Tetrodotoxin secreting glands in the skin of puffer fishes.

Unique exocrine glands or gland-like structures were found in the skin of several species of puffer fishes of the genus Takifugu. The glands of T. pardalis and T. vermiculare porphyreum consisted only of secretory cells with a large vacuole. These cells were completely enclosed by epithelial cells with developed microfilaments, except at their opening to the lumen. The contents of the large vacuole in the peculiar secretory cell were forced out when the puffer was stimulated. Exocrine glands or gland-like structures with peculiar secretory cells were also found in the skin of T. poecilonotus, T. niphobles and T. vermiculare radiatum. A high concentration of TTX was detected in the gland contents collected directly from live specimens of T. pardalis. We therefore conclude that these glands are TTX secreting glands.