Fig. 3From: A new technical approach for preparing frozen biological samples for electron microscopyTEM micrographs of the alga Micrasterias denticulata (a, b) and the alga Klebsormidium crenulatum (c–g) after freezing (b, d, g) in comparison to 20 °C controls (a, c, e, f). a 20 °C control of Micrasterias shows single mitochondria (m), mucilage vesicles (mv), a part of the chloroplast (chl) and a part of the vacuole (v). bMicrasterias cell after − 2 °C freezing with aggregated and fused mitochondria (m), endoplasmic reticulum (er), dictyosome (d), mucilage vesicles (mv) and chloroplast (chl). c 20 °C control of Klebsormidium shows vacuole (v) and cytoplasm (cyt) with single mitochondrion (m), chloroplast (chl), dictyosome (d), multi vesicular body (mvb), peroxisome (p) and nucleus (n). dKlebsormidium after − 2 °C freezing shows chloroplast (chl), nucleus (n), peroxisome (p), vacuole (v) and cell wall (cw). e High magnification of 20 °C control of Klebsormidium shows double membranes (arrows) and cristae (asterisks) of mitochondrion (m) and chloroplast (chl). f High magnification of 20 °C control of Klebsormidium with chloroplast (chl) and cytoplasm (cyt), surrounded by the plasma membrane with the typical two-leaflet structure (arrows) and cell wall (cw). g High magnification of Klebsormidium frozen at − 2 °C shows peroxisome (p), vacuole (v), cell wall (cw) and double membranes (arrows) of chloroplast (chl) and nucleus (n)Back to article page