Heterogeneity in the luteal population following superovulation with pregnant mare serum gonadotrophin and human chorionic gonadotrophin in the sheep.
In order to investigate the development and possible heterogeneity in the luteal population following superovulation, anoestrous ewes were induced to ovulate using progestagen priming followed by injections of pregnant mare serum gonadotrophin (1000 IU) and hCG (1000 IU). Ovaries were recovered from ewes on each of days 2, 4, 6, 8, 10, 12 and 15, and the weight, progesterone content, 125I-labelled hCG binding and progesterone synthesis in vitro of the individual corpora lutea measured. The results obtained showed that plasma progesterone concentrations on the day of slaughter were significantly correlated with time (P less than 0.05), total weight of luteal tissue (P less than 0.001) and number of corpora lutea (P less than 0.05). The number of corpora lutea recovered per animal ranged from two to 12 and was significantly (P less than 0.05) correlated with the day after hCG injection until day 10. There was much variation between individual corpora lutea, particularly in terms of weight and progesterone content, although both were significantly (P less than 0.001) correlated with day of recovery until day 10. 125I-labelled hCG binding was significantly (P less than 0.001) correlated with time until day 15. There was a significant (P less than 0.001) effect of age of the tissue on progesterone production in vitro, with output declining throughout the luteal phase. These results show that the number of corpora lutea induced by superovulation in anoestrous ewes was very variable, and suggest that ovulation may have continued to occur during the luteal phase.(ABSTRACT TRUNCATED AT 250 WORDS)
Hunter
M G
MG
AFRC Research Group on Hormones and Farm Animal Reproduction, University of Nottingham Faculty of Agricultural Science, Loughborough.
Southee
J A
JA
D000780:Anestrus; D000818:Animals; D006063:Chorionic Gonadotropin / Q000494:pharmacology*; D003338:Corpus Luteum / Q000187:drug effects* / Q000502:physiology; D005260:Female; D006064:Gonadotropins, Equine / Q000494:pharmacology*; D010060:Ovulation / Q000187:drug effects*; D011374:Progesterone / Q000097:blood; D012756:Sheep / Q000502:physiology*; D013480:Superovulation / Q000187:drug effects*; D013997:Time Factors
D006063:Chorionic Gonadotropin; D006064:Gonadotropins, Equine; D011374:Progesterone