Omphal/o: Definition. The chorion and allantois fuse to form the chorioallantoic membrane. The fetal membranes… Par/o, Part/o: Definition. The chorion is a membrane that helps form the fetal portion of the placenta. Innermost layer of the fetal membrane. Term. Gravid/o: Definition. The oral cavity is lined by a mucous membrane (the oral mucosa) consisting of a stratified squamous epithelium, which may or may not be keratinized, and an underlying connective tissue layer, the lamina propria. The yolk sac provides nourishment to the early embryo until the placenta develops. The outermost layer of the placenta, the chorion, comes into contact with the endometrium; it is composed of two layers of cells - inner cytotrophoblast and outer syncytiotrophoblast. While developing in the womb, the chorion is the outermost fetal membrane, the outer layer of what is known as the amniotic sac. It contributes to major regions of the placenta to enhance the availability of components found in … neomembrane: [ mem´brān ] a thin layer of tissue that covers a surface, lines a cavity, or divides a space or organ. Term. It contributes to the development of the placenta. An allantoic cavity is significant in quadrupeds (Figure 5-31). adj., adj mem´branous. An interchange of substances, such as nutrients and oxygen, occurs between the maternal and fetal bloodstreams through the placenta. Pregnancy: Term. Membranous bag that surrounds the fetus before delivery (also called bag of water) ... Outermost layer of the fetal membrane. The chorionic membrane forms finger-like structures called chorionic villi that burrow into the endometrium like tree roots, making up the fetal portion of the placenta. The Chorion is the outermost layer that is the toughest layer. Birth: Term. The name is due to their origin, i.e., the chorionic villi are projected from the outermost fetal membrane called the chorion to increase contact with the maternal blood. alveolar-capillary membrane ( alveolocapillary membrane ) a thin tissue barrier through which gases are exchanged between the alveolar air and the blood in the pulmonary capillaries. Amnion: Definition. The fetal membranes, sometimes called extraembryonic membranes, are tissues that form in the uterus during the first few weeks of development and develop along with the growing embryo. While rupture of this membrane normally occurs at term, preterm rupture can result in increased risk of fetal mortality and … The vessels in the umbilical cord connect the placental circulation with the fetal circulation. The placenta and fetal membranes separate the fetus from the endometrium , the inner layer of the uterine wall. This layer is also called the “fore bag”. The chorionic villi emerge from the chorion, invade the endometrium, and allow transfer of nutrients from maternal blood to fetal blood. BECAUSE WE HAVE 2 LAYERS! Function and failure of the fetal membrane: Modelling the mechanics of the chorion and amnion "The fetal membrane surrounds the fetus during pregnancy and is a thin tissue composed of two layers, the chorion and the amnion. In placental mammals, the umbilical cord (also called the navel string, birth cord or funiculus umbilicalis) is a conduit between the developing embryo or fetus and the placenta.During prenatal development, the umbilical cord is physiologically and genetically part of the fetus and (in humans) normally contains two arteries (the umbilical arteries) and one vein (the umbilical … Bruch's membrane is the innermost layer of the choroid.It is also called the vitreous lamina or Membrane vitriae, because of its glassy microscopic appearance.It is 2–4 μm thick.