Studies on the physiology of the maternal placenta in the rat

Abstract

Although a great many investigators have made adequate studies on the maternal placenta from the morphogenetic point of view, little attention has so far been given to the humoral conditions which make the formation of the placenta materna possible. Experimental investigations of the problems of placental physiology have as yet been few, and leave unanswered many important questions. Which are the factors determining the life span of the placenta, and what is responsible for its ageing ? In what way are the pregnancy changes influenced by the three structures —maternal placenta, foetal placenta, and embryo—present during gestation, and what is the role of each ? Recent advances in the physiology of reproduction have made it possible to attempt the elucidation of these problems under unusually favourable conditions. Of great importance was the observation of Leo Loeb that the maternal placenta could be produced experimentally in the rodent. Furthermore, we have reported experiments which showed that the embryos could be removed from the pregnant rat and mouse without interfering with the development of either the foetal or the maternal placenta. These facts, together with the important progress of the past few years in the physiology of the female sex hormones in general, have formed the basis for our present studies, and have enabled us to elucidate some of the problems indicated above.