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 disappeared and thylakoid membranes are starting to form and stack.
Biological Process: C4 photosynthesis, Plastid organization, Chloroplast organization, Etioplast organization
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.
Author: Chris Woodcock
Source: The Cell: An Image Library
