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Title: CIRCADIAN RHYTHM OF SPERM RELEASE FROM MOTH TESTIS: ULTRASTRUCTURAL STUDY OF TRANSEPITHELIAL PENETRATION OF SPERM BUNDLES

Author
item GIEBULTOWICZ, JADWIGA - OREGON STATE UNIVERSITY
item WEYDA, FRANTISEK - CZECH ACADEMY OF SCIENCES
item ERBE, ERIC
item WERGIN, WILLIAM

Submitted to: Journal of Insect Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/6/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: The gypsy moth is an insect that causes millions of dollars worth of damage on an annual basis. Spraying programs to control this insect are expensive and need to be repeated annually. To identify other potential methods that could be used to control this pest, a study was undertaken to describe how reproduction occurs in the male. The reproductive cells of the gypsy moth were examined with two types of microscopes called a scanning electron microscope and a transmission electron microscope. The studies indicated that sperm release was controlled by a light sensitive "clock" that initially triggered the separation of specialized "gate" cells and allowed the sperm to leave the testis. This process was restricted to six hours each day. The factors that stopped the process were not determined. These data will provide scientists with an understanding of the cellular mechanism of sperm release in the gypsy moth, as well as in other harmful insects, and will be utilized by scientists to develop safe, innovative strategies for controlling these insect pests.

Technical Abstract: Release of bundles of elongated spermatozoa from the testis into the vas deferens is a critical step in insect reproduction. In moths, this release is controlled by a circadian clock that restricts the daily exit of bundles to a specific temporal gate. To be released, sperm bundles must penetrate the terminal epithelium. The sequence of cellular events associated with the daily cycle of sperm release was investigated with a combination of scanning and transmission electron microscopy. Preceding release, cytoplasmic processes of adjacent epithelial cells were interdigitated, forming a solid barrier between the testis and the vas deferens lumen. At the beginning of the release cycle, sperm protruded this barrier while the terminal epithelial cells underwent changes in their shape and position. Subsequently, the cyst cells enveloping the bundles broke down, allowing spermatozoa to leave the testis through exit channels formed between the epithelial cells. After penetration of the sperm ceased, cyst cell remnants and other cellular debris were released into the vas deferens lumen, and the epithelial barrier was reconstructed through phagocytic activity of its cells. These data provide a foundation for understanding the cellular mechanism of sperm release in insects.