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Date of Award

1998

Document Type

Thesis - Pacific Access Restricted

Degree Name

Master of Science (M.S.)

Department

Biological Sciences

First Advisor

Eric Thomas

First Committee Member

Lee Christianson

Second Committee Member

Alice S. Hunter

Third Committee Member

John Livesey

Abstract

Ovulation due to hypothetical conspecific male pheromone(s) was examined in the dwarf African clawed frog (Hymenochirus curtipes, Noble, 1924). Oviducts of females were examined for the presence of eggs in untreated females and after exposure to each variable condition. A flow-through water system was constructed, and a total of nine experimental runs performed. Mature, female H. curtipes were exposed to seven different water conditions to discern which stimuli induced ovulation. One ovulation stimulus may be a male pheromone; the cutaneous post-axillary gland of male H. curtipes and the testes have also been suggested as possible organs of pheromone secretion. Therefore, females were exposed to post-axillary gland and testicular homogenates. Females were also exposed to other variable conditions, including plain flowing water, gonadotropin releasing hormone agonist (GnRH-a) in water, and GnRH-a injected males. Ovulation was induced in females exposed to two of the variable conditions: GnRH-a injected males (87%) and uninjected-glandless males (85%). No other treatments induced ovulation at these levels, although GnRH-a in water induced ovulation in females (70%). From the results obtained, it can be concluded that male H. curtipes secrete chemical(s) which stimulate(s) females, though the source and nature of the pheromone has not been identified. While GnRH-a in water can induce ovulation in females, it is not as effective as the pheromone(s) released by male H. curtipes.

Pages

65

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