Umbilicus

“ In the majority of cases, no effort is made toward assistance until the body is born as far as the umbilicus, partly because of the difficulty of taking hold of the child securely before that time, and partly because the perineum is not likely to be fully 299distended, in which case a serious tear would probably result. ”

“ Blizard presented to the Royal College of Surgeons a very instructive specimen of a human Ovum having a sarcomatous and calculous placenta, which had been expelled at three months and a half, by a patient who had miscarried three times within the three previous months.
There is also in the same college a magnificent specimen of a solid Ovum, of the size of a hen’s egg and shape. A small portion of the shell of this Ovum having been cut off, the embryo is seen, of the size of a common fly, within the cavity, which may be just large enough to admit the top of a man’s thumb. ”

“ This gentleman having observed an ovum still alive in the uterus of a ewe, which was a short time advanced in gestation, removed it and placed it upon a warm glass plate exposed to the rays of the sun, and attentively examined it with the microscope. The beatings of the heart became more lively. He noticed the blood arise to the surface of the chorion from the fœtus, there ramify plentifully, and by anastomosing vessels, return to two of the larger trunks which were the veins of the embryo. ”

“ The maternal uterus and the embryonic allantois send out finger-like processes into each other which interlock, and the tissue between the abundant bloodvessels in them thins down to such an extent that nutritive material, peptones and carbohydrates, and oxygen also, diffuse freely through it from mother to foetus,* and carbon dioxide, water, and urea from the foetus to the mother. The structure thus formed by the union of the wall of the maternal uterus, allantois, and the intermediate structures is called the placenta. ”

“ The placenta when developed is a membrane composed largely of blood vessels, entirely surrounding the embryo and is attached to the womb near the top. At this point the umbilical cord, which connects with the child at a point called the navel, merges into and becomes a part of the placenta. These thousands of cells, under the control of some invisible agency or law within the mother and the embryo, begin to arrange themselves in layers and groups. In this way the rudimentary organs one by one, step by step, begin to form. ”

“ The function of the placenta is partly to supply nutrition, partly to serve as an organ of respiration for the embryo, whose lungs are, of course, not functional, and partly it acts in the same way as the kidney does in after life, by excreting certain products. From the placenta the embryo derives those food elements at first provided by the secretion of the uterine glands. Afterwards these elements are supplied by cells which lie between the fœtal villi and the blood of the mother. ”

“ From the abdomen of the embryo arises an organ, the allantois, which is destined to carry the blood-vessels of the embryo to the placenta, and at the same time to give rise to the formation of the latter. In the placenta the blood-vessels of the embryo are separated from those of the mother by walls so thin that the nutritive juices of the maternal blood transude into the venous blood of the embryo, as well as combined oxygen in the blood necessary for its respiration. ”

“ PLACENTA (Lat. for a cake) , in anatomy, the organ by which the embryo is nourished within the womb of its mother. When the young one is born the placenta and membranes come away as the "afterbirth." In human anatomy the organ is a circular disk about seven or eight inches in diameter and one and a quarter inches in thickness at its centre, while at its margin it is very thin and is continuous with the foetal membranes. It weighs about a pound. ”

“ At a later period, indeed, when the embryo is larger, when the ovum or conception has contracted adhesions with the uterus, and the umbilical vessels have penetrated the caruncles, the chorion extends further, and at its extremities on either side, and as it were in a couple of appendices, there is a certain fluid of a yellow colour, which you might call excrementitious, kept separate and distinct.
The human conception scarcely differs in any respect from an egg during the first months of pregnancy. ”

“ During gestation the unborn infant has been supplied with air and nourishment by the mother. An organ called the Placenta, a spongy growth of [16] blood vessels, develops on the inner point of the womb. To this organ the growing foetus is moored by a species of cable, the Umbilical Cord. This cord, also made up mainly of blood vessels, carries the blood of the foetus to and from the Placenta, absorbing it through the thin walls which separate it from the mother's blood. Only through her blood can the mother influence the child, since the Umbilical Cord contains no nerves. ”

“ The purpose of the umbillical cord is to contain and support the umbillical arteries and veins through which the fetus obtains nourishment from the placental substance, and through which the return blood flows. The rich red arterial blood is carried from the placenta to the fetus, and is then distributed over the body of the fetus, nourishing and building it up; the dark venous blood, laden with the waste products of the body of the fetus, is carried back to the placenta, there to be repurified and rendered again rich and nourishing. ”

“ That the embryo probably lives in utero in virtue of its own life-principle, even through the entire period of gestation, (51, 56, and 58,) is rendered probable by many facts related by unimpeached authorities, which go to prove that when the whole intact Ovum has been expelled at an advanced period of gestation, or at the natural termination of that period, the fœtus has continued to live, and the circulation of the blood has not ceased for an instant during a space of time of from nine minutes to a quarter of an hour. ”

“ If such be the case, can it have the power of retaining the germ in the womb, when on the most minute examination of the young, I could not detect, by cicatrice or line of abrasion on any part of the abdomen, that they ever possessed umbilical vessels, or had been in any way nourished by a placenta? Let us take into consideration the small size of the animal found in the pouch, its utter helplessness, its slight power of motion, and its firm attachment to the nipple. The more it is in the embryonic state the firmer is its attachment to the mother ”

“ The comparative growth of the fœtus infinitely surpasses that of its whole future existence. But the exact age of uterine embryos, and of abortives, is, in some degree, conjectural. Before the seventeenth day after conception, its rudiments are not even visible to the naked eye: the glary ovum has then slidden down from the ovarium, through one of the lateral tubes into the womb. The size of an abortion, comprehending the fœtus, its membranes, waters, and placenta, at the end of six weeks, does not exceed in size that of a pigeon’s or hen’s, and in three months, a goose’s egg. ”

“ On the seventh of August, 1827, he read a paper on extrauterine pregnancy, in which he seemed anxious to establish the opinion, from the historical detail of cases, that ventral or abdominal pregnancy never originally occurred; that tubal or uterine pregnancy had previously existed in cases where the child was found in the cavity of the abdomen, the tube or uterus having been ruptured or ulcerated so as to allow the escape of the fetus from its original location into the peritoneal cavity. ”

“ Fig. 163. Diagrammatic longitudinal section of an ovum of a Guinea-pig and the adjacent uterine walls at an advanced stage of pregnancy. (After Bischoff.)
yk. inverted yolk-sack (umbilical vesicle) formed of an external hypoblastic layer (shaded) and an internal vascular layer (black) . At the end of this layer is placed the sinus terminalis; all. allantois; pl. placenta.
The external shaded parts are the uterine walls.
The Human Embryo. Our knowledge as to the early development of the human embryo is in an unsatisfactory state. ”

“ The Ovum.—Pathological changes of the ovum itself, of the embryo, of the surrounding membranes are less frequent as primary causes of abortion, and they are of less importance to the practitioner as being in no way amenable to treatment. When they do occur they usually lead to expulsion in the earlier months.
Those conditions liable to lead to abortion are especially diseases of the [p. 490] chorion, placenta, and umbilical cord, rarely of the amnion, the embryo itself, or the amniotic fluid. ”

“ The life of the fetus, therefore, is absolutely contingent upon an uninterrupted, two-way flow of blood through the cord.
The Fetus. In tracing the development of the ovum after its implantation in the uterine lining, we begin, as previously stated, with a shaggy-looking vesicle, containing fluid, with a clump of cells hanging toward the centre from their point of attachment on the inner surface of the sac. This clump develops into the embryo. ”

“ By the thirtieth day the tiny embryo is already one-third of an inch big, and were it practicable, which, of course, it is not, to remove it living from its bed of tissue in the mother’s womb and examine it, even with the naked eye, and still more with a magnifying glass, it would be possible to see the rudiments of the legs, head and arms which are to be. ”

“ In one point of view, more especially, is the present diseased Ovum particularly interesting to me; for it exhibits the most distinct proof that what I call the cortex of the Ovum, and which others have, without direct evidence, considered as a membrane of the uterus, is, in good truth, a natural covering of the Ovum. It is this very natural covering of the Ovum which is liable, from disease, to become fleshy, opaque, vascular, and lastly coriaceous, thereby cutting short the supply, or accretion of substance to the fœtus, and thus destroying its life and producing abortion. ”

“ The internal cavity is laid open so as to exhibit an embryo in each half of the Ovum, the one being double the size of the other. The smaller embryo is about as large as a good-sized house-fly. The cord of the largest embryo is nearly an inch and a half long, sacculent, and expanding towards the abdomen so as to form the only covering of that cavity. The cord of the smaller embryo is half an inch in length and filiform. ”

“ The amniotic fluid performs many important duties. Perhaps the first, in point of time, is to provide sufficient room for the embryo to grow in. Later, as the fluid increases, it permits the fetus to move freely, and yet renders the movements less noticeable to the mother. ”

“ By the end of the third month, or twelfth week, centres of ossification have appeared in most of the bones, the fingers and toes are separated and bear nails in the form of fine membranes; the umbilical cord has definite form, has increased in length and begun to twist. The neck is longer, teeth are forming and the eyes have lids. The amnion and chorion are now in contact, and the villi have disappeared excepting at one point where a small, but complete placenta has developed. The embryo is about 9 centimetres long and weighs about 30 grams. ”

“ The latter succeeds immediately to the former; beginning at the moment when the new being is grafted on the maternal womb, and continuing until its expulsion from thence at the full period of gestation. It follows, therefore, that the Embryonic or former state is that in which the new being is as yet, without any direct or indirect communication with the mother, and still less so with external objects. This state persists for about two weeks after fecundation, during which the Embryo continues to derive its nourishment from the cortical membrane of the Ovum. (Boer, Soemmering, Plagge, myself.) ”

“ Mere arrest of development of a part may arise from accidental disease of the embryo; hence vital organs are left out, or portions of organs, like the dividing walls of the heart, are omitted. Sometimes an older fetus is inclosed in the body of another, each having started independently from a separate ovum, but the one having become embedded in the semifluid mass of the other and having developed there simultaneously with it, but not so largely nor perfectly. ”

“ The uterus, that during its nine months' evolution had been increasing enormously in all its elements, has in six weeks to undergo an involution that will restore it to its pregravid condition. The allied organs share in their measure in the change, all the systems of the body feel the influence, and especially the mammary glands take on their function of providing milk for the nutriment of the new-born infant. A patient with some latent flaw in her constitution may pass the test of pregnancy and labour with success, only to succumb during the puerperium. ”