Reproduction in ruminant species is a highly complex biological process requiring a dialogue between the developing conceptus (embryo-fetus and associated placental membranes) and maternal uterus which must be established during the peri-implantation period for pregnancy recognition signaling and regulation of gene expression by uterine epithelial and stromal cells. The uterus provide a microen...

The stock of Os mice studied was maintained in the Department of Animal Genetics, University College London. During the later part of the work, a colony was established at New York University Medical Center from mice kindly sent by Professor Griineberg. Embryos from Os/+ xOs/ + and from Osj + x +1+ matings were examined between the 3rd and 8th day of gestation. Age was determined by the standar...

Studies comparing the regressing corpus luteum with the rescued corpus luteum have demonstrated that human chorionic gonadotrophin (hCG) has effects on cell types that do not express hCG receptors. As progesterone synthesis is hCG dependent and the corpus luteum has been shown to express genomic progesterone receptors, progesterone is a candidate molecule for these paracrine effects. This study...

Repeated superovulation using three treatments of pFSH at intervals of 45 to 55 days during the same breeding season was carried out in 18 Préalpes ewes. The embryos were recovered by surgery after the first two treatments and by slaughter after the last one at Day 6. Three lots of control ewes (n = 5 or 6) receiving the same superovulation treatment were slaughtered respectively at the same ti...

Previous investigations have demonstrated that increased ovarian function during pseudopregnancy in the rat may be associated with alterations of the physical state of membranes. Changes in rigidity of membrane lipids were observed during the formation as well as regression of corpora lutea. The effects of cyclooxygenase inhibitors (indomethacin and acetylsalicylic acid (ASA)) and of selected s...

BACKGROUND The traditional hCG 'trigger' for initiating final oocyte maturation exacerbates ovarian hyperstimulation syndrome (OHSS) in patients with an excessive follicular response because of its sustained stimulatory effect on the corpora lutea. However, a GnRH agonist trigger can produce a short duration endogenous LH surge which is adequate to initiate oocyte maturation, but allows the cor...

The method of parabiosis in rats was used in the analysis of the effects produced by continuous gonadotrophic overstimulation of ovaries. The source of constant gonadotrophin supply was the hypophysis of the castrate member of pairs. The reactor animal was either a hypophysectomized female (I), a male carrying an ovarian graft (II), or a constant-estrus female (III). The essential feature in ea...

The timing of cellular exit from the cell cycle during differentiation is specific for each cell type or lineage. Granulosa cells in the ovary establish quiescence within several hours after the ovulation-inducing luteinizing hormone surge, whereas they undergo differentiation into corpora lutea. The expression of Cdk inhibitors p21 and p27 is up-regulated during this process, suggesting that t...

Leucocytes vary in type and number during the lifespan of a corpus luteum. The aim of this study was to determine whether there is an increase in the number of lymphocytes and macrophages as a result of local proliferation. Bovine corpora lutea were classified into stages of development, secretion and regression. A new double immunolabelling method was established for nuclear Ki-67 antigen (a m...