10 April 1992
Vol 256, Issue 5054

About The Cover

Polarized light micrograph of asters (systems of microtubules emanating from centrosomes; these microtubules contribute to the mitotic spindle during cell division) in cytoplasmic lysates prepared from oocytes of the Atlantic surf clam, Spisula solidissima. A method of duplicating centrioles outside of the confines of the cell has now been developed. See page 219. [Photomicrograph by Robert E. Palazzo]