MALFORMATIONS OF TIIE FOETUS.
It is impossible to give in a concise article, such as is suited to a cyclopmdia, a complete description of all the various malformations of the foetus. I must refer to my manual, published in Dutch, under the title De nzens chelyke Vrucht beschouwd in hare regelmatige en onregelnzatige ontwikkeling, Amsterdam, 1840 en 1842, and to my Tabula ad illustran dam Embryo-genesin Honzinis et Manzmalium, where a more full and accurate description of the various kinds of malformations of the fcetus is to be found. I can give here only a short description of the principal groups, as an introduction to the doctrine of the malfor mations of the fcetus.
Mende even observed in a very well formed child absence of one of the umbilical arteries, together with an unusual course of the umbi lical vein, which, instead of communicating with the vena portm, opened immediately into the right auricle of the heart.
7. Increased number of the vessels of the cord. — A double umbilical vein is constantly to be found in the Quadrumana of the New World (Rudolphi). In Man the unusual plurality of the umbilical vessels is but ap parent, as it is produced by the persistence of the vasa omphalo-mescnterica.
8. Persistence of the umbilical vesicle, is a natural condition in the Ouistiti (Rudolphi), and occurs as a deviation in Man. Sometimes it is only its duct that remains united with the small intestine, forming what we call a diverticulunz.
9. Constriction of the umbilical cord occurs at the point where the cord penetrates into the abdomen. In the constricted part the vessels, although remarkably narrowed, still allow in some measure the circulation of the blood. The cord is thereby contorted into a spiral. The death of the fcetus is its usual effect (Landsberger). .F7g.147. of the second volume of this Cyclopmdia gives a represent.• ation of this constriction of the umbilical cord.
10. The umbilical cord too thick. — Its dia meter varies from 11-21 inches. This is, is general, the consequence of an uncommon accumulation of the Whartonian gelatine, or of an oedematous conditon. In ono of the I. Non-closure of the anterior Part of the Body.
Emhryogenesis teaches us, that the tho racic and abdominal cavities are originally open, and close themselves by degrees at a later period of uterine life. The late ossifica tion of the sternum and of the pubic bones is the result of this original disposition. The points of ossification are not formed in the broad cartilaginous basis of the sternum be fore the fourth or fifth month of pregnancy ; they are in the beginning widely separated from each other by broad intervals in the middle, and approach later to fuse into one central osseous piece. This mode of formation explains some of the original malformations of the sternum; namely, its abnormal breadth, the openings which are found in it, and its separation into two parts. These two last conditions denote, that the sternum is the compound of two lateral halves fused together (Rathke). The separation of the sternum into two parts usually accompanies ectopia of the thoracic and abdominal viscera.
Sometimes, although the thoracic viscera are enclosed in their cavity, the original divi sion of the sternum remains, and is covered up by the skin (Ficker, Serres, Winslow). In some rare cases, the whole or the largest part of the sternum is absent in individuals with no other deformity (Von Ammon). In most of these cases the manubrium alone is present (Wiedemann). In some, but very rare, cases the anterior wall of the thoracic and abdomi nal cavity is only closed by the skin, and its osseous and fleshy parts are completely defi cient (R. G. Mayne). The lines alba is, as well as the sternum, the cicatrix of a cleft existing at an earlier period. This explains its abnormal breadth, obvious in those cases in which the wall of the abdomen has been closed at a later period than usual. An ex ample of it is given in my Tabula XXIV. fig. 4. Sometimes the muscles of the anterior abdominal wall are wanting, in which case the convolutions of the intestines may be seen and felt through the skin (Von Ammon). The thoracic and abdominal cavities being open in the first periods of embryogenesis, if this condition persists abnormally, it produces ectopia of the thoracic and abdominal viscera.