INTER-UTERO-PLACENTAL MITCOSA.
While the parietal and ovular deciduse lose their elements, especially the vessels, the inter-utero-placental mucosa develops every element, especially the vessels to receive the villosities of the chorion, which are to form the placenta. The capillary vessels enter the mucosa, dilate and become sinuses, the walls of which disappear, thus forming lacume of blood in the mucosa; and into these sinuses the placental villosities dip. The serotina has, thus, a honeycomb or areolar appear ance. These sinuses are continuous with those in the muscularis, but they anastomose about the placenta forming the circular sinus.
The uterine and ovular placenta first hypertrophy, and then atrophy; while the inter-utero-placental mucosa developes until the placenta is formed, and then remains stationary till delivery at term. All are not agreed on this point. Robin states that the uterine decidua is covered with epithelium until term; Friedlander says that it disappears, and that this decidua has a deep layer next to the muscular made up of glandular culs de-sac lined with epithelium, and a superficial, made of larger cells, both round and spindle-shaped. Fatty degeneration attacks all these ele ments at the end of pregnancy.
The ovular decidua becomes thin, and, KoRiker says, is formed, at the end of pregnancy, of round and fusiform cells which, later, become poly gonal and fatty. Robin states that it is changed into a layer covered with
epithelial debris. He also states that the inter-utoro-placental mucosa preserves its epithelium until term. Riker and Friedlander state that the epithelium completely disappears at the end of pregnancy.
The next question is the fall of the decidua at childbirth. Robin states that from the fourth month of pregnancy the uterine decidua becomes loosened from the muscularis, because a soft, gelatinous membrane forms between them, that is, the new uterine mucosa. Hence, at delivery, the muscularis will not be left uncovered, but will have this new mucous mem brane over it. Only the epithelial layer of the utero-placental mucosa will pass off with the placenta, the rest remaining adherent to the uterus.
The phenomena are identical in every part of the mucosa, according to Friedlander. He states that the layer of round cells disappears, the uterus being covered by the layer formed of deep, spindle cells and glandular culs-de-sac, not only over all the uterus, but even over the placental surface. The glandular layer gives origin to the new mucosa, which, he says, is formed only after delivery.
De Sinety does not think that there is a distinct line between the layer made of round cells, and that of glandular cells, but otherwise he agrees with Friedlander.