ISSN:
1615-6102
Keywords:
Differentiation
;
Heterochronic lysis
;
Polarity
;
Root protophloem sieve elements
;
Triticum aestivum
;
Ultrastructure
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Summary Developing protophloem sieve elements in roots of wheat are arranged in single vertical files. In the last immature differentiating sieve element bearing ribosomes the proximal end of the cytoplasm displays a diluted appearance in contrast to the distal end where the cytoplasm exhibits a considerably increased electron density. Differences can also be observed in ribosome quantity, organelle ultrastructure and the time of initiation of cell component degradation, those at the proximal end disorganizing first, suggesting a nonsimultaneous disorganization of the cell components in the two areas. This phenomenon, termedheterochronic lysis, is presumably an expression of an existing polarity not detectable in younger stages, but it might also be the result of an asynchronous enzymatic activity.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01354235
