Defense Date


Document Type


Degree Name

Master of Science


Anatomy & Neurobiology

First Advisor

Richard J. Krieg, Jr.


The tau mutation affects the circadian system of the golden hamster primarily by decreasing the period of the activity cycle from 24 to 20 hours. To study the effect of this mutation on reproductive function in the golden hamster, 3 experiments have been designed. In the first experiment, wild-type and tau female hamsters will be maintained in conditions of 14:10 LD and 11.7:8.3 LD, respectively. Blood samples will be taken and analyzed by radioimmunoassay (RIA) to determine the timing of the proestrus LH surge. In the second experiment, wild-type and tau males will be transferred to shortened photoperiods of 10:14 LD and 8.3:11.7 LD, respectively, and testicular length and width will be used as a measure of the onset of testicular regression and subsequent recrudescence. In the final experiment, wild-type and tau females will be transferred to conditions of 10:14 LD and 8.3:11.7 LD, respectively, and the time to the onset of anestrus will be recorded. It is expected that in the tau females, the preovulatory LH surge will occur 8.4 hours after lights-on. The onset of gonadal regression, recrudescence, and anestrus will occur 16.7% [(24 hours - 20 hours)/24 hours] sooner in the mutant hamster when measured in absolute time. When the time to the onset of these processes is measured in light cycles, however, it is probable that these events occur within the same number of light cycles in both the wild-types and the tau hamsters. The basic hypothesis is that the main impact of the tau mutation will be on the timing of these specific reproductive phenomena, but the fundamental physiological characteristics of these events will remain unaffected. These results would suggest that the timing of the preovulatory LH surge and the occurrence of gonadal regression, recrudescence, and anestrus in a shortened photoperiod are driven by the same neural oscillator that regulates the period of the activity cycle in the golden hamster.


Scanned, with permission from the author, from the original print version, which resides in University Archives.


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