11 - IMMUNOLOGICAL STUDIES ON FETO-MATERNAL RELATIONSHIPS IN EQUINE PREGNANCY

Abstract

This chapter discusses immunological studies on feto–maternal relationships in equine pregnancy. The mechanisms that protect the equine fetus or an intrauterine allograft are of particular interest because of the development of the endometrial cups. These structures are unique to the Equidae and comprise a series of small, ulcer-like, and endometrial outgrowths that form a circle around the conceptus in the gravid uterine horn between 40 and 130 days of gestation. The endometrial cups are the source of the equine chorionic gonadotrophin, formerly known as pregnant mare serum gonadotrophin, which is present in varying concentration in the blood of equids during the first half of pregnancy. The high incidence of cytotoxic antibody production in primigravid mares and its temporal relationship to the accumulation of maternal leucocytes around the endometrial cups suggest that these two phenomena represent the humoral and cell-mediated arms of the same maternal response to paternally-inherited major histocompatibility complex (MHC) antigens. The chapter examines this hypothesis and its necessary corollary that endometrial cup cells do, in fact, express paternal MHC antigens. The chapter also discusses the influence of MHC compatibility on endometrial cup development.