. The development of the chick : an introduction to embryology. Embryology; Chickens -- Embryos. CHAPTER XII THE LATER DEVELOPMENT OF THE VASCULAR SYSTEM. I. The Heart. (For an account of the earlier development, see Chapters V and VI.) At the stage of seventy-two hours (Fig. 198), the ventricle consists of a posterior transverse portion and two short parallel Umbs; the right limb is continuous with the bulbus arteriosus from which it may be distinguished by a slight constriction, and the left limb with the atrium. The constriction be- tween the latter is the auricular canal. Between the two l
. The development of the chick : an introduction to embryology. Embryology; Chickens -- Embryos. CHAPTER XII THE LATER DEVELOPMENT OF THE VASCULAR SYSTEM. I. The Heart. (For an account of the earlier development, see Chapters V and VI.) At the stage of seventy-two hours (Fig. 198), the ventricle consists of a posterior transverse portion and two short parallel Umbs; the right limb is continuous with the bulbus arteriosus from which it may be distinguished by a slight constriction, and the left limb with the atrium. The constriction be- tween the latter is the auricular canal. Between the two limbs in the interior of the ventricle is a short bulbo-auricu- lar septum separating the openings of Fig. 198. — Ventral view of bulbus and atrium into the ventricle. A the heart of a chick em- slight groove, the interventricular sulcus, bryo of mm. head that extends backwards and to the right length. (After Greil from ^^,^^ ^^le bulbo-auricular angle, marks Hochstetter.) ^^^ ^.^^ ^^ formation of the future inter- Atr., Atrmm. B. co., , . /t-- -l^r^^ Bulbus cordis, b. V., The ventricular septum (1 ig. 199). constriction between bulbus j^^ Development of the External and ventricle. v.,Au- ^ , riculo-ventricular canal. V., Form of the Heart. We have seen that Ventricle. ^^ the process of development the heart shifts backwards into the thorax. The ventricle undergoes the greatest displacement, owing to its relative freedom of move- ment, and thus comes to lie successively to the right of, and then behind the atrium. A gradual rotation of the ventricular division on its antero-posterior axis accompanies its posterior displacement; and this takes place in such a way that the bulbus is transferred to the mid-ventral line, where it lies between the auricles (Figs. 199 and 200). The auricles arise as lateral expansions of the atrium, the 348. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - colorati
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Keywords: ., bookauthorlilliefrankrat, bookcentury1900, booksubjectembryology
