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  • Author: P. H. Krutzsch x
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P. H. Krutzsch

Summary. Knowledge relative to the reproduction of nonhibernating bats is reviewed. Events in the male, as they are now understood, are summarized for all families for which data exist. Attention is given to the wide species diversity of male accessory sex organs in respect to gross structure and glandular complement. Stability or variability of organization of the male reproductive system is noted. Functional relationships between primary and accessory sex organs are considered and any synchrony between these organs and their functional cyclicity identified.

Various frequencies of male reproductive cycles are examined for each species within families. Factors influencing male reproductive events in nonhibernating Chiroptera are briefly considered. It has long been speculation that reproductive cycles under natural conditions are strikingly related to the environment, with such features as temperature, moisture, length of day and available food all implicated. These cues, however, appear to be filtered through varied genetic potential and physiological patterns, since not all species respond similarly, even though residing together in a homogeneous environment. Variations between certain species in frequency and length of the oestrous cycle seem to be accommodated to by parallel adjustments in the male, including extended sperm production or storage and continued secretory activity of accessory sex glands.

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P. H. Krutzsch and E. G. Crichton

Summary. The major reproductive events in the male eastern pipistrelle, are similar to those of other hibernating vespertilionids. The eastern pipistrelle stores epididymal spermatozoa throughout hibernation, a time when the testes are involuted but accessory gland activity is maintained. However, this species differs from others in that epididymal and testicular spermatozoa persist longer and the weights of the accessory glands are not strongly differentiated between winter and spring/summer. It is suggested that the reproductive period is extended in this species as a function of a more prolonged period of hibernation, resulting in only a brief period of sexual quiescence in mid-summer. The eastern pipistrelle (Pipistrellus subflavus) resembles the canyon bat (P. hesperus) in that some testicular spermatozoa persist during winter. Many aspects of the reproductive anatomy and chronology of these two species are similar; however, eastern pipistrelles apparently lack a seminal vesicle and possess a distinctly different baculum.

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E. G. Crichton, P. H. Krutzsch and R. Yanagimachi

Previous experiments have established that the long-lived spermatozoa of hibernating bats are resistant to the acrosome reaction and fertilization in vitro using conventional techniques. We tested the hypothesis that the membranes of these spermatozoa are more resistant to perturbation than those of other mammals. We exposed them to non-specific bilayer destabilizing agents and abrupt changes in incubation temperature and tested their response by observing their status (motility and viability) after a time interval compared with other mammals (golden hamster, rabbit, human). The results did not support the hypothesis. The inherent longevity of bat spermatozoa may thus be a function of some component other than unique resilience of their plasma membrane.