but at a lower level, progesterone increased (0.727 mumol/l) and testosterone was higher from 0 to 2h after the LH peak (0.241 mumol/l). The TI was 40% wider, whereas the size of the MG cells remained the same. In phase 2 (6-20 h after the LH peak) the level of oestradiol dropped rapidly during the period from 6 to 10 h, that of progesterone decreased to the same level as in phase 0 and that of testosterone was low (0.031 mumol/l). The width of the TI decreased to that of preovulatory follicles in phase 0 and the MG cells were slightly larger. In phase 3 (20 h after the LH peak until ovulation) the level of oestradiol decreased further (0.461 mumol/l) and that of testosterone remained low. Progesterone increased to the highest levels observed (1.51 mumol/l), however, and this coincided with a 39% increase in the size of the MG cells, whereas the width of the TI remained the same as in the preceding phases 0 and 2. In phase 3 the basement membrane began to disintegrate and phagocytic cells could be observed. This points to a simultaneous functional and morphological luteinization. It is suggested that these changes in follicular steroid levels and micromorphology are regulated by the preovulatory LH peak.

Effects of monoclonal antibody against PMSG administered shortly after the preovulatory LH surge on time and number of ovulations in PMSG/PG-treated cows

“…The study was carried out from September to January with 64 Dutch-Friesian and Meuse-Rhine-Yssel heifers which were distributed at random to the experimental groups. After at least three observed normal oestrous cycles on pasture, the heifers were housed indoors in groups of 8 animals under conditions which ensured normal ovarian cyclicity; this housing and detection of oestrus were as described previously (Dieleman et a!, 1983b (Dieleman et a!, 1986). The control group consisted of 28 cows not treated with anti-PMSG.…”

“…The ovaries of 57 animals were recovered by ovariectomy (Dieleman et a!, 1983b) at set intervals after the maximum of the LH surge, around the expected time of ovulation, i.e. at 22,24,26,28 and 30 h after the LH peak respectively.…”

The hormonal control of begging and early aggressive behavior: Experiments in black-headed gull chicks

“…DHT levels were estimated on the basis of the cross reactivity of the antibody for T with DHT (see below). For methods and evaluation of the radioimmunoassays used, see Dieleman et al (1983) for testosterone, and Dieleman and Bevers (1987) for 17h-estradiol.…”

Social Stimuli, Testosterone, and Aggression in Gull Chicks: Support for the Challenge Hypothesis

“…We measured testosterone concentrations by radioimmunoassay as described by Verjans, Cooke, de Jong, de Jong, and van der Molen (1973) with the modifications described by Dieleman, Kruip, Fontijne, and de Jong (1983). We used two different aliquots (range 5-200 l) to test for parallelity, which were extracted with n-hexane: diethylether (4:1, v/v).…”