. Cytology, with special reference to the metazoan nucleus. Cells. 130 CYTOLOGY CHAP. vesicles, then the walls of these vesicles break down to produce a common nuclear cavity, in which, however, the regions of the vesicles can still be recognized by the slightly denser core of chromatin occupying what was formerly their axes. In prophase the chromosomes condense again in the limits of these vesicles (Fig. 60, A-E). In Locusta viridissima (Otte, 1907) the chromosomes of the spermato-. Fig. 60. Formation of chromosome vesicles in the spermatogonia of Orthoptera. (A-E, Phrynotettix tnagnus, after
. Cytology, with special reference to the metazoan nucleus. Cells. 130 CYTOLOGY CHAP. vesicles, then the walls of these vesicles break down to produce a common nuclear cavity, in which, however, the regions of the vesicles can still be recognized by the slightly denser core of chromatin occupying what was formerly their axes. In prophase the chromosomes condense again in the limits of these vesicles (Fig. 60, A-E). In Locusta viridissima (Otte, 1907) the chromosomes of the spermato-. Fig. 60. Formation of chromosome vesicles in the spermatogonia of Orthoptera. (A-E, Phrynotettix tnagnus, after Wenrich, , 1916; F, Brachystola magna, after Sutton, , 1903 ; G, H, I, Locusta viridissima, after Otte, , 1907). A, B, C, successive stages in the formation of the resting nucleus out of the telo- phase chromosomes; D, E, prophase; F, early prophase; G, telophase; H, resting "nucleus " ; I, prophase. gonial telophases do not come into contact at all, but each one forms a separate little nucleus, or karyomere, by itself (Fig. 60, G-I.) No common nuclear membrane is formed to enclose them, but they remain separate from one another, with cytoplasm extending in between them. This account refers to the earlier spermatogonial divisions. In the last one before the meiotic phase a compound nucleus is formed in the usual way. Karyomere formation— the formation of a separate little nucleus. 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 Agar, W. E. (Wilfred Eade), 1882-1951. London, Macmillan and Co. , limited
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectcells, bookyear1920
