This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1902 Excerpt: ...the fifth cleavage; it commonly divides about the time that the blastoderm cells prepare for the next (sixth) cleavage; but at times the cleavage of the entoblast is so delayed as to be nearly simultaneous with the sixth cleavage of the blastoderm cells. The nuclear spindle is usually almost perpendicular to the ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1902 Excerpt: ...the fifth cleavage; it commonly divides about the time that the blastoderm cells prepare for the next (sixth) cleavage; but at times the cleavage of the entoblast is so delayed as to be nearly simultaneous with the sixth cleavage of the blastoderm cells. The nuclear spindle is usually almost perpendicular to the sagittal plane (Figs. 52, 116, 117). A cleavage plane, dividing the yolk nearly equally makes its appearance at this stage, but it becomes more clearly visible about the time that the next division takes place in the blastoderm cells, and it may therefore be described later, in connection with the figures which illustrate the account of the sixth cleavage. The blastoderm has been greatly extended since the last stage, owing to the multiplication of its cells by division, and to the accompanying increase of surface produced by the flattening of the cells. The blastopore has become less extensive as the yolk-cell (entoblast) has become more completely covered (Plate 6, Figs. 51, 54; Plate 8, Fig. 69). It is filled by the protoplasmic portion of the yolk-entoblast, and is bounded posteriorly by the two primary mesoblast cells (rf6-8, i6-4), anteriorly and laterally by the four mes-ectoblast cells (a8-8, 66-8, J6-4, c6-8). With the exception of these four cells, which are in contact with the yolkentoblast at the blastopore, all other cells of the blastoderm are purely ectoblastic. Figures 47-55 (Plate 6), 69, 70 (Plate 8), and 114-117 (Plate 12), show the details of cell arrangement in the thirty-two-cell stage. There is slight variability in the adjustment of the cells to one another, but examination of the figures shows that the relative positions of the cells are the same in all cases. In good transparent preparations I have seen hundreds of eggs in ...
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Add this copy of The Early Development of Lepas. a Study of Cell-Lineage to cart. $54.95, good condition, Sold by Bonita rated 4.0 out of 5 stars, ships from Hialeah, FL, UNITED STATES, published 2019 by Wentworth Press.
