The elements of embryology (1874) The elements of embryology elementsofembryo01fost Year: 1874 188 THE FIFTH DAY. [CHAP. Fig. 59. lew aqc ctcw Section through the Spinal Cord op a Seven Days' Chick. w. posterior white column. I. c. w. lateral white column, a. c. w. anterior white column, p c. posterior cornu, of grey matter, consisting of very small cells, a. c. anterior cornu of grey matter, with a peculiar mass of very large cells, ep. epithelium lining the original medullary canal, pos- terior fissure. The posterior fissure is chiefly formed by the upper portion of the origina
The elements of embryology (1874) The elements of embryology elementsofembryo01fost Year: 1874 188 THE FIFTH DAY. [CHAP. Fig. 59. lew aqc ctcw Section through the Spinal Cord op a Seven Days' Chick. w. posterior white column. I. c. w. lateral white column, a. c. w. anterior white column, p c. posterior cornu, of grey matter, consisting of very small cells, a. c. anterior cornu of grey matter, with a peculiar mass of very large cells, ep. epithelium lining the original medullary canal, pos- terior fissure. The posterior fissure is chiefly formed by the upper portion of the original medullary canal which becomes open above. The upper portion of it is now filled with tissue (c) which is probably derived from the epithelium of the medullary canal. The lower portion of the medullary canal becomes the spinal canal (sp. c.) and is eventually entirely shut off from posterior fissuz-e. The communication between the spinal canal and the posterior fissure is already narrowed, and if the section had been made further forwards, the two would have been entirely separated from each other. a. f. anterior fissure. This is formed in an entirely different manner from the posterior fissure. It is produced by the anterior column of white, and the anterior cornu of grey matter, growing downwards and leaving between them a fissure. It is at this time filled up with connective tissue. a. g. c. anterior grey commissure, c. tissue filling up the end of the posterior fissure, sp. c. spinal canal. Only the right half of the cord is represented in the figure. The section passes through the cord between the entrance of two spinal nerves. The angular form of the cells of the cord has not been done justice to by the engraver.
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