Various deviations from classical 9 + 2 flagellar structure are found in sperm of insect species. In mature spermatozoa of a psocid, Psocus, the outer flagellar tubules are not straight, but are disposed in a long-pitched helix such that they form an angle of about 8° with a single dense rod located in the position usually occupied by the central pair. In young spermatids of Psocus the outer tubules are straight; thus, spiraling of the flagellar tubules occurs during the course of spermiogenesis. Spiraling of flagella also occurs in the cat flea Ctenocephalides felis. Variations in the number and morphology of the central element or elements occur in other insect species besides Psocus. Among the observed deviations from a central pair of tubules are a 9 + 0 tubule pattern in the sperm of three species of mayflies, a 9 + 1 tubule pattern in the sperm of two species of mosquitoes, and 9 + 7 tubules in sperm of two species of caddis flies. Spermatozoa of treehoppers vary in yet another respect from the typical 9 + 9 + 2 insect flagellum. These sperm tails branch into four long tails, three of which each contain two doublet and two singlet tubules while the fourth branch contains three doublet and three singlet tubules. The wide distribution of insects with aberrant flagella suggests that the variant forms have evolved independently.
Article| January 01 1969
EXCEPTIONS TO THE PREVAILING PATTERN OF TUBULES (9 + 9 + 2) IN THE SPERM FLAGELLA OF CERTAIN INSECT SPECIES
David M. Phillips
From the Department of Anatomy and the Laboratories for Human Reproduction and Reproductive Biology, Harvard Medical School, Boston, Massachusetts 02115.
Dr. Phillips' present address is Department of Biology, Washington University, St. Louis, Missouri 63130
Received: May 31 1968
Revision Received: August 23 1968
Online Issn: 1540-8140
Print Issn: 0021-9525
Copyright © 1969 by The Rockefeller University Press.
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David M. Phillips; EXCEPTIONS TO THE PREVAILING PATTERN OF TUBULES (9 + 9 + 2) IN THE SPERM FLAGELLA OF CERTAIN INSECT SPECIES . J Cell Biol 1 January 1969; 40 (1): 28–43. doi: https://doi.org/10.1083/jcb.40.1.28
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