Leukocytes, particularly neutrophils, infiltrate into female genital organs after ovulation in both humans and mice. In mice, a female sexual cycle consists of 5 phases: proestrus, estrus, metestrus-1, metestrus-2, and diestrus. Ovulation occurs at estrus; at metestrus-2, a large number of neutrophils infiltrate into the vaginal epithelium accompanied by an increased neutrophil number in vagina...

On February 4, 14 of 28 seasonally anestrous mares were fed .044 mg per kilogram of body weight of an oral progestin, allyl trenbolone (17a-allyl-estratriene 4-9-11, 17/3-ol-3-one) for 12 days. There was no difference (P>.05) between groups for the number of mares exhibiting estrus after treatment or follicular activity during or after treatment. After March 6, 18 mares that had not yet ovulate...

Analyses of ovulation rates in consecutive estrous cycles with multiple-trait and repeated-records animal models resulted in different estimates of heritability. The estimate from the repeated-records model was seen to be approximately the product of the average genetic correlation and the average heritability from the multiple-trait procedure. A simple model is used to show algebraically that ...

Estrous synchrony was tested using 10 pairs of sibling female rats (Rattus norvegicus). A Monte Carlo bootstrap simulation was used to construct random control groups to avoid previous statistical errors and to test for significance when there are irregular cycles. The 10 pairs of females did not exhibit estrous synchrony. The effect of cycle irregularity on the limits of synchrony was analyzed...

Introduction Figure 1 summarizes some key aspects of the bovine estrous cycle. Changes in the 2 key structures on the ovary, the preovulatory follicle and the corpus luteum, are emphasized in this figure. The function of 4 important hormones is also summarized in this figure. Estradiol-17ß from the preovulatory follicle causes the cow to manifest estrus behaviour and have an LH surge. The LH su...

Two experiments were conducted to study the effect of the stage of a spontaneous estrus cycle on milk yield and constituents [somatic cell count (SCC), fat, protein, caseins, lactose, and urea content] and on estrogen receptor-alpha (ERalpha ) and progesterone receptor (PR) immunostaining in the mammary gland. In experiment I, the major components of milk and SCC were monitored weekly in 80 lac...

Previous studies have demonstrated that a number of behaviors change their probability of occurrence during the estrous cycle. Wheel running is known to show estrous-related changes while reports upon intracranial reinforcement (self-stimulation, ICS) have been equivocal. The present studies examined both behaviors to further resolve the underlying behavioral determinants of these estrous effec...

Two volatile constituents of male mouse urine, 2-(sec-butyl)-4,5-dihydrothiazole and dehydro-exo-brevicomin, were synthesized and tested for their ability to induce estrous cycle in female mice (the Whitten effect). The suppression of ovarian cycling activity that resulted from grouping the females was abolished by exposure to normal male urine. The synthetic compounds, when added together in a...

Experiments were designed to test the hypothesis that LHRH receptors in the preoptic area (POA) are of physiological importance for maintaining estrous cyclicity in the rat. Bilateral cannulae were implanted just dorsal to the POA. Estrous cycles were monitored daily by vaginal smears. Antide, a long-acting LHRH antagonist, was infused bilaterally (2.5 micrograms/side) in the POA or the hypotha...

One-hundred and twenty-three ewes were used in three experiments designed to determine whether the regulation of estrus, by administration of either prostaglandin F2 a (PG) to regress corpora lutea or medroxyprogesterone acetate (MAP) to control the length of the estrous cycle, would increase sperm death in the reproductive tract at the ensuing estrus. Ewes were treated either with PG injected ...