. The development of the chick : an introduction to embryology. Embryology; Chickens -- Embryos. 258 THE DEVELOPMENT OF THE CHICK In the course of the fourth and fifth days aggregations of sympathetic ganghon cells begin to appear ventral to the aorta, and in the mesentery near the intestine. The connection of these with the primary cord is usually rendered evident by agreement in structure, and by the presence of intervening strands of cells; moreover, in point of time they always succeed the primary cord, so that their origin from it can hardly be doubted. About the sixth day the secondary o
. The development of the chick : an introduction to embryology. Embryology; Chickens -- Embryos. 258 THE DEVELOPMENT OF THE CHICK In the course of the fourth and fifth days aggregations of sympathetic ganghon cells begin to appear ventral to the aorta, and in the mesentery near the intestine. The connection of these with the primary cord is usually rendered evident by agreement in structure, and by the presence of intervening strands of cells; moreover, in point of time they always succeed the primary cord, so that their origin from it can hardly be doubted. About the sixth day the secondary or permanent sympathetic trunk begins to appear as a series of groups of neuroblasts situ- ated just median to the ventral roots of the spinal nerves. They. l^efiAS. Fig. 152.— Reconstruction in the sagittal plane of the anterior spinal and sympathetic gan- glia of a chick embryo of 4 days. (After Neumayer.) Ceph. S., Cephalic continuation of the sym- pathetic trunk. S. C, Sympathetic cord. Sg., Sympathetic ganglion, sp., Spinal nerve, spg., Spinal ganglion. R. C, Ramus communicans. are thus separated from the spinal ganglia only by the fibers of the ventral roots between which neuroblasts may be found, caught apparently in migration from the spinal to the sympa- thetic ganglion. The number of these secondary sympathetic ganglia is originally 30, one opposite the main vagus ganglion, and each spinal ganglion to the twenty-ninth (Fig. 150). Soon after their origin they acquire three connections by means of axones, viz., (a) central, with the corresponding spinal nerve-. 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 Lillie, Frank Rattray, 1870-1947. New York : Henry Holt
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Keywords: ., bookauthorlilliefrankrat, bookcentury1900, booksubjectembryology
