Z8600021: Z8600021 uploaded a new version of "File:Gray0459.jpg"

2014-08-23T08:07:09Z

Z8600021 uploaded a new version of "File:Gray0459.jpg"

← Older revision	Revision as of 19:07, 23 August 2014
(No difference)

Z8600021 at 08:06, 23 August 2014

2014-08-23T08:06:17Z

← Older revision		Revision as of 19:06, 23 August 2014
Line 1:		Line 1:
	==Fig. 459. ==		==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.)

2014-08-23T08:02:55Z

New page

==Fig. 459. ==

{{Gray Anatomy}}

[[Category:Historic Embryology]]
[[Category:Gray's 1918 Anatomy]]
[[Category:Human Embryo]]
[[Category:Heart]]