Ultrastructural aspects and reserve accumulation: The cytoplasm of the apical cells of the GTs is rich in organelles; mitochondria, dictyosomes, plastids, and ribosomes are prevalent; the ribosomes are either free or associated with segments of the endoplasmic reticulum (Fig.
The dictyosomes have from four-seven cisternae, and their peripheral regions liberate small and not very dense vesicles, that become dispersed in the cytoplasmic matrix (Fig.
The models involved the autogenous emergence of the endoplasmic reticulum, nuclei, and dictyosomes
and the autogenous or xenogenous evolution of flagella and microtubular and non-microtubular cytoskeletal structures, before the symbiotic acquisition of mitochondria and plastids.
The Eustigmatophyceae have been considered to be outside the Chromophyta by some authors because of the possession of a distinctive eyespot, the lack of a girdle lamella in chloroplasts and the absence of dictyosomes
from zoospores (Hoek, 1978; Hibberd, 1979).
Colleter cells have thin walls, dense cytoplasm, large nuclei, many mitochondria, rough endoplasmic reticulum, and abundant dictyosomes
hirsuta root hairs, Ridge (1988) identified three vesicle types in the sub-apical region: pyriformis vesicles found primarily in the apical dome; coated secretory vesicles located anywhere between the nucleus and the tip; coated vesicles [these were also described by Bonnett and Newcomb (1966) and Newcomb and Bonnett (1965)] associated with dictyosomes
and the plasma membrane, in regions of cytoplasm away from the apical dome.