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The spermatozoon of Branchiostoma lanceolatum L

1972; Wiley; Volume: 136; Issue: 2 Linguagem: Inglês

10.1002/jmor.1051360206

1097-4687

B. Baccetti, A. G. Burrini, Romano Dallai,

Geology and Paleoclimatology Research

Abstract Under the electron microscope, the spermatozoon of Branchiostoma lanceolatum shows a spherical nucleus deeply grooved along its caudal third, a bistratified acrosome enriched by plentiful subacrosomal material, two centrioles, mitochondria fused into a single mass surrounding the centriolar region which is highly asymmetrical, a 9 + 2 flagellum tilted with respect to the longitudinal symmetry axis of the nucleus. The sperm of Branchiostoma shares the overall features of that of the Tunicata and fits in perfectly with the phylogenetic position of the Leptocardia.