A system of obstetrics . Diagram. The letters of reference are as in Fig. 106. mentary canal. Meanwhile, the forward growth of the head and theincreasing tncking-in from before backward of the under curve () of the head-fold, shift the heart backward in relation to thebrain so that it comes to lie under the mid-brain (Fig. 109). Atthis time the pleuroperitoneal cavity has appeared: its anterior por-tion divides into right and left extensions, and these branches, grow-ing forward, partially enclose (pp, Figs. 108, 109) the developing Fig. Diagram : pp, anterior extension of pleurope
A system of obstetrics . Diagram. The letters of reference are as in Fig. 106. mentary canal. Meanwhile, the forward growth of the head and theincreasing tncking-in from before backward of the under curve () of the head-fold, shift the heart backward in relation to thebrain so that it comes to lie under the mid-brain (Fig. 109). Atthis time the pleuroperitoneal cavity has appeared: its anterior por-tion divides into right and left extensions, and these branches, grow-ing forward, partially enclose (pp, Figs. 108, 109) the developing Fig. Diagram : pp, anterior extension of pleuroperitoneal cavity; al, pharynx: the other letters of reference are as in Fig. 106. heart. From them the pericardiac cavity is afterward formed. Laterstill, as the neck develops, the heart is shifted farther back in relationto the brain; it lies in the anterior part of the pleuroperitoneal cavity,attached to the under side of the alimentary tube, and in a position justabove the letters pp in Fig. 40. Immediately in front of it is theuncleft mesoblast of the neck, which, as has already been stated, nevercleaves into somatic and splanchnopleuric layers. Soon after the first appearance of the primary cardiac cavities thecells immediately surrounding them (Fig. 106) form a special layer,which is the beginning of the endothelium of the heart. Cells exter- DEVELOPMENT OF ORGANS AND SYSTEMS. 171 nal to this also differentiate and multiply (Figs. 106, 107, 108); theyultimately form the myocardium. A space exists for some time (, 107) between th
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectobstetrics, bookyear1
