STUDIES ON THE PRODUCTION OF PREGNANT MAR E SERUM GONADOTROPIN WITH RESPECT TO HISTOLOGICAL-FINDINGS AND FETAL DEVELOPMENT

Thirty-five mares were slaughtered during pregnancy for a variety of r easons such as lameness and malignant diseases. The majority of them h ad zero or low serum titres of PMSG. These animals were used to invest igate the reasons for these low titres or absence of detectable PMSG d uring day 56 and 105 of pregnancy. PMSG collection was started at day 60 of pregnancy and continued until days 95-100. The serum concentrati on of PMSG was analysed with respect to the relevant reproductive date s, the results of histological examination of the endometrial cups and the stage of foetal development. A relation was observed between the number of pregnancies and the serum concentration of PMSG. There was a lso an indication of an association between foetal development and the serum concentration of PMSG. The status of the endometrial cups is de pendent on the stage of pregnancy. Mares with no detectable serum PMSG had a similar ovarian status and structure to those with normal PMSG levels. The histological findings of the endometrial cups are describe d.