. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. URN CELL MUCUS 573 '. R FIGURE 1. Profile of unstained urn cell complex: vesicle cell (v), base cell (b), and R cells (R) covered by adherent amebocytes. Cilia do not show. (about 2 /AMI) secretory cells attached to the external membrane of the base cell (Fig. 2). The vesicle cell is very thinly stretched to form a transparent hollow dome (Fig. 3, inset), the base of which is attached to the upper rim of a quadrifoil saucer-shaped mucociliated base cell by junctional complexes. The two cells thus enclose a transparent matrix
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. URN CELL MUCUS 573 '. R FIGURE 1. Profile of unstained urn cell complex: vesicle cell (v), base cell (b), and R cells (R) covered by adherent amebocytes. Cilia do not show. (about 2 /AMI) secretory cells attached to the external membrane of the base cell (Fig. 2). The vesicle cell is very thinly stretched to form a transparent hollow dome (Fig. 3, inset), the base of which is attached to the upper rim of a quadrifoil saucer-shaped mucociliated base cell by junctional complexes. The two cells thus enclose a transparent matrix. Attached to the center of the outer membrane of the base cell, also by junctional complexes, is the cluster of small secretory R cells (so designated in honor of Reissig). Between the R cells and the mucociliated rim of the base cell are several (usually four) loci of synthesis of free-flowing mucus secreted in response to defined stimuli. The static and active relationships are diagramed in Figures 2 and 3. There is an apparent division of labor between the two secretory systems: the R cells continually and slowly produce brief tails of granular mucus that is selectively sticky for cell debris and foreign participates; the other system is at rest until the loci on the nonciliated portion of the base cell membrane are stimulated to secrete streamers of free-flowing mucus. Evidence for tivo separate secretory systems The R cells. If a drop of fresh whole blood from S. nudns is diluted about 1:20 in seawater and put on a glass slide, it can be seen that the rapidly swimming urn- cell complexes have few, if any, autologous cells adherent to them. However, in fresh preparations of supernatant urn cell complexes, the R cells nearly always have moderate loads of adherent amebocytes (Fig. 1), presumably activated as a. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illust
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
