. The anatomical record. Anatomy; Anatomy. 152 The Anatomical Eecord. formed, this musculature is replaced by connective tissue, the ostia venosa, then being called annuli fibrosi. At the same time, however, that the musculature of the sulcus coronarius is being replaced by con- nective tissue, the septum intermedium, which was originally composed of connective tissue, becomes invaded by musculature from the sinus, and through it the muscular continuity between the atria and ventricles, which would otherwise be destroyed, remains established. In hearts of pig embryos of 15 mm. we begin to see
. The anatomical record. Anatomy; Anatomy. 152 The Anatomical Eecord. formed, this musculature is replaced by connective tissue, the ostia venosa, then being called annuli fibrosi. At the same time, however, that the musculature of the sulcus coronarius is being replaced by con- nective tissue, the septum intermedium, which was originally composed of connective tissue, becomes invaded by musculature from the sinus, and through it the muscular continuity between the atria and ventricles, which would otherwise be destroyed, remains established. In hearts of pig embryos of 15 mm. we begin to see the sinus musculature breaking. Fig. 2. Fig. 2. The division of the right venous valve into the Eustachian and Thebesian valves. The septum superius has reached the septum intermedium. through the septum intermedium. In a 20 mm. pig this musculature has formed a small strand which passes forward just above the ven- tricular septum, and in a little later stage we see the bifurcation of the strand, one branch passing beneath the endocardium to the right side of the ventricular septum and the other to the left. In the ventricular portion we recognize the forerunners of the ultimate Purkinje fibres, but not so in the atrial portion. This difference remains throughout life (Tawara). The differences in structure of the musculature of various parts of the foetal heart have also made it possible to trace the fate of the conus. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Bardeen, Charles Russell, 1871-1935, ed; Boyden, Edward A. (Edward Allen), 1886-1976; Bremer, John Lewis, 1874- ed; Hardesty, Irving, b. 1866, ed; American Association of Anatomists; American Society of Zoologists; Wistar Institute of Anatomy and Biology. [New York, etc. ] A. R. Liss [etc. ]
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