Seasonal Changes in the Gonads and Accessory Reproductive Organs of the Wild Male Rat (Rattus Norvegicus)
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Authors
Lorincz, Margaret Alice
Issue Date
1971
Volume
Issue
Type
Thesis
Language
en_US
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Abstract
Seasonal breeders, influenced by such factors as photoperiod, temperature, and population size, reproduce during a certain time of year thus ensuring that young are born at a most favorable time (Amoroso and Matthews, 1955). During the breeding season of an adult male, sperm cells are formed in the seminiferous tubules and are found in abundance. Leydig cells (interstitial testosterone-producing cells) are large, containing large oval nuclei; the accessory reproductive organs, at this time, are filled with fluid. After an active breeding season, however, spermatogenesis ceases and the gonads and accessory organs regress. Within the seminiferous tubules there is a sloughing of the epithelium to a point where only primitive cell types are found, the lumina become clogged with cellular debris, and the Leydig cells appear inactive and contain little cytoplasm. Regressed accessory organs show a marked decrease in epithelial cell height. The reproductive organs of the continuous breeder, on the other hand, remain reproductively active throughout the year and breeding can occur at any time (Albert, 1961). Examples of seasonal breeding patterns which are seen in several adult male mammals are cited below.
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Publisher
Creighton University
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