CYTOLOGICAL STUDIES ON MUCUS FORMATION AND SECRETION IN BUSYCON

¹ Dept. of Biological Sciences, University of Delaware, Newark, Delaware, and Marine Biological Laboratory, Woods Hole, Mass.

1. The hypobranchial (mucous) gland of Busycon canaliculatum (L.) is located in the pallial cavity. It contains ciliated cells and three types of mucous cells.

2. Mucous cells of type 1 are thought to be precursors of type 2 because of the relative sizes and positions of the two types of cells, and because mucous vacuoles of type-1 cells appear to have varying degrees of resemblance to those of type-2 cells. Evidence concerning the relationships of type-3 cells is lacking.

3. The commonest type of mucous cell (type 2) is long and slender with a bulbous tip, one or two swellings along its length, and a basal nucleus. Most of the cell is occupied by a mucous vacuole, whose contents stain metachromatically (reddish violet) with toluidine blue O, red with mucicarmine, blue-green with alcian blue 8GS, and are partly digested by hyaluronidase. The surrounding cytoplasm contains yellow pigment granules, mitochondria, Golgi apparatus, and nadi-positive granules. The distribution of sudanophilic material is peculiar in that a belt of lipid granules surrounds the sub-distal portion of the bulbous tip of the vacuole. No glycogen could be demonstrated in these cells.

4. It is possible that the activities of mucous cells require diffusion of carbohydrate materials from adjacent cells. The results of the cytochemical tests suggest that aerobic utilization of carbohydrates (possibly galactose) or lipid materials, and the binding of sulfate groups may be of importance in the formation of mucus from its precursors.