Mesophyll cell electron micrographs

Figure 2. Scanning electron micrograph of a mesophyll cell of a dormant cotyledon of Buffalo gourd (Cucurbita foetidissima). Tissue was fixed in aqueous glutaraldehyde, dehydrated with ethanol and critically point dried. Note cell wall (W) and intracellular components including protein bodies (P) and emptied spherosomes that appear as a cytoplasmic reticulum.

Figure 3. Transmission electron micrographs of mesophyll cells of dormant cotyledons of A, Cucurbita foetidissima B, Cucurbita pepo C, Cucurbita palmata D, Cucurbita digitata E, Apodanthera undulata" Note cell wall (W), protein body (P), spherosome (S), globoid (G), and crystalloid (X). In each micrograph, the bar represents five microns. Reproduced from reference 14.

Figure 1. Source leaf minor vein phloem. (A) Autoradiograph of leaf tissues following l C-sucrose accumulation showing radioactivity (white) in veins. (B) Tracing of an electron micrograph of a cross section of minor vein, x, xylem, vp, vascular parenchyma cc, companion cell se, sieve element pp, phloem parenchyma, me, mesophyll cell. Reproduced with permission from Ref. 6. Copyright 1983. Annual Reviews.

Endosperm cells of a ryegrass, Lolium multiflorum, were grown in suspension culture and the cell walls recovered.261 The walls of the cultured cells were thicker than the walls in the seed. Electron micrographs indicated that the cell walls were similar to primary walls.261 The cell walls from the cultured cells contained arabinose, galactose, and xylose in the ratios of 7.3 1.9 10, and a trace of mannose was present.118 In these cell walls, as in the mesophyll cell-walls,257 glucose was present in high proportion. 

CAM cell vacuoles often appear filled with precipitations, probably due to tannins or tannin-like substances (see Fig. 2.5). Electron micrographs of von Willert and Kramer (1972) suggest membranous compartmentation within the vacuoles of Mesembryanthemum crystallinum. Also bladder-like vesicles extending from the cytoplasm into the vacuole were seen in the mesophyll cells of the same species. These vesicles consist of an envelope (double membrane) which encloses rather densely packed tubuli (Fig. 2.6) resembling lomasomes and interpreted as such by von Willert and Kramer. At the moment, there is no clear suggestion if these lomasome-like vesicles fulfill a specific role in CAM of Mesembryanthemum crystallinum. 

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