One hundred ten larvae of Amblystoma tigrinum melanosticum were used to determine the approximate stage at which time the skin glands of the tiger salamander start secreting. It was determined that the serous glands (poison-venom) do not secrete upon stimulation either naturally or artificially until the animals are in the very last stages of metamorphosis. Shortly after metamorphosis there is a profuse secretion of the poison glands as well as some increase of mucous secretion upon stimulation. The poison glands are chiefly located in the dorsal two thirds of the body skin whereas the mucous glands are on the ventral one third. The chief stimulus was an electrical shock of three volts, with a frequency pulse of twenty per second, a duration of ten milliseconds. Poison glands are more effective on the predator in those animals that are non-aquatic. This is nature's way of protecting the metamorphosed tiger salamander. The poison glands are three times the size of a mucous gland; each possesses a blood capillary ring (net). Project Number 116.
Roofe, Paul B.
"Ontogenesis of Secretion in the Skin of the Tiger Salamander,"
Jackson Hole Research Station Annual Report: Vol. 1962
, Article 15.
Available at: http://repository.uwyo.edu/jhrs_reports/vol1962/iss1/15