Studies in cattle assessing changes in number and size of antral follicles, concentrations of estradiol, androgens and progesterone in serum and follicular fluid, and numbers of gonadotropin receptors per follicle during repetitive estrous cycles and postpartum anestrus are reviewed. The rate of growth of small follicles (1 to 3 mm) into larger follicles increases as the estrous cycle progresse...

Long-term selection for increased ovulation rate (1984 to 2002) has resulted in a unique ovarian phenotype in the MARC Twinner cattle population. Ovulation rate and frequency of bilateral ovulations were examined by rectal palpation in 29,547 estrous cycles for 3,910 heifers (12 to 18 mo of age) in this population. Bilateral ovulations (one corpus lutuem [CL] on each ovary) were of interest bec...

Interferon tau (IFN-τ) is a ruminant-specific type I IFN secreted by a conceptus before its attachment to the uterus. IFN-τ induces the expression of IFN-stimulated genes (ISGs) via the type I IFN receptor (IFNAR), which is composed of IFNAR1 and IFNAR2 subunits in the endometrium. However, expression patterns of IFNARs during the estrous cycle have not been reported. We hypothesized that the r...

Rats can use a wide spectrum of intra- and extramaze information while navigating through the environment. The current study examined the relative contribution of an intramaze cue with regard to its proximity to the goal. Three experiments were conducted and the impact of intramaze cue removal or rotation on water maze search was examined. In males, the effect of the intramaze cue declined mono...

Depletion of the ovarian reserve is associated with reproductive senescence in mammalian females, and there is a positive relationship between the size of the ovarian reserve and the number of antral follicles on the surface of the ovary. Therefore, we conducted a series of experiments to investigate the influence of stage of the estrous cycle, age, and birth weight on antral follicle counts (A...

For 6 years adult, non-synchronized Hampshire ewes (n=2,5,8,8,9 and 12) and rams (n=6,10,12,11,11 and 9) were maintained separately and released to contiguous pastures having in common a woven-wire fence about 80m long and 1.1m high. Natural estrous cycles were monitored daily by observations of ram-seeking behavior as defined as a ewe being persistent in staying at the common fence with attent...

2-Bromopropane (2BP) has been implicated to be the reason for the mass intoxication of workers at an electronic company in Korea. A case series study indicated that 2BP was the possible causative chemical for reproductive toxicity, causing severe anemia accompanied by amenorrhea among female workers, and azoospermia or oligospermia among male workers. To clarify the effect of 2BP on the female ...

The study aimed at obtaining basic information about estrous cycle in rats treated with dexamethasone, for polycystic ovaries, induced by constant illumination. It was used 30 female rats (Rattus norvegicus albinus) from the lineage Wistar, with 90 days years old, divided according the following groups: Group I rats maintained in a light/dark cycle for 12/12 hours, and after 100 days submitted ...

Oligonucleotide microarrays (GeneChip Bovine Genome Arrays, Affymetrix Inc., Santa Clara, CA) were used to evaluate gene expression profiles in anterior pituitary glands collected from 4 anestrous and 4 cycling postpartum primiparous beef cows to provide insight into genes associated with transition from an anestrous to a cycling status. Tissues were collected 40 to 61 d after calving from anes...