The American journal of anatomy . agittal section. Hsenialum. the distinction between the neural plate and hypophysis at oncebecomes clearly marked (Figs. 2 and 3). From the earliest stagethe hypophysis rests against the tip of the preoral entoderm. While the neural tube is rolling up, the hypophysial ectoderm be-comes deeper, so that in sagittal section the depth of the trianglebecomes greater than the length of its base on the surface (Fig. 3).Up to this time the cells within the triangle show no regularity ofarrangement. Immediately following this it is seen that the deepercells are arrange
The American journal of anatomy . agittal section. Hsenialum. the distinction between the neural plate and hypophysis at oncebecomes clearly marked (Figs. 2 and 3). From the earliest stagethe hypophysis rests against the tip of the preoral entoderm. While the neural tube is rolling up, the hypophysial ectoderm be-comes deeper, so that in sagittal section the depth of the trianglebecomes greater than the length of its base on the surface (Fig. 3).Up to this time the cells within the triangle show no regularity ofarrangement. Immediately following this it is seen that the deepercells are arranged so as to suggest a short blind sac. From the start(Fig. 5) this sac is thicker on the anterior or dorsal side. It has The Limit Between Ectoderm and Entoderm. 49 no actual cavity, bnt the arrangement and pigmentation of the cellssuggest a cavity, and the wall next to the entoderm is thin and devoidof nuclei. By this time the ectoderm of the mouth plate, caudal tothe hypophysis, consists of only a single layer of flat cells (see. a Fig. G.
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectanatomy, bookyear1910
