Uptake of yolk protein into coated vesicles (arrows) at the periphery of oocytes of the cockroach Periplaneta americana. Yolk protein binds to regions of the membrane with a prominent glycocalyx. Because yolk protein has a strong affinity for osmium, it is electron dense and appears prominently in electron micrographs. Images by Everett Anderson, Figures 57 (upper) and 58 (lower) from Chapter 2 (Specializations of the Free Surface) of 'The Cell, 2nd Ed.' by Don W. Fawcett M.D. A PDF copy of the accompanying chapter is available on the ASCB’s BioEDUCATE website.