. The comparative anatomy of the domesticated animals. Horses; Veterinary anatomy. THE F(ETU8. 1045 Instead of going to the lungsâwhich do not yet act as respiratory organsâthe blood, being pressed by the contraction of the right ventricle, passes into the aorta by the ductus arteriosus. To sum up, the foetus never receives pure arterial blood iut(j its organs, this being always mixed with venous bloodâthe mixture taking place at several points : 1. By the foramen of Botal. 2. In the aorta by the ductus arteriosus. 3. In the liver by the ductus veiiosns. The head and neck are the parts w
. The comparative anatomy of the domesticated animals. Horses; Veterinary anatomy. THE F(ETU8. 1045 Instead of going to the lungsâwhich do not yet act as respiratory organsâthe blood, being pressed by the contraction of the right ventricle, passes into the aorta by the ductus arteriosus. To sum up, the foetus never receives pure arterial blood iut(j its organs, this being always mixed with venous bloodâthe mixture taking place at several points : 1. By the foramen of Botal. 2. In the aorta by the ductus arteriosus. 3. In the liver by the ductus veiiosns. The head and neck are the parts which receive the purest arterial bloodâa fact that explains the predominanci,' of the anterior o\er the posterior portion of the body of the foetus. At birth, the conditions of existence being suddenly chaniied, marked modifi- cations take place in the circu- latory apparatus. The lungs ^'S- â ^'*^- become the organs of respira- tion, and rai)idly increase in capacity ; the pulmonary artery dilates to give passage to the blood that flows to them; while the ductus arteriosus is obliterated, in order to isolate the arterial from the venous blood. This separation of the two fluids also takes place in the liver by the atrophy of the ductus venosus, and in the heart by the occlusion of the foramen of Botal; though, according to Goubaux, that orifice frequently remains open in young animals. Its persis- tence has also been noted in the human adult. Notwith- standing the presence of this foramen, the circulation can- not be much disturbed; as when the heart contracts, the auricles become isolated by the constriction of the opening and the raising of a valve. (Lymphatic vessels and glands are found at an early period of foetal life, after the blood-circulation has been fully establislied. In connection with these should be mentioned the prevertebral h(Bino-Ujmph glands, which are best observed, however, in the adult animalâand particularly in the Sheep and Ox. They aie small oval
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Keywords: ., bookauthorcha, bookcentury1900, bookdecade1900, booksubjecthorses
