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The sea urchin egg jelly coat is a three‐dimensional fibrous network as seen by intermediate voltage electron microscopy and deep etching analysis
Author(s) -
Bonnell Barry S.,
Larabell Carolyn,
Chandler Douglas E.
Publication year - 1993
Publication title -
molecular reproduction and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.745
H-Index - 105
eISSN - 1098-2795
pISSN - 1040-452X
DOI - 10.1002/mrd.1080350212
Subject(s) - electron microscope , scanning electron microscope , sea urchin , dehydration , transmission electron microscopy , swelling , ultrastructure , microscopy , biology , materials science , biophysics , anatomy , composite material , optics , nanotechnology , biochemistry , microbiology and biotechnology , physics
The egg jelly (EJ) coat which surrounds the unfertilized sea urchin egg undergoes extensive swelling upon contact with sea water, forming a threedimensional network of interconnected fibers extending nearly 50 μm from the egg surface. Owing to its solubility, this coat has been difficult to visualize by light and electron microscopy. However, Lytechinus pictus EJ coats remain intact, if the fixation medium is maintained at pH 9. The addition of alcian blue during the final dehydration step of sample preparation stains the EJ for visualization of resin embedded eggs by both light and electron microscopy. Stereo pairs taken of thick sections prepared for intermediate voltage electron microscopy (IVEM) produce a threedimensional image of the EJ network, consisting of interconnected fibers decorated along their length by globular jelly components. Using scanning electron microscopy (SEM), we have shown that before swelling, EJ exists in a tightly bound network of jelly fibers, 50–60 nm in diameter. In contrast, swollen EJ consists of a greatly extended network whose fibrous components measure 10 to 30 nm in diameter. High resolution stereo images of hydrated jelly produced by the quick‐freeze/deep‐etch/rotary‐shadowing technique (QF/DE/RS) show nearly identical EJ networks, suggesting that dehydration does not markedly alter the structure of this extracellular matrix. © 1993 Wiley‐Liss, Inc.