Fig.3.

TEM micrographs of ultrathin sections of high-pressure frozen and freeze substituted interphase cells of M. denticulata. (a) Dictyosomes with adjacent ER cisterna at cis- and trans-side. Trans-most cisterna is chain-like constricted. Large mucilage vesicles (MV) are in contact with rims of trans-cisternae. Two MVBs (arrows) are located in close proximity to the trans-Golgi side and to a trans-ER cisterna. (b) MVB (arrow) is in contact with vacuolar membrane. translucent vesicles (arrow head) are in contact with trans-dictyosomal cisterna and MVB. ER = endoplasmic reticulum. (c) Representative MVB of Micrasterias with intraluminal vesicles. (d) Trans-side of dictyosome (D) with stack of mucilage vesicles (MV). Three MVBs (arrows) are in close proximity to the dictyosome and to a trans-ER cisterna. ER = endoplasmic reticulum. (e) Dictyosome and parts of the enwrapping ER. Contact between MVB (arrow) and part of a trans-ER cisterna visible. MV = mucilage vesicle; ER = endoplasmic reticulum; P = Plastid. (f) Part of a dictyosome and MVB attached to an ER cisterna. ER = endoplasmic reticulum. (g,h) MVBs in spatial contact with small electron-dense vesicle (arrow) and with larger translucent vesicle (arrow head). (i,j) MVBs attached to mucilage vesicles (MV). (j) Intraluminal vesicle of MVB discharged into upper mucilage vesicle (framed area). M = mitochondrion.