Collagen, type electron micrograph

Electron micrograph of a polygonal network formed by association of collagen type IV monomers. 

Ronziere, M-C., Herbage, B., Herbage, D., and Bemengo, J-C. (1998). Fourier analysis of electron micrographs of positively stained collagen fibrils Application to type I and II collagen typing. Int. J. Biol. Macromol. 23, 207-213. 

Fig. 1. (A) Scanning electron micrograph of human skin. The epidermis has pulled away from part of the basement membrane. (B and C) Transmission electron micrograph through the epidermal-dermal junction of human skin. Keratinocytes (KF) are the cells in the human epidermis. LD, The lamina densa of the basement membrane LL, the lamina lucida. Typical anchoring fibrils (AF) formed from type VII collagen are shown at higher power in C. Courtesy of Dr. K. Holbrook, University of Washington.

Fig. 3. Electron micrographs of type IV collagen (a), laminin (b), and nidogen (c) molecules after rotary shadowing. Bar in a-c, 50 nm.

Figure 3.29. Relationship between proteoglycans and collagen fibrils in tendon. Transmission electron micrograph showing positive staining pattern of type I collagen fibrils from rabbit Achilles tendon stained with quinolinic blue. Proteoglycan filaments (arrows) are shown attached to collagen fibrils.

Reed and Rudall (182) studied the cuticle of the earthworm Allolobo-phora longa), securing by an ingenious stripping technique electron micrographs of layers of the crossed collagen-type fibrils secreted by columnar epithelial cells. Most important for the present discussion they reported inability to observe in their material the banded appearance characteristic of the usual connective tissue fibrils. 

FIGURE 3. A transmission electron micrograph of a section of an alveolar septum of lung tissue of a rat pup exposed to nicotine via the placenta and mother s milk. Swelling of the endothelial cell (asterisks) of the blood-air barrier occurs. Note the focal degeneration of the endothelial cell cytoplasm (star). The blood-air barrier is composed of the endothelial cell (asterisks), type I cell (double arrowheads), and the basement membrane between these cells. Swollen mitochondria can be seen in the interstitial cells (arrowheads). Collagen fibers also occur (arrows), cap = capillary. 

Figure 2. Scanning electron micrographs of the two types of collagen conduits (A) cross-sectional view, small pore conduit (B) lumenal surface view, small pore conduit (C) cross-sectional view, large pore conduit (D) lumenal surface view, large pore conduit. 

Fig. 8. The network structure of type IV collagen as deduced from electron microscopy of fragments solubilized with proteases (Timpl et at., 1981). The top left micrograph shows the short form of the 7 S region. In the top right, a more limited enzyme digestion allows a portion of the helical domain of each molecule to remain linked to the 7 S domain. The bottom left micrograph shows isolated dimeric NCI fragments and, at the lower right, dimeric triple helical material connected in the center by the NCI domain.

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