in calibre as soon as they leave the umbilical cord to divide upon the concave surface of the placenta. This is constant in all cases, but more marked when the vessels are of large size, and when, instead of radiating from the cord, as is the rule in central insertion, the insertion is markedly eccentric, marginal, or velamentous, so that lateral branches are given off from one main trunk. This increase in volume is the only example of the kind in the entire animal kingdom: the rule being a conical diminution in size as the distance is increased. Once dilated, the artery never returns to the intrafunicular size, but remains upon the placental surface, nearly double in volume. This enlargement is not apparent in the earlier stages of embryo life, but commences about the time that the arteries begin to lengthen faster than the vein, so as to return upon themselves and wind around the vein. It is evident, too, in those rare cases where but one artery is present,* and in those even as rare, where no anas tomosis exists between the arteries. Should both arteries unite into one in the cord and then again separate, the dilatation is still as marked upon the placental surface. This increase in volume is sometimes evident in the umbilical vein in its first branches upon the surface, and is occasionally of such size as to present a regular varix. As it is only apparent in all cases towards the close or in the latter half of embryo life, Hyrtl as * In these exceptional cases where but one umbilical artery is present, the other terminates as the hypogastric in the body of the foetus. When this condition exists Hyrtl has made the singular observation that the fœtus has always been found of male sex. (PLATE III. fig. 7.) cribes it to a loss of elasticity in the vessel walls; * a loss of elasticity might perhaps be added, which is rendered inservient to the increased demands of the rapidly developing embryo, by securing a retardation of the circulation, whereby the interchange is more fully and perfectly effected. Besides this diffuse dilatation there exists a circumscribed form of dilatation which sometimes amounts to an aneurisma verum. This enlargement is not so constant as the last described, but it is nevertheless very often encountered. They form the so-called "bulbs" of the umbilical arteries which Hyrtl† has described in detail. "Their usual seat is upon the trunk of the umbilical artery, soon after its exit from the cord; it is necessary, however, that the artery make a bend in its course; should it run in a straight direction the 'bulb' is not presented.” When the turn is sudden the dilatation is greater, presenting the form of the "human stomach" with a greater and lesser curvature; the lesser curvature being towards the placental surface. When the artery presents a very tortuous course, a regular chain of bulbs may be seen alternating from one side to the other. The largest reach a length of 10 lines and a breadth of 6. The wall of the bulb is rather thickened than thinned, but "Die reife Placenta hat ihre Rolle ausgespielt; sie ist alt geworden und beginnt mit dem Geburtsact zu sterben; kein Wunder, wenn ihre Arterien eine Altersveränderung erlitten haben, welche auch an anderen Arterien der Greise sich einstellt: Verlängerung, Krümmung und Erweiterung durch verringerte Elasticität" (Hyrtl). Die Bulbi der Placentar Arterien," von Jos. Hyrtl. Vorgelegt in der Sitzung der Mathematisch-Naturwissenschaftlichen Classe der Akademie der Aerzte. Wien, March 6, 1869. presents no histological alteration; displaying the usual short fusiform muscle cells with spare elastic tissue. When Hyrtl first discovered these bulbs of large size he fancied that he had found so many "placental hearts," the eccentrically hypertrophied bulbs of muscular struc ture presenting a similarity to the axillary heart of the chimæra, but the absence of valves at both entry and exit and the indentations at both extremities proved that they were simply dilatations of the arterial trunk. Twice were these bulbs detected in the anastomotic ramus between the two arteries, and once on one of the arteries of twins, and not on either of the other. A rare form of this circumscribed dilatation is that of the shape of the letter S. It occurs when the isthmus between two bulbs on opposite sides also dilates, and the three enlargements form one. Corroded specimens have never displayed them within the parenchyma of the placenta. They stand in no relation to the life or death of the child; they occur as well in monstrosities as in perfectly developed children of both sexes. The most beautiful and marked examples were found in cases of intraparenchymatous fibrinous deposi tions, partially impervious, or in cases of greater or lesser destruction of the cotyledons with plastic exudation, or in the placenta of the marginal ring of fibrine, the annulus fibrosus of Busch already described. The umbilical arteries, finally, are subject to a torsion of their own, also in a spiral manner; in rare cases this torsion reaches such an extent as to obliterate the calibre of the vessels, when their condition becomes, of course pathological. (c) The investing sheath of the amnion presents no difference in structure from the remaining amnion, viz., an inner pavement epithelium, and an outer fibrous layer containing pale, stellate, nucleated cells. At the umbilicus, or rather within a line or two from it, the contrast between the cutis proper and the bluish translucent amnion is very evident, and it is just here that the cord contains capillaries* and nerves. The sheath, moreover, is extremely adherent to the cord, so that its separation is almost impossible. (d) The gelatine of Wharton, which is supposed to be derived from the allantois, but whose real origin is still involved in mystery, consists, as Virchow has shown, of delicate fibrous tissue with stellate cells containing in its meshes a gelatinous albuminous mass, with a certain number of roundish cells of large size, corre sponding to mucous (myxomatous) tissue. Its use is to protect the vessels from compression. (e) The umbilical vesicle really loses but little of its size in ripe placenta, its long diameter measuring, according to Wedl, 3, its short 2 mmr. It is generally of a dirty-yellowish color, somewhat distended, and easily slit up with a needle. On section it is found to consist of relatively thick walls, consisting of connective tissue. Its contents are a fine cellular mass, grouped in larger or smaller opaque nodules. Its situation is erally in close proximity to the cord; sometimes, how ever, it is found at some distance. * Virchow, Cellular Pathologie, p. 87. gen Schott. Die Controversie ü. d. Nerven des Nabelstr. Frankfurt, 1836. Cords of Multiple Births.-In twins the cords are usually separate and distinct, but sometimes a ramus communicans exists between the two. In the two cases of Spaeth, with but a single amnion, the cords were inserted into the centre of the adherent placentæ at only a half inch separation. When the amnion is double the cords may be inserted near each other, or each marginal, into diametrically opposite borders. In 23 such cases of single chorion and double amnion Credé found a velamentous insertion in 5 cases and among these 3 were into the septa of division, but without any anastomosis whatever of the vessels of each. * The Funic Souffle is now generally accepted as a murmur due to pressure upon one or both of the umbil ical arteries. Being rhythmical, and synchronous with the first sound of the heart, it could only originate in the arteries or in the heart itself. That it is not due to valvular lesion of the heart is proven by the fact that it it is not recognized after birth; congenital valvular lesion being among the rarest of rarities in clinical experience. The view of Kiwisch, that it was only one of the sounds of the heart propagated to a distant point, is refuted by the fact that it is only heard in circumscribed and generally small portions of the abdominal surface, whereas a propagated sound may always be traced to its point of greatest intensity. That it is due to pressure of the cord, as upon the thorax or other resist ing portion of the body, is verified by the dangerous *Discovered by Evory Kennedy, 1833. 66 See a paper by the author on Auscultation during Parturition." Cinti. Med. Report, July, 1870. |