The number of goat trophoblastic binucleate cells, the incidence of their migration and the formation of trinucleate and syncytial cells in the maternal uterine epithelial layer was estimated quantitatively using transmission electron microscopy between 14 and 23 days postcoitum (dpc). Binucleate cells were first observed at 18 dpc and their proportions increased rapidly from less than 1 per cent to 16 per cent by 19 dpc and 22 per cent by 23 dpc. The appearance of trinucleate cells within the maternal uterine epithelial layer coincided with evidence of migration and fusion of binucleate cells with individual uterine epithelial cells, and an increased death rate among the other uninucleate uterine epithelial cells. There was also a slight increase in the incidence of intraepithelial lymphocytes close to the trinucleate cells. The quantitative studies uphold the hypothesis that at implantation in the goat, placental trinucleate cells and their subsequent multinucleate syncytial plaque derivatives are fetomaternal hybrid tissue formed by fusion of a binucleate cell(s) with a single uterine epithelial cell.

Animals↗

PubMedDate not supplied

Blastocyst-endometrial interactions and protein synthesis during pre-implantation development in the pig studied in vitro.

A co-culture technique is described for the study in vitro of interactions between elongated blastocyst tissue and endometrium in the pig. Culture conditions which were optimal for blastocyst protein synthesis were determined and tissue survival was assessed after 48 h in culture. A defined medium was adopted consisting of medium 199 supplemented with insulin and antibiotics. Blastocyst protein synthesis measured by labelled leucine incorporation was not enhanced by the addition of serum, suggesting either that it was not required for optimal protein synthesis ar that active substances of maternal (endometrial) origin were already adsorbed on to embryonic tissues. Endometrial explants co-cultured with blastocyst tissue enhanced blastocyst protein synthesis approximately fourfold when intrinsic protein synthesis was low, but had little effect if it was already high. Blastocyst explants in which protein synthesis was enhanced by co-culture with endometrium demonstrated an increased synthesis of prealbumin proteins with molecular weights of 25 000 to 30 000.

Animals↗

PubMedDate not supplied

The influence of protein hormones and conceptus extracts on sheep lymphocyte transformation induced in vitro.

The study describes the effects of crude extracts of the fetal membranes of day 25 sheep conceptuses and of certain purified protein hormones and pregnancy-associated antigen on the mitogen-induced response of sheep peripheral blood lymphocytes (PBL) in vitro. A dose-dependent suppression of the proliferative response of PBL to phytohaemagglutinin, pokeweed mitogen and concanavalin-A was seen when cultures were supplemented with a soluble extract of fetal membranes. Preliminary characterization suggested that the suppressive agent was heat stable and dialysable. These properties distinguished the immunosuppressive component of membrane extracts from ovine pregnancy-associated antigen, which is heat labile and non-dialysable. However, both high and low molecular weight forms of ovine pregnancy associated antigen were also shown to inhibit lymphocyte transformation in vitro. In contrast, ovine luteinizing hormone, prolactin, growth hormone and human placental lactogen were inactive. The findings are consistent with the hypothesis that immunosuppressive substances are present in the gravid uterus during early pregnancy in the sheep.

Animals↗