An introduction to the study of embryology / by Alfred C. Haddon.

  • Haddon, Alfred C. (Alfred Cort), 1855-1940.
Date:
1887
Catalogue details

Licence: Public Domain Mark

Credit: An introduction to the study of embryology / by Alfred C. Haddon. Source: Wellcome Collection.

Provider: This material has been provided by University of Bristol Library. The original may be consulted at University of Bristol Library.

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    ductus venosus itself (ductus venosus Arantii) comes to be a small branch of the vena cava (fig. 171, d). The allantoic vein degenerates at the end of foetal life into the solid cord known as the round ligament, and all the venous supply of the liver comes from the portal vein. Beddard finds that there is in the adult Echidna an anterior abdominal (allantoic) vein, which arises from the under surface of the bladder, and passing along the ventral wall of the body, is distributed to the left half of the liver. An anastomosis between the iliac and portal veins is not estab- lished in Mammals. The allantoic arteries arise from the dorsal aorta as branches of s Fig. 171.—Diagrams Illttstrating twe Devklop- MENT OF THE GRKAT VEINS IN MaHUALS. [From Quain after KiiUiker.] A. Plan of the principal veins of the human embryo of about four weeks, or soon after the first formation of the vessels of the liver and the vena cava inferior. B. Hepatic circulation at a somewhat earlier stage. C. Principal veins of the foetus at the time of the first establishment of the placental circulation. D. Hepatic circulation at the same period. az. azygos vein, above p (in C)—the oblique line is the vein by which the hemiazygos joins the azygos vein; ca. posterior cardinal veins; ca'. (in C) the remains of the left cardinal vein by which the superior intercostal veins fall into the left innominate vein; cr. external iliac or crural veins; ci. vena cava inferior; dc. ductus Cuvieri; h. hypogastric or internal iliac veins, in the line of continuation of the primitive cardinal veins; il. the division of the vena cava inferior into the common iliac veins; J. jugular or anterior cardinal veins ; I. ductus venosus; hepatic veins; li. (in C) in dotted lines, the transverse branch of communication between the jugular vein which forms the left innomi- nate vein; m. mesenteric veins; o. vitelUne or omphalo- mesenteric vein ; o'. right vitelline vein; p. portal vein ; J)'?)', vense advehentes; ri. right innominate vein; s. sub- clavian vein; u. allantoic, umbilical or (left) anterior abdominal vein; (in B) the temporary right allantoic vein. the common iliac arteries (figs. 165, Ic, 171, U). On the disap- pearance of the allantois they remain as the hypogastric arteries. Circulation in Ichthyopsida.—Having now described the development of the circulation in the Amniota, it will be neces- sary to briefly refer to the circulation in Ichthyopsida. rig. 165, which represents the embryonic circulation of an Amniote in a diagrammatic manner, will, with a few alterations, serve to illustrate the circulation in Fishes. The vitelline arteries (Am) and the allantoic arteries {All) are not present, and the