Normally, the estrus cycle in rats lasts 4-5 days (16), but in the present study a high level of progesterone concentration in LDE and HDE groups enhanced the duration of estrous cycles due to longer duration of diestrus
phase and shorter duration of estrus and proestrus phases in these groups.
The falling progesterone and increasing prolactin concentrations associated with late diestrus
are believed to be responsible for the clinical signs.
22 RHAMM Diestrus
Mesometrial Antimesometrial Epithelium 257.
Proteins secreted by uterine GE of ewes during the first 21 d of gestation have received limited attention; however, total protein and activities of numerous enzymes in uterine secretions are highest during diestrus
or in ovariectomized ewes treated with P4 (Ing and Roberts, 1989).
It has also been reported that resistance against infections of the uterus in estrus is better than that in diestrus
(Canning and Billington, 1983; Rachman et al.
5 ppm THF-diols significantly decreased the numbers of days of diestrus
during the 30-day treatment period.
We analyzed serum samples from 60-day-old offspring euthanized between 0800 (1 hr after lights on) and 1500 hours (6 hr before lights out), in the diestrus
stage of the estrous cycle, for PRL, LH and TSH, and we analyzed anterior pituitaries for PRL and LH by radioimmunoassay, as previously described by Cooper et al.
Animals that had repeated cycles of proestrus, estrus, and diestrus
I and II, in that order, were called "regular cyclers.
The dependent variables were developmental body weight, age at eye opening, anogenital distance, age at VO, age at first diestrus
, wet weight of uterus and ovaries, number of ER-[beta]-positive cells in the AVPV or SON, and volume bf the AVPV or SON.
During fetal life in males and females, pregnancy, or proestrus in females, estradiol levels are significantly higher than during postnatal life in males or prior to puberty and during diestrus
in females (53).
Smears were stained with Giemsa and scored for proestrus, estrus, metestrus, or diestrus
according to classical vaginal smearing technique (15).
The vaginal cytology of some animals revealed intermittent extended periods of diestrus
, whereas others exhibited extended periods of proestrus and/or estrus.