. Journal of morphology. erved in meroblastic eggs. Stage 12: {figs. 138 to 150 and 223 to 225). This stage is char-acterized by the presence of the neural groove and is terminatedby the appearance of the neural folds. The neural groove appearsabout three days after the beginning of gastrulation. At the time of the earliest indications of the neural groove,the blastopore has just become a complete circle. At the closeof the preceding stage it had a diameter of about 94 degrees;it now rapidly becomes smaller, so that before the appearanceof the neural folds its diameter averages about 26 degree
. Journal of morphology. erved in meroblastic eggs. Stage 12: {figs. 138 to 150 and 223 to 225). This stage is char-acterized by the presence of the neural groove and is terminatedby the appearance of the neural folds. The neural groove appearsabout three days after the beginning of gastrulation. At the time of the earliest indications of the neural groove,the blastopore has just become a complete circle. At the closeof the preceding stage it had a diameter of about 94 degrees;it now rapidly becomes smaller, so that before the appearanceof the neural folds its diameter averages about 26 degrees ( to 145). During the early part of this stage the yolk plug is characterizedby a broad crescent-shaped or horseshoe-shaped area of smallercells lying ventrad and laterad to the macromeres (figs. 138 and139). Along the lateral line of transition between the macromeresand these smaller cells, the cells appear compressed and exhibita tendency to line up and merge their cleavage furrows (figs. 498 BERTRAM G. SMITH.
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Keywords: ., bookcentury1900, bookdecade1, booksubjectphysiology, bookyear1912
