SECRETORY VESICLE REFILLING AND TOXIN PRODUCTION IN OLLOTIS NEBULIFER (COASTAL PLAIN TOAD) AND ANAXYRUS SPECIOSUS (TEXAS TOAD) FOLLOWING TRANSCUTANEOUS ELECTRICAL STIMULATION OF THE PAROTOID GLANDS

摘要

Parotoid glands in two species of toads, Ollotis nebulifer and Anaxyrus speciosus were expressed using transcutaneous electrical stimulation. Toads were euthanized at various time stages following gland expression. Of the toads that had parotoid glands expressed, microscopic examination revealed the majority of the vesicles in the glands had emptied significantly with little to no contents remaining. General morphology of the vesicles was similar in both species with vesicles in A. speciosus somewhat smaller and more numerous than in O. nebulifer. Unexpressed vesicles were generally ovoid in shape with smooth cell walls. Emptied vesicles displayed numerous invaginations of the cell wall, resulting in the decrease of the vesicle volume. No gross injury or damage to the emptied vesicles or surrounding structures was noted. Hypertrophy of the inner (secretory) cell wall layer was evident at 24 h in both species. The majority of vesicles in both species had completely refilled and resumed normal size and shape within 5 to 7 days following gland expression.