. The development of the chick; an introduction to embryology . y-nine intersomitic veins and the veins of the Wolffianbody. At first its connection with the duct of Cuvier is bymeans of a network of vessels, which gradually gives place to asingle trunk (cf. Fig. 117). The Splanchnic Veinf^. The ductus venosus is the unpairedvein immediately behind the sinus venosus, formed by fusion ofthe two omphalomesenteric veins. It is fully formed at the stageof 27 somites. Its relations to the liver have already been de-scribed in connection with that organ. Its subsequent changesare described in Chapte
. The development of the chick; an introduction to embryology . y-nine intersomitic veins and the veins of the Wolffianbody. At first its connection with the duct of Cuvier is bymeans of a network of vessels, which gradually gives place to asingle trunk (cf. Fig. 117). The Splanchnic Veinf^. The ductus venosus is the unpairedvein immediately behind the sinus venosus, formed by fusion ofthe two omphalomesenteric veins. It is fully formed at the stageof 27 somites. Its relations to the liver have already been de-scribed in connection with that organ. Its subsequent changesare described in Chapter XII. The vitelline veins are united at about the stage of seventy-two hours by a loop passing over the intestine immediatelybehind the ])ancreas. (8ee Chap. XII.) VII. Thk Bodv-cavity and Mkskxtkries The origin of the dorsal and ventral mesenteries was con-sidered in the section of this chapter dealing with the ali-mentary canal. As noted there, the dorsal mesentery extends 206 THE DEVELOPMENT OF THE CHICK EI-M O/7V certff/. J(fM i 0/?MJi/£- As/A I/mjjjASM. Fig. 117. — Entire ombryo of .5) s, drawn as a transparent a. 1, 2, 3, 4, First, second, third, and fourth aortic arches. Ar.,Artery. A. V., ViteUine artery, cerv. V\., Cervical Hexure. cr. Fl.,Cranial flexur:\ D. C, Duct of Cuvier. D. \., Ductus , lOpiphysis. (!n. \., (iaiifilion of trifreininus. Isth., ex., External jugular vein. Md., Mandibular arch. M. M.,Maxillo-niandihular branch of the trigeniiinis. olf. P., Olfactory , ()])hthahnic branch of the trigeminus. ()t., otocyst. V.,vein. W. \\., A\ing bud. \\ c. Posterior cardinal vein. , Umbilical vein. \ . V., \itelline vein. V. V. p., Posterior vitel-line vein. FROM TWELVE TO THIRTY-SIX SOMITES 207 the entire leniith of the ahnientary oaiial, while tl>e ventralmesentery persists only in the region of the fore-gut and thecloaca. The embi-yonic ])otly-cavity shows two divisions from a Yeryearly stage, viz., (1)
Size: 1407px × 1775px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookiddevelopm, booksubjectbirds
