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=...

The corpus luteum is an endocrine gland whose limited lifespan is hormonally programmed. This debate article summarizes findings of our research group that challenge the principle that the end of function of the corpus luteum or luteal regression, once triggered, cannot be reversed. Overturning luteal regression by pharmacological manipulations may be of critical significance in designing strat...

The mechanistic events of female infertility have been investigated for over 50 years and despite progress many causes of infertility remain elusive. However, over half of idiopathic infertility issues have been attributed to a defective ovarian tissue responsible for the maintenance of a conceptus, the corpus luteum (CL). Many CL defects are attributed, in part, to abnormal vascularization (an...

Three experiments were conducted to determine the day at which the bovine embryo first affects luteal lifespan and if intrauterine infusion of homogenates of bovine embryos would extend luteal lifespan in nonpregnant heifers. Exp. I was a 2 x 2 factorial design and utilized 23 pregnant or nonbred Holstein heifers that were subjected to embryo removal procedures on day 15 or day 18 postestrus (e...

Intrauterine and intramuscular administration of interferon was tested for effectiveness in extending luteal lifespan in cattle. Intrauterine infusion of 1 mg of recombinant bovine interferon-alpha I1, twice daily, to lactating dairy cows from d 14 to 21 after estrus extended interestrous interval (30.4 +/- 1.91 d versus 24.8 +/- .58 d) and functional lifespan of the corpus luteum (28.4 +/- 2.0...

CRH/urocortin-receptor-binding protein (CRH/UCN-R-BP) mRNAs are dynamically expressed in the primate ovary during the menstrual cycle. Therefore, studies were designed to localize CRH/UCN-R-BP mRNAs to ovarian cell types, quantitate protein expression during the corpus luteum (CL) lifespan, and investigate the role of this system in the macaque ovary at midcycle. Monkey ovaries were removed dur...

In cattle and other species, the corpus luteum plays a central role in the regulation of cyclicity and maintenance of pregnancy. In the absence of fertilization and implantation, the corpus luteum undergoes functional and morphological regression or luteolysis. Luteal regression is initiated in domestic ruminants by surges of prostaglandin F2alpha (PGF2alpha) from the uterus. Despite intensive ...

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=...