SPATIAL-DISTRIBUTION OF PROGESTERONE IN BOVINE UTERUS IN RELATION TO CORPUS-LUTEUM LOCATION AND FUNCTION

Distribution of progesterone was determined in the uterus of dairy cows at different luteal stages of the estrous cycle. Tissue samples were excised at different and spatially distinct portions of the uterine horn (proximal, medial, distal) and body of the uterus. A significant (P< 0.05) interaction was observed between uterine horn and CL progesterone level groups. Concentrations of progesterone were higher in tissues of the uterine horn ipsilateral to the CL vs the body or contralateral horn but only from cows with high CL progesterone content. Progesterone concentrations were significantly higher (P<0.05) in the proximal, medial and distal parts of the uterine horn ipsilateral to the corpus luteum than in any part of the contralateral horn and body of the uterus with high CL progesterone group. There was no significant interaction between uterine horn and sites. Concentrations did not differ among sites within either horn, regardless of CL activity. A positive relationship existed between uterine progesterone levels (means of all sites) in the ipsilateral (r=0.75) and contralateral (r=0.67) horns and CL progesterone levels. No apparent correlation was found between uterine tissue concentrations and ovarian follicular fluid or granulosa tissue concentrations. The results indicated that uterine tissue progesterone levels depend on CL activity (content) and that localized uterine increases are due to location (horn ipsilateral to an active CL).