Fine structure of the venom gland epithelium of the south american rattlesnake and radioautographic studies of protein formation by the secretory cells

Abstract

Ribeiriio P d t o , S.P., B r a d ABSTRACTThe South American rattlesnake venom gland is made up of secretory tubules lined by a simple columnar epithelium containing horizontal cells, mitochondria-rich cells, and the principal cell type, the columnar secretory cells. This cell has a round basal nucleus and abundant rough endoplasmic reticulum, the cisternae of which are variably distended with flocculent material containing many dense intracisternal granules. The supranuclear Golgi apparatus is spherical, with stacks of flattened saccules at the periphery and large vacuoles containing masses of dense material, and other dense granules in the center. Similar but smaller granules are present at the apex where they fuse with the microvillus-covered apical membrane and release their content into the lumen. Protein synthesis was studied in snakes injected with 3H-tyrosine and sacrificed at several times after injection. Radioautographs showed reactions at one half and one hour over the ribosomes and membranes of the rough endoplasmic reticulum. At two hours the immature face of the Golgi apparatus was labeled. At four hours Golgi saccules and vacuoles with dense masses (secretory granules) were labeled, and at eight hours the dense masses within the secretory granules were heavily labeled both in the Golgi region and in the apex near the lumen. Labeled material was found in the lumen at two days. Intracisternal granules were first labeled at eight hours, and by two days reactions remained only over the flocculent content and intracisternal granules of the rough endoplasmic reticulum. Thus, venom protein was synthesized on the rough endoplasmic reticulum, migrated through the Golgi apparatus and accumulated in the dense masses of the secretory granules, which moved to the apex and were extruded. The labeling of intracisternal granules at eight hours and two days after injection indicated a storage nature for these granules.The venom glands of snakes are modified salivary glands with several cell types in their secretory epithelium (Kochva and Gans, '64, '65, '66, '70; Odor and Gennaro, '60; Odor, '65). With the exception of the work of Odor ('65), and more recently of Kochva and Gans ('70) and , no systematic study of the fine structure of the venom glands was found. Also, no dynamic studies, using radioactive precursors and electron microscopic radioautography have followed the cellular events involved in venom synthesis and secretion.Most radioautographic work on protein formation has been done on small mammals such as rats and mice (Leblond, '65) because of their availability and ease of handling. Despite this, many other organisms have systems which lend themselves much better to studies of protein synthesis. Among these systems are the exocrine venom glands of poisonous snakes. These glands produce large quantities of proteins, some of which have been well characterized and shown to possess the harmful enzymatic or neurotoxic properties of the venom (Gosh and Sarkar, '56). In addi- WARSHAWSKY, HADDAD, GONCALVES,...

Unusual aspects of the venom apparatus of the blue coral snake, Maticora bivirgata.

“…The large vacuoles or some vacuoles or cavities with dense intracavity material may contain the venom secretion; this has been supported in C. d. terrificus by radioautographic studies (WARSHAWSKY et al, 1973). Horizontal cells or basal cells have been described by GANS (1965), ODOR (1965), WARSHAWSKY et al, 1973, GOPALAKRISHNAKONE, 1985a, 1986 in various snake venom glands. There has been discussion by these authors on the functions of these cells as to whether they are myoepithelial cells or embryonic cells with the potential to differentiate into secretory cells.…”

“…However, WARSHAWSKY et al (1973) mentions an infrequent type of "dark cell" among the columnar secretory cells of the South American rattlesnake. The lack of a large amount of secretory granules such as the zymogen granules in the cytoplasm of the secretory cell-is a subject of much debate (ODOR, 1965;GENNARO et al, 1960GENNARO et al, ,1963WARSHAWSKY et al, 1973). The large vacuoles or some vacuoles or cavities with dense intracavity material may contain the venom secretion; this has been supported in C. d. terrificus by radioautographic studies (WARSHAWSKY et al, 1973).…”

“…In previous studies of different species, such as the South American rattlesnake Crotalus durissus terrificus, three cell types were established: the horizontal cell, mitochondria-rich cell and columnar secretory cell (WARSHAWSKY et al, 1973). In the cottonmouth moccasin Ancistrodon p. piscivorus, there were five types of cells: the principal cell, the horizontal cell, mitochondria-rich cell and two lesser common types (ODOR, 1965).…”

“…The lack of a large amount of secretory granules such as the zymogen granules in the cytoplasm of the secretory cell-is a subject of much debate (ODOR, 1965;GENNARO et al, 1960GENNARO et al, ,1963WARSHAWSKY et al, 1973). The large vacuoles or some vacuoles or cavities with dense intracavity material may contain the venom secretion; this has been supported in C. d. terrificus by radioautographic studies (WARSHAWSKY et al, 1973). Horizontal cells or basal cells have been described by GANS (1965), ODOR (1965), WARSHAWSKY et al, 1973, GOPALAKRISHNAKONE, 1985a, 1986 in various snake venom glands.…”

Fine structure of duvernoy's gland of the japanese colubrid snake, Rhabdophis tigrinus.

“…x 24,000 which the cells from the salivary gland have been extensively studied both structurally and functionally (YOUNG and VAN LENNEP, 1978;GARRETT and EMMELIN, 1979). The secretory units of Duvernoy's gland in colubrid snakes and of the venom gland in viperid snakes contain flattened cells, called basal or horizontal cells, which are interposed between the basement membrane and the basal part of the secretory cells (GYGAX, 1971;WARSHAWSKY et al, 1973). The horizontal cells of the South American rattlesnake, Fig.…”