The development of the heart in shad (Alosa sapadissima, Wilson) : with a note on the classification of teleostean embryos from a morphological standpoint / by H.D. Senior.

  • Senior, H.D.
Date:
1909
Catalogue details

Licence: In copyright

Credit: The development of the heart in shad (Alosa sapadissima, Wilson) : with a note on the classification of teleostean embryos from a morphological standpoint / by H.D. Senior. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    and the roof by the ventral surface of the splanchnic mesoderm. The roof is entirely lined by vascular endothelium. The floor, having no endothelial lining, presents the naked periblast of the yolk to the blood-stream passing over it. Although the mid-sagittal plane on the embryo would fall (except near the anterior pole of the yolk, see Figs. 21 and 22) entirely within the tunnel, it would separate the latter into two unequal parts, of which the left would be greater than the right. The supravitellins sinus, consisting of the tunnel described above, receives blood from the short vena revehens of the liver and dis- charges it into the, somewhat roomy, chamber embracing the anterior pole of the yolk. The liver, at this time, is situated dorsal to the posterior pole of the yolk (see Fig. 2). The chamber at the anterior Fig. 2.—Diagram indicating the arrangement of the principal blood-channels of the recently hatched shad of which the heart is shown in Fig. 1. X 10 diams. Arteries black; veins, and supravitelline sinus, stippled. pole of the yolk, which corresponds in position with the future sinus venosus, is bounded as follows: Posteriorly by the naked anterior pole of the yolk; elsewhere by the portion of the heart-wall im- mediately succeeding the atrium, which is later to form the anterior, wall of the sinus venosus. Venous blood enters the chamber from the jugular and cardinal veins and from the supravitelline sinus, and leaves it by passing through the orifice leading into the atrium. The relation of the yolk to the vascular system is somewhat as follows: While it converts the partially formed sinus venosus and the (subintestinal) supravitelline sinus into a closed passage, capable of retaining and transmitting blood, it, at the same time, delays the formation of the posterior wall of the sinus venosus and of the vessel later to be formed by the vascular endothelium lining the supravitelline sinus.