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Updated: Feb 2, 2026

Biophysical Characterization of Flagellar Motor Functions
Published on: January 18, 2017
The peculiar structure of the flagellar axoneme in Coccinellidae (Insecta-Coleoptera)
Romano Dallai1, David Mercati1, José Lino-Neto2
1Dipartimento Scienze della Vita, Università degli Studi di Siena, Via Aldo Moro 2, 53100 Siena, Italy.
Abstract:
The ultrastructure of the complex organisation of the spermatozoa in Harmonia axyridis and Adalia decempunctata (Coccinellidae) was studied, with particular emphasis on the origin of the anterior shifting of the axonemal structure, which becomes parallel to the nucleus in the sperm flagellum. In studying the spermiogenesis, a centriolar remodelling was observed with the long centriole, present in the early spermatids, transformed in the spermatozoa into an exceptionally long and narrowed basal body (about 0.16 × 3.5-4.0 μm long) displaying a 9 + 0 microtubular pattern in the proximal part and a 9 + 2 pattern in the following part; this is a characteristic not observed in any other pterygotan insect. The sperm also have a very long acrosome surrounded by a dense layer of material extending along the whole basal body. These two uncommon features were discussed in the light of sperm movement.
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