. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. At the end of the gland they are succeeded suddenly by the zymogenic cells. In these the minute structure is obscured by the large amount of prozymogen present. The cells are less flattened than at the earlier stage of development, probably because the initial distention has been compensated by the rapid division and growth of the cells. A number of these cells is represented in Fig. 6, B. They are now somewhat columnar in shape, with convex ends projecting into the lumen. The nucleus is round or oval and placed in the cente
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. At the end of the gland they are succeeded suddenly by the zymogenic cells. In these the minute structure is obscured by the large amount of prozymogen present. The cells are less flattened than at the earlier stage of development, probably because the initial distention has been compensated by the rapid division and growth of the cells. A number of these cells is represented in Fig. 6, B. They are now somewhat columnar in shape, with convex ends projecting into the lumen. The nucleus is round or oval and placed in the center of the cell, though in the more columnar cell it is often nearer the lumen than the base of the cell. The free end of the cell may be seen in sections stained with neutral gentian, to be filled with granules of zymogen. Other granules may be seen at the sides of the nucleus, and a few are occasionally found in the base of the cell. The rest of the cell is oc- cupied by a deeply staining protoplasm, which owes its ability to absorb nuclear stains to the large amount of prozymo- gen present, as may be shown by the employment of Macallum's methods of detecting masked iron. The distribution of the prozymogen determines the appearance of the cell, and three main types are to be recognized ; in the first the stain is diffused through the whole of the protoplasm, but more pronounced at the base and sides of the cell, and on close examination a very finely vacuolated structure may be made out ; in the second the whole or part of the cell exhibits long deeply stain- ing fibrillae ; and in the third type the prozymogen is distrib- uted as small irregularly staining particles throughout the protoplasm. All the three main types of cells composing the glands and surface epithelium are still capable of division, and numerous mitoses may be seen in all. Oppel's description of the structure of the oesophageal glands of Proteus would apply word for word to these glands FIG. 6. — Oesophageal
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
