The poison gland of the cottonmouth moccasin, Ancistrodon P. piscivorus, as observed with the electron microscope

The structure of the poison gland of the cottonmouth moccasin has been studied with the electron microscope. This gland is divided functionally and structurally into a posterior and an anterior portion. In the posterior gland the columnar principal cells are considered to be responsible for the production of the secretory material, including the toxic substances in the venom. This cell is characterized by numerous dilated membrane pairs of the granular endoplasmic reticulum and by a large Golgi complex. Four other types of cells are observed within the epithelial layer of the posterior part of the gland, but their function is unknown. The majority of the cells of the anterior part of the gland are mucous‐secreting goblet cells. Some possible stages in their secretory cycle are described. Granular endoplasmic reticulum is present in the basal areas of the cell. The accumulation of recognizable secretory material appears first in structures considered to be a part of the Golgi complex.