This project will examine the physiology of the maternal-fetal relationship in developing embryos. The elasmobranchs (sharks, skates and rays) are used since they represent a relatively simple system compared to the more complex mammals and humans. The mother, to varying degrees, provides oxygen and nutrients as well as for the removal of wastes for embryos developing in the uterus. This study will promote a better understanding of the movements of oxygen and carbon dioxide between the mother and embryo, and the mechanisms by which these gases move across tissues in general. Nitrogenous wastes accumulate in the fluids bathing the embryo, and must be eliminated. The manner by which waste products such as ammonia and urea are detoxified and transported will be better understood. Lastly, salts are also regulated by the mother, until the embryo may regulate for itself. The role of the various organs involved in the regulation of salt (kidney, gills and rectal gland) will be described as well as the mechanisms by which salt is transported across tissues. The information gained in this study will be used to provide a model to describe the physiology of the maternal-fetal relationship.
