The plastids of plants germinated in the dark are termed etioplasts and possess quasi-crystalline structures termed prolammelar bodies that contain the phospholipid materials and chlorophyll precursors that are converted to green chloroplasts in response to light. The micrograph shows a corn (Zea mays) etioplast fixed after brief exposure to light. The prolamellar body has largely been transformed into thylakoid membranes that are starting to assume their mature stacked conformation. Other images in this group show the prolamellar body.
Zea mays seeds were germinated in the dark, briefly exposed to light, and segments of coleoptile, excised, fixed with glutataldehyde, post-fixed with osmuim tetroxide, and embedded in epoxy resin. Thin sections were cut, stained with uranyl acetate and lead citrate, and observed using a Philips 300 transmission EM. Images were recorded on film.
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