Ultrastructure of detergent-resistant cytoskeletons in the noncortical domain of sea urchin eggs as revealed by the quick-freeze deep-etch technique.
The ultrastructure of detergent-resistant cytoskeletons in the noncortical cytoplasm of sea urchin eggs was studied by quick-freeze, deep-etch electron microscopy. Two different cytoskeletal organizations were identified in the detergent-treated sea urchin eggs. They were distinguished by the presence or the absence of long actin filaments and probably correspond to the cortex and the noncortical cytoplasm, respectively. The non-cortical cytoplasm was composed of a complex network (designated here as the ground network) of filaments 6 to 13 nm in diameter, that interconnected aggregates of small globular materials, yolk granules and a meshwork of uniform filaments (8-9 nm in diameter). The 6 to 13 nm filaments comprising the ground network were branched and associated with filaments of the same or other sizes, resulting in the formation of an extremely complex network. The meshwork of 8-9 nm filaments was homogeneous in composition and constitutes a novel structure which has not been previously described. The 8-9 nm filaments were connected to one another at their ends, forming a meshwork of polygons. Meshworks, ranging up to 3 microns in diameter, were distributed throughout the non-cortical cytoplasm of the egg. Similar cytoplasmic structures were also observed in fertilized eggs.
Hisanaga
S
S
Department of Anatomy and Cell Biology, Faculty of Medicine, University of Tokyo, Japan.
Endo
S
S
Hirokawa
N
N
Sakai
H
H
Pudles
J
J
D000199:Actins / Q000648:ultrastructure; D000818:Animals; D003599:Cytoskeleton / Q000648:ultrastructure*; D003902:Detergents; D004351:Drug Resistance / Q000502:physiology; D005260:Female; D005613:Freeze Etching; D010063:Ovum / Q000648:ultrastructure*; D012617:Sea Urchins
D000199:Actins; D003902:Detergents