Borderline vaginas
Introduction
The vaginas that lie in the border area between the embryonic yolk sac and the allantois are called **border** (from the Latin *limitatio -* “limitation”).
They are located between the rectum and the parietal peritoneum, covering the area of the peritoneum where large blood vessels are located and the ureter and fallopian tube pass through. Border vaginas are lined with endothelium of blood vessels. When the yolk sac splits, a boundary membrane is formed on the embryo. In some embryos, the yolk sac is retained, resulting in the formation of so-called vaginal remnants. This may cause atrophy of the internal uterine layer, which can subsequently lead to the development of inflammatory processes.
Structure
The structure of the border vaginal membranes depends on the stage of their development. Young striated tissues that form the membrane are characterized by a special arrangement of intermediate filaments between the myofibrils. The shell often contains tissue of ectodermal origin. On the inner surface of the wall, the fold of the inner shell is very well developed. The unilateral ovary is an outgrowth of the outer germinal layer of the intermediate body. Epithelioid plates extend from the shell of the internal body of the ovary (they cover the wall of the communication channel). The stratified epithelium of the membrane is absent. The epithelium of young membranes has rather light nuclei and a layer of chromaffin or chromatic chromatin. The nucleus is multilobed. Chromopine substance is absent. The mucous glands have a spindle-shaped shape, among them there are long and large tubular formations. Connective tissue fibers are oriented longitudinally and often alternate with mesenchymal histiocytes. The cells of the inner layers are characterized by the presence of full maturation.
In older membranes, the number of cells in the inner layer increases. Connective tissue expands and includes varying lengths of fibrous bundles and a network of polymorphically changing cells. The epithelial layer is represented by a continuous multilayered layer of cells. Its quantity is getting smaller. Glial cells can be found between the layers of epithelium. There are several of them, sometimes they are quite large and form areas of connective tissue. The cells contain both delicate shoots and individual plates resembling muscle or glandular structures. Rarely located lymphofollicles are quite common. Sometimes here you can notice islands of infantilization of the hypodytic glands. The Rouget-Neumann cavity is assembled directly subperitoneally from symmetrically located fascia of the inguinal and circumflex iliac intestines, which pass into each other before entering the final part of the small pelvis. Gastric folds are present in the cavity on both sides.
The embryonic membranes bear the load caused by gravitational aging: under the influence of gravity, some organs and tissues shrink, while others increase in size. As the baby's membranes mature, the external organs gradually change their location in relation to the internal organs, which is what happens during the prenatal period. When the fetus is positioned with its legs forward, the right wing moves upward under