MUCOUS MEMBRANE OF THE CERVIX.
Robin states that this retains the structure which it had before preg nancy. There is a separation of its elements, the intervals being filled with transparent amorphous matter, with a paucity of granulations.
The superficial and sub-epithelial capillaries of the corporeal mucous membrane cease abruptly at the cervix.
Lott insists on peculiar epithelial changes. These consist in a change from the cylindrical to the pavement form, and in a multiplication, es pecially in the folds of the membrane.
The cervical mucosa is not a decidua, and hence, after delivery, is sharply distinguished from any new membrane.
Changes in the Uterine Vessels and Nerves.
Arteries.—These increase in volume, length and even number. Jacque mier states that this increase in length is not from straightening out of folds, since the vessels are as tortuous at the end of pregnancy as before it. The uterine arteries are a little larger than the ovarian. Forming an extensive plexus in the broad ligaments, these vessels suddenly increase in volume as they penetrate the uterus at its sides. They are nearer the peritoneal than the mucous surfice, except in the placental region; and they anastomose with each other and with their fellows of the opposite side. Large numbers pass in until they reach the mucosa where they end in a capillary plexus. Those that go to the inter-utero-placental mucosa are longer and larger than the others, and are called utero placental arteries. They all have fibro-cellular sheaths; and the capil
laries communicate with the veins.
Veins. —These grow very large. The ovarian veins (Jacquemier) ex ceed in diameter, by 1.17 to 1.5 inches, that of the internal or external iliac vein. Deep in the uterine tissue they form uterine sinuses which intercommunicate. According to KOBiker, besides their normal muscu lar layer with broad circular fibres, they have an internal and external muscular layer with longitudinal fibres. Their walls are thus very thick. KoBiker's views are not now accepted: all believe that the uterine sinuses have a single internal tunic. KOHiker's fibres are but muscular tissue adhering to the veins, changing them into contractile canals. None have valves.
Near the placenta, a great number of these canals approach the internal layer, and are separated therein by a very thin layer of uterine tissue, or only by the mucosa, when they penetrate in the utero-placental mucosa and enter the placenta; they are the utero-placental veins.
The sinus of the middle layer receives veins from the internal and ex ternal layer, and from the decidua, thus changing the uterus into a cavern ous organ; hence the abundant hemorrhage at the moment of delivery.
We have already sufficiently discussed the lymphatics and the nerves.