This study was undertaken to establish whether ovulation in humans alternates consistently from right to left ovary in successive cycles and whether the site of ovulation affects the next cycle length or the hormonal profiles. A total of 199 cycles in 80 normally fertile women were studied. The volunteers were monitored with ultrasonography to determine the day and side of ovulation and to calc...

After parturition, the ovary ipsilateral to the side of previous pregnancy exhibits lower functional activity than that exhibited by the contralateral ovary. The local inhibitory effects of the corpus luteum of the previous pregnancy, and/or the presence of a previous gravid uterine horn, may induce the ipsilateral suppression of folliculogenesis. We examined the influence of the side of previo...

MicroRNAs (miRNAs) are post-transcriptional regulators of gene expression that play critical roles in animal development and physiology, though functions for most miRNAs remain unknown. Worms with reduced miRNA biogenesis due to loss of Drosha or Pasha/DGCR8 activity are sterile and fail to ovulate, indicating that miRNAs are required for the process of oocyte maturation and ovulation. Starting...

Because ancestral women could have obtained genetic benefits through extra-pair sex only near ovulation, but paid costs of extra-pair sex throughout the cycle, one might expect selection to have shaped female interest in partners, other than primary partners, to be greater near ovulation than during the luteal phase. Because men would have paid heavier costs if their partners had extra-pair sex...

Radioactive immunoassay (RIA) is a traditional serum hormone assay method, but the application of the method in reproductive studies is limited by the associated radioactivity. The aim of present study was to evaluate the reliability of RIA and to compare its canine serum progesterone concentration determination accuracy to that of the electric chemiluminescence immunoassay (ECLI). In vivo matu...

It is well established that the luteinizing hormone surge triggers ovulation, a dynamic process leading to the release of the mature oocyte from the ovarian follicle. But how this process controlled by LH signaling remains largely unknown in non-mammalian species. In this study, we investigated the roles of nuclear progesterone receptor (npr) in LH-induced ovulation. Our results indicate that t...

Iteroparous mothers often face a trade-off between further investments in current offspring at the expense of the start of the next reproductive cycle. In the strongly seasonal environments at northern latitudes, large herbivores are typically calving in early summer each year to get a long growth season and to hit peak protein levels of vegetation. Late-born offspring are more likely to die si...

A genetic correlation near unity between ovulation rate in heifers and later twinning frequency led to consideration of using measures of ovulation rate in heifers for each estrous cycle, beginning at puberty, to increase accuracy of selection for twinning rate. An initial evaluation with a multiple trait animal model for predicting breeding values included six genetic groups: 1) selected Scand...

OBJECTIVE To describe the LH surge variants in ovulating women and analyze their relationship with the day of ovulation and other hormone levels. DESIGN Secondary analysis of a prospective cohort observational study. SETTING Eight natural family planning clinics. SUBJECTS Normally fertile women (n = 107) over 283 cycles. INTERVENTION(S) Women collected daily first morning urine, charted...

Polycystic Ovarian Syndrome (PCOS), a common disorder of the endocrine system, is diagnosed based on inclusion criteria of an ovulation or oligo-ovulation, clinical signs of hyperandrogenism, and/or presence of polycystic ovaries on ultrasound. Many women with PCOS also have hyperinsulinemia, leading to over production of ovarian androgens. Due to this differential, the use of the insulin-sensi...