this study investigated the effect of gnrh analogues on inducing ovulation of dominant follicle (df)and subsequent corpus luteum (cl) lifespan in the presence of norgestomet implant in holstein heifers. onday 6 to 8 of the estrous cycle (day 0 of the experiment), all heifers (n=15) received norgestomet implantfollowed by prostaglandin injection on days 0 and 1. on day 4, group 1 (n=4) and 2 (n=...

Administration of gonadotropin-releasing hormone (GnRH) induces a surge of luteinizing hormone and ovulation in a variety of species, including human beings. Our objectives were to determine the effect of follicle size at the time of ovulation on corpus luteum function and establishment and maintenance of pregnancy in cows in which ovulation was either spontaneous or induced with GnRH. GnRH-ind...

BACKGROUND The purpose of this study was to assess the accuracy of ovulation detection by the DuoFertility(®) monitor compared with transvaginal ultrasound in infertile women with regular menstrual cycles. METHODS Eight infertile patients, aged 27-40 years, with a body mass index of 19-29, regular menses, normal ovaries on pelvic ultrasound scan, and normal early follicular luteinizing hormon...

The mid-cycle surge of luteinizing hormone (LH) induces ovulation, a process during which a fertilizable oocyte is released from a mature ovarian follicle. Although ovulation is a physiologically well-characterized event, the underlying molecular pathways remain poorly understood. Progesterone receptor (PGR), which mediates the biological effects of the steroid hormone progesterone, has emerged...

We previously reported that ovulation rate, but not pregnancy rate or litter size at d 30 after mating, was enhanced by treatment with P.G. 600 (400 IU of PMSG and 200 IU of hCG, Intervet America, Inc., Millsboro, DE) in gilts fed the orally active progestin, altrenogest (Matrix, Intervet America, Inc.) to synchronize estrus. We hypothesized that in addition to increasing ovulation rate, P.G. 6...

Gonadotropin-releasing hormone (GnRH) has been used to warrant the success of artificial insemination by accurately timing occurrence of ovulation. In practical conditions, GnRH may be administered too late, after ovulation, with an eventual reduction in pregnancy rate. The aim of this study was to investigate whether GnRH administration after ovulation would have a negative effect on luteal fu...

One method to overcome the difficulties involved in reproducing first generation Senegalese sole that are born in captivity (F1) is to obtain gametes by stripping and then using them for artificial fertilization. The aim of this paper was to determine an appropriate protocol for hormonal induction of ovulation and artificial fertilization. To induce ovulation, two different GnRHa administration...

Female mammals are classified into spontaneous and induced ovulators based on the mechanism eliciting ovulation. Ovulation in spontaneous species (e.g., human, sheep, cattle, horse, pigs, and most rodents) occurs at regular intervals and depends upon the circulating estradiol. However, in induced ovulators (e.g., rabbits, ferrets, cats, and camelids), ovulation is associated with coitus. In the...

Cell-to-cell communication was characterized in cumulus-oocyte complexes from rat ovarian follicles before and after ovulation. Numerous, small gap junctional contacts were present between cumulus cells and oocytes before ovulation. The gap junction are formed on the oocyte surface by cumulus cell processes that transverse the zona pellucida and contact the oolemma. The entire cumulus mass was ...

Progesterone receptors appear in granuloma cells of preovulatory follicles after the midcycle gonadotropin surge, suggesting important local actions of progesterone during ovulation in primates. Steroid reduction and replacement during the gonadotropin surge in macaques was used to evaluate the role of progesterone in the ovulatory process. Animals received gonadotropins to induce development o...