A review of uterine structural modifications that influence conceptus implantation and development in sheep and goats

Evolution of the placenta and viviparity in eutherian animals underscores the need for an intimate relationship between the developing conceptus (embryo/foetus and associated extra-embryonic membranes) and the dam throughout the period of pregnancy. Thus, maternal support is unequivocally important for conceptus survival and development in utero. Under the influence of several pregnancy-associated hormones, the maternal uterine architecture undergoes rapid growth and substantial remodeling early in gestation. These changes are necessary preparations to accommodate and support rapid conceptus development and growth in the later two-thirds of pregnancy. There are species variations in the nature and extent of uterine remodeling during pregnancy. The regulatory influence of these uterine wall modifications on conceptus survival, implantation and placentation in sheep and goats are discussed in this review.