ISSN:
1615-6102
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Summary The sieve areas inPinus resinosa consist of groups of plasmalemma-lined pores joined in the middle of the wall by large compound median cavities. Numerous membranes extend into the pores from aggregates of smooth, tubular endoplasmic reticulum opposite the sieve areas and merge in the median cavities. A compound median cavity arises through the union of smaller simple median cavities, each of which is initially associated with a single plasmodesma. Callose platelets were not associated with developing pores, but the pores of most fully-developed sieve areas were lined with callose. Sieve cells also have connections with albuminous cells. The connections on the sieve-cell side of the wall are similar to sieve-area pores, those on the albuminous-cell side to plasmodesmata. These connections also are associated with compound median cavities containing many membranes. The albuminous cells contain protoplasmic components similar to those of other parenchymatous cells including chloroplasts, cytoplasmic fibers, and microbodies.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02075947
