. The comparative anatomy of the domesticated animals. Veterinary anatomy. 916 EMBRYOLOGY. in the auricles; at a point corresponding to it, a septum is developed in their interior which remains incomplete diu-iug the whole of foetal life, being perforated by the foramen of Fig. 443. Botal. With regard to the aortic bulb, it contracts and divides into two vessels, the aorta and pulmonary artery. The arteries are developed partly at the expense of the vessels of the primary circula- tion, and partly in the vascular lamina of the embryo. The heart, when it was only a simple cylindrical tube, pres
. The comparative anatomy of the domesticated animals. Veterinary anatomy. 916 EMBRYOLOGY. in the auricles; at a point corresponding to it, a septum is developed in their interior which remains incomplete diu-iug the whole of foetal life, being perforated by the foramen of Fig. 443. Botal. With regard to the aortic bulb, it contracts and divides into two vessels, the aorta and pulmonary artery. The arteries are developed partly at the expense of the vessels of the primary circula- tion, and partly in the vascular lamina of the embryo. The heart, when it was only a simple cylindrical tube, presented at its anterior extremity two aortic arches, which curved backwards and united to form the single aorta, then the vertebral or common aortae. The aortic arches are situated at the inner face of the two first pharyngeal arches; afterwards more are developed, which are placed within the other pairs of arches, until the number is increased to five, though they never all exist at the same time. Some atrophy, THE EIGHT AURICLE whilc othcrs aro being developed: the two first entirely disappear; the third form the carotids: the fourth the axillary arteries and the arch of the aorta ; the fifth atrophies on the right, and on the left originates the pulmonary artery, the ductus arteriosus, and the aorta. The latter is continued along the spine by the fusion of the two primitive aortae; they present, at their posterior extremity, the pelvic vessels, which are very small, and the umbilical arteries, which are, on the contrary, remarkable for their volume. The peripheral arteries arise, independently of the central vessels, on the interior of the vascular lamina. They appear in the form of solid cellular branches, which are hollowed in the centre by a cavity in which the cells become free. In proportion as these new vessels are developed, the omphalo- mesenteric vessels disappear, until at last there only remain one or two ducts that pass to the umbilical vesicle. The umbilical veins
Size: 1394px × 1792px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorchauveauaauguste18271, bookcentury1800, bookdecade1870
