Surface views of spermatozoa as revealed by fracture-flip.
We have used fracture-flip to produce new, macromolecular-resolution images of the surface of boar spermatozoa. Over the head, acrosomal and postacrosomal regions display sharply demarcated, subtly different surface textures. The rim is particle-poor, as well as a region above the oblique cords over the posterior ring. The tail shows two morphologically distinct domains: (1) the principal piece is covered by a high density of parallel-helical strands and a high density of large globular particles; (2) the midpiece and the neck are covered by smaller particles with apparent random distribution. Rectangular surface specializations frequently seen near the annulus display a waffle-like texture. With the notable exception of the parallel-helical strands of the principal piece the fracture-flip images of the boar spermatozoon can be directly related to the freeze-fracture morphology of its plasma membrane.
Forsman
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Membrane Biology Section, NIH/NCI-FCRF, Frederick, Maryland 21701.
Pinto da Silva
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D000818:Animals; D002462:Cell Membrane / Q000648:ultrastructure; D005614:Freeze Fracturing / Q000379:methods; D008297:Male; D013077:Sperm Head / Q000648:ultrastructure; D013082:Sperm Tail / Q000648:ultrastructure; D013094:Spermatozoa / Q000648:ultrastructure*; D013552:Swine / Q000033:anatomy & histology*