File:Gray0459.jpg

Fig. 459. Human embryo of about fourteen days, with yolk-sac

(After His.)

The anterior wall of the umbilical orifice are now continuous with the posterior ends of the anterior ventral aorta. With the formation of the tail-fold the posterior parts of the primitive aortse are carried forward in a ventral direction to form the posterior ventral aortae and primary caudal arches. In the pericardial region the two primitive aortse grow together, and fuse to form a single tubular heart (Fig. 460), the posterior end of which receives the two vitelline veins, while from its anterior end the two anterior ventral aortse emerge. The first cephalic arches pass through the mandibular arches, and behind them five additional pairs subsequently develop, so that altogether six pairs of aortic arches are formed; the fifth arches are very transitory vessels connecting the ventral aortse with the dorsal ends of the sixth arches. By the rhythmical contraction of the tubular heart the blood is forced through the aortse and bloodvessels of the vascular area, from which it is returned to the heart by the vitelline veins. This constitutes the vitelline circulation (Fig. 459), and by means of it nutriment is absorbed from the yolk (vitellus.)

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Historic Disclaimer - information about historic embryology pages

Pages where the terms "Historic" (textbooks, papers, people, recommendations) appear on this site, and sections within pages where this disclaimer appears, indicate that the content and scientific understanding are specific to the time of publication. This means that while some scientific descriptions are still accurate, the terminology and interpretation of the developmental mechanisms reflect the understanding at the time of original publication and those of the preceding periods, these terms, interpretations and recommendations may not reflect our current scientific understanding.     (More? Embryology History | Historic Embryology Papers)

iBook - Gray's Embryology

iTunes link | iBooks Store Description - an extract of the embryology content from Anatomy of the Human Body By Henry Gray Philadelphia: Lea & Febiger, 1918. Releases First Edition - Jan 2012 Second Edition - March 2012 Repaired formatting and image display issues related to Pad rotated display and minor editing issues. Print length 169 pages, 41.6 MB, Language English. The current website also includes numerous images from this textbook, see Anatomy of the Human Body by Henry Gray and Category:Gray's 1918 Anatomy. Note the also Historic Disclaimer.

Reference

Gray H. Anatomy of the human body. (1918) Philadelphia: Lea & Febiger.

Cite this page: Hill, M.A. (2024, April 24) Embryology Gray0459.jpg. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/File:Gray0459.jpg

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