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STRUCTURE AND DEVELOPMENT OF THE SIEVE‐ELEMENT PROTOPLAST IN THE HYPOCOTYL OF PINUS RESINOSA
Author(s) -
Neuberger Damian S.,
Evert Ray F.
Publication year - 1974
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1974.tb12254.x
Subject(s) - hypocotyl , biology , endoplasmic reticulum , sieve (category theory) , plastid , plasmodesma , osmium tetroxide , ultrastructure , botany , primordium , cotyledon , paraformaldehyde , glutaraldehyde , biophysics , immunogold labelling , microbiology and biotechnology , electron microscope , biochemistry , chloroplast , chemistry , mathematics , physics , organic chemistry , combinatorics , gene , optics , chromatography
Hypocotyl tissue of Pinus resinosa Ait. was fixed in glutaraldehyde‐paraformaldehyde and postfixed in osmium tetroxide for electron microscopy. Although young sieve cells contain all the components characteristic of young, nucleate cells, they can be identified early in their development. Increase in wall thickness occurs early and rapidly. Concurrently, the plastids, which already contain starch granules, form both crystalline and fibrillar inclusions. As the sieve cell approaches maturity, an extensive network of smooth, tubular endoplasmic reticulum (ER), which becomes mostly parietal in distribution, is formed. At maturity, massive aggregates of this ER occur on both sides of sieve areas. These ER aggregates are interconnected with one another longitudinally by the parietal ER. In addition, the mature, plasmalemma‐lined sieve cell contains a degenerate nucleus, mitochondria, and intact plastids. Dictyosomes, ribosomes, and vacuolar membranes are lacking. P‐protein is not present at any stage of development.