The anatomy of the nervous system, from the standpoint of development and function . um is characterized by the presence of a thicklayer of myelinated fibers upon its surface. The hippocampus, which constitutes an olfactory center of a still higherorder, is directly continuous with the portion of the hippocampal gyrus knownas the subiculum (Fig. 209), and is formed by a primitive portion of the cortex 278 THE NERVOUS SYSTEM that has been rolled into the ventricle along the line of the hippocampal its ventricular surface it is covered by a thin layer of white matter, knownas the al
The anatomy of the nervous system, from the standpoint of development and function . um is characterized by the presence of a thicklayer of myelinated fibers upon its surface. The hippocampus, which constitutes an olfactory center of a still higherorder, is directly continuous with the portion of the hippocampal gyrus knownas the subiculum (Fig. 209), and is formed by a primitive portion of the cortex 278 THE NERVOUS SYSTEM that has been rolled into the ventricle along the line of the hippocampal its ventricular surface it is covered by a thin layer of white matter, knownas the alveus, through which the fibers arising in the hippocampus reach thefimbria and the fornix. Beginning at the line of separation from the fasciadentata, we may enumerate the constituent layers of the hippocampus as fol-lows: the molecular layer, the layer of pyramidal cells, and the layer of poly-morphic cells (Figs. 209, 210). The molecular layer contains a superficial stratum of tangential fibers derivedfrom the corresponding layer of the subiculum and from bundles of fibers that. Fig. 209.—Cross-section of the hippocampus and hippocampal gyrus of man. (Edinger.) perforate the cortex of the subiculum (Fig. 210). More deeply placed is anotherfiber layer, containing collaterals from the pyramidal cells as well as collateral andterminal fibers from the alveus, and known as the stratum lacunosum. Themolecular stratum in the hippocampus resembles that in other parts of the cortexin containing the terminal branches of the apical dendrites from the pyramidalcells, and a few nerve-cells which for the most part belong to Golgis Type Layer of Pyramidal Cells.—The pyramidal cells are all of medium sizeand their fusiform bodies are rather closely packed together, forming a well- THE 79 defined zone, the stratum lucidum. Their apical dendrites are dire* led towardthe molecular layer and form the chief constituent of the stratum axons of these cells,
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