The nuclei tuberis laterales and the so-called ganglion opticum basale.

  • Malone, Edward F.
Date:
1914
Catalogue details

Licence: In copyright

Credit: The nuclei tuberis laterales and the so-called ganglion opticum basale. Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

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    teristic cell type. A reference to Fig. 36 will serve as an introduction to the further consideration of the differences in cell character. On comparing the cell character of the nuclei tuberis laterales of man and macacus (Figs. 39 and 45) with that of the other cell groups shown in the illustrations it will at once be evident that this cell type differs radically from all others except that of the substantia grisea of the third ventricle (Figs. 40 and 46) ; this similarity is of importance, and its significance will be considered when the relationship of the various cell types is discussed. Comparing the cell type of the nuclei tuberis laterales in man (Fig. 39) and in macacus (Fig. 45) it is evident that aside from the presence of pigmentation in man (of course not to be expected in macacus) there is no essential difference. The fundamental characteristic of this cell type in both forms lies in the appearance of the cytoplasm, which contains an extremely small amount of Nissl substance in the form of fine granules; the relation of cell nucleus to cytoplasm in respect to volume is <also practically the same, although in macacus the cytoplasm is relatively less, a change that is to be expected, as will appear later. In describing the cells of the nucleus ansae peduncularis (p. 18) I pointed out the fact that if two cell groups differ as to the amount of yellow pigment in their cells they will also differ in other respects, and that homologous groups in lower animals (where all pigmentation is absent) will also appear different. Accordingly the presence of densely packed yellow granules in the cells of the nuclei tuberis laterales of man is not the only distinctive charac- teristic of these cells, but is connected with other characteristics, common also to the homologous cells of macacus; these characteristics involve the appearance of the cytoplasm and make it possible to separate these cells without difficulty from those of surrounding groups. If we study the cell type of the substantia grisea in all four forms (Figs, 40, 46, 51, and 56) we find the cell type practically unchanged, since in all forms the cells of this group are characterized by the extremely small amount of cytoplasm and relatively large nucleus; in many cells the cytoplasm is almost absent, and one sees only a large nucleus and perhaps one or more cell processes. Accordingly the cells of the substantia grisea may be readily separated from those of all portions of the nuclei tuberis laterales not only through their smaller size, but also through the minute amount of cytoplasm in relation to the size of the cell nucleus; however, on the border line between these two types of cells occur occasionally transi-