. The development of the human body : a manual of human embryology. Embryology; Embryo, Non-Mammalian. FORMATION OF THE GERM LAYERS 51 blastoderm, the cells of which, in front of the groove, arrange them- selves in a superficial layer one cell thick, which may be regarded as the ectoderm (Fig. 27, ec), and a subjacent mass of somewhat scattered cells. Later the lowermost cells of this subjacent mass arrange themselves in a continuous layer, constituting what is termed the primary endoderm (en1), while the remaining cells, aggregated. prm ... Fig. 27.âLongitudinal Sections through Blastoderms o
. The development of the human body : a manual of human embryology. Embryology; Embryo, Non-Mammalian. FORMATION OF THE GERM LAYERS 51 blastoderm, the cells of which, in front of the groove, arrange them- selves in a superficial layer one cell thick, which may be regarded as the ectoderm (Fig. 27, ec), and a subjacent mass of somewhat scattered cells. Later the lowermost cells of this subjacent mass arrange themselves in a continuous layer, constituting what is termed the primary endoderm (en1), while the remaining cells, aggregated. prm ... Fig. 27.âLongitudinal Sections through Blastoderms of the Gecko, showing â Gastrulation. ec, Ectoderm; en, secondary endoderm; en', primary endoderm; prm, prostomial meso- derm.â (Will.) especially in the region of the crescentic groove, form the prostomial mesoderm (prm). In the region enclosed by the groove a distinct delimitation of the various layers does not occur, and this region forms the primitive streak. The groove now begins to deepen, forming an invagination of secondary endoderm, the extent of this invagination being, however, very different in different species. In the gecko (Will) it pushes forward between the ectoderm and primary endoderm almost to the anterior edge of the blastoderm (Fig. 27, B), but later the cells forming its floor, together with those. 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 McMurrich, J. Playfair (James Playfair), 1859-1939. Philadelphia : P. Blakiston's son & co.
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Keywords: ., bookautho, bookcentury1900, bookdecade1910, booksubjectembryology
