ISSN:
0886-1544
Keywords:
acrosome-reacted sperm
;
coiled filament
;
intermediate filament
;
quick-freeze
;
deep-etch technique
;
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Medicine
Notes:
A novel structure named the truncated cone was located in the apex of the acrosomal vesicle right beneath the outer acrosomal membrane of abalone sperm head. This truncated cone structure was composed of about 12 helically coiled filaments, each 3.5-3.6 μm long with a diameter of 8-12 nm, forming a tightly compressed helicoid. During the acrosome reaction, the truncated cone elongated more than three times the original height and transformed into a thin cylinder by further coiling up of the filaments from the initial 2.5 to final 5 turns. The diameter and the lenght of each filament did not change during the elongation of the truncated cone into thin cylinder.Calculation from the equation of helical movement (spiral motion) applying the actual values of the truncated cone structure measured by electron microscopy gave the theoretical values nearly coincident with the actual measurements. The computer animation simulated the process of the movement of the coiled filaments composing the truncated cone and suggested that the elongation of the truncated cone into thin cylinder can be elucidated as a helical movement of the coiled filaments keeping their length constant.Quick-freeze, deep-etch electron microscopy further revealed that each of the coiled filaments was characterized by its beaded configuration, closely resembling that of the intermediate filametns of our previous results by immunoelectron microscopy and immunoblot analysis. The movement of the helically coiled filaments of the truncated cone may provide first example of the intermediate filaments to participate in motility and fertilization. © 1993 Wiley-Liss, Inc.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cm.970250209
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