Date of Award


Document Type


Degree Name

Master of Science (M.S.)


Biological Sciences

First Advisor

Eric O. Thomas

First Committee Member

Paul A. Richmond

Second Committee Member

James W. Blankenship


Many studies have been done on the neural control of serous gland secretion in the skin of frogs and newts. However, no studies have been published on the effects of adrenergic and cholinergic neurotransmitters on the sexually dimorphic breeding glands of male frogs. The present study examined the effects of neurotransmitters on the serous and breeding glands of Hymenochirus curtipes. Explants of dorsal skin and postaxial skin (containing whole breeding glands) were incubated in vitro with epinephrine, norepinephrine or acetylcholine for 30 minutes. The explants were then preserved and examined histologically for signs of secretion. The area and perimeter of the serous and breeding glands were measured before (control groups) and after the treatments. Epinephrine and norepinephrine treatments decreased the overall area of the serous gland. However, acetylcholine had no effect on serous gland size. The effect of epinephrine on serous gland area was partially blocked by the adrenergic antagonist phenoxybenzamine. Measurement of individual lobes and whole breeding glands after 30 minutes of treatment (with epinephrine, norepinephrine, and acetylcholine) showed no significant change in area or perimeter. This experiment confirmed earlier studies demonstrating that adrenergic and not cholinergic stimulation can affect the secretion of serous glands in frogs. However, specific antagonists can mask these effects. In contrast, breeding gland secretion showed no variation in overall area or individual lobe size. Thus, breeding gland secretion is not regulated by adrenergic or cholinergic systems.



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