FUTUS, in anatomy, a term applied to the offspring of the human subject, or of animals, during its residence in the ute rus. The term of ovum is applied to the foetus, with its membranes and placenta taken altogether. We shall consider, un der this article, the anatomy of the mem branes which cover the foetus during its abode in the uterus ; of the placenta, which forms the medium of connexion between the systems of the mother and child; and of the pregnant uterus itself, since the peculiarities, distinguishing its structure at this time, arise from the re sidence of the foetus in its cavity. The following description applies to the uterus and its contents in the ninth month of gestation. The size of the organ differs much in different individuals ; and this arises principally from varieties in the quantity of the liquor amnii. In shape it is oviform ; the finidus answering to the largest extremity of the egg, and the cervix and os uteri to the small end. It deviates from this regular figure from va rious accidental causes, as it adapts itself to the neighbouring parts, to the attitude of the body, and to the position of the contained child. Parts of the latter can often be distinguished in the living state. The small, or lower end of the uterus, is placed in the pelvis; this contains the greater part of the child's head, and fills up the cavity so completely as to press the bladder against the pubes, and the rectum against the sacrum. The body and fundus of the uterus, containing all the rest of the child and the placenta, is placed in the front of the abdomen, from the pelvis upwards to the epigastric re gion, so as to be under and before all the other bowels. It occupies the whole space from one hip-bone to the other.
The round ligaments, Fallopian tubes, and ovaria, necessarily undergo consider able change in their situation : they be come closely connected to the uterus, as that body in its enlargement extends be tween the two layers of the broad liga ments. The ovaria are particularly dis tinguished after conception by containing a corpus luteum. This is a firm fleshy portion, distinguished by its yellowish gray colour from the rest of the ovary, and considered as a certain proof that con ception has taken place. If there is one child, there is only one corpus luteum; if two children, two of these bodies, &c. The thickness of the pregnant uterus is from one to two-thirds of an inch. The arteries and veins of the uterus are won derfully increased in size in the pregnant state, particularly opposite to the attach ment of the placenta. This change seems
to arise naturally from the important of fice which the vessels have to perform at this period ; viz. the development and nutrition of the fcctus. Anatomists have disputed concerning the muscularity of the uterus ; but Dr. Hunter describes the appearance of the muscular fibres, which are however very faint. The mouth of the uterus is closed, until the time of la bour, by a viscid glutinous substance.
The contents of the pregnant uterus are, the secundines, liquor amnil, and the fcc tus. The former line the uterus, and im mediately cover the child; they form the chain of connexion and communication between the bodies of the mother and child, and carry on that wonderful influ ence upon which the life and health of the child depend. They are divided into navel-string, placenta, and membranes; and, as they are expelled from the uterus after the birth of the child, they are call ed the The navel-string is a cord about two feet long, made of three vessels twisted toge ther, and fixed at one end to the child's navel, at the other to the placenta Its vessels are an umbilical vein and two ar teries : the latter carry blood from the child to the placenta, and the former brings it back again.
Pkcenta. This, with the membranes, makes a complete bag, lining the uterus, and containing the child. It is thick, fleshy, and exceedingly vascular. Its fi gure is round and flat, about an inch thick, and a span in breadth. The outer surface, which adheres to the womb, is rough, tender, and bloody ; the inner is smooth, harder, and marked by the rami fications of the vessels proceeding from the umbilical cord, which is attached to this part. Its substance consists of two parts intimately blended ; viz. an umbili cal, or infantine, and an uterine portion. The former is a continuation of the umbi lical vessels of the fcctus, the latter an ef florescence of the internal surface of the uterus. The fcetal portion, which is by far the largest part, is a regular ramifica tion of the arteries and veins of the navel string into smaller and smaller branches. No communication whatever has been discovered between these vessels and those of the uterus ; so that the mode in which the fcetus.derives its nourishment and growth must be completely hidden from us.