Fig 4 6 fig 4 5 fig 4 7 gap jxns found in other

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Unformatted text preview: eleton make up the “terminal bar” faintly seen by LM at the apical ends of some epithelial cells (arrow). Fig. 4-6 Fig. 4-5 Fig. 4-7 gap jxns found in other tissues, not just epithelia! Gap (or communicating) junctions (nexi) are for intercellular communication, rather than adhesion. Transmembrane proteins called connexins form hexameric complexes called connexons which have a hydrophilic pore, allowing small molecules to move from cell to cell. APICAL ENDS: Apical ends of columnar cells often have specialized structures. Network of actin filaments inside microvilli -this web is called a TERMINAL WEB. increase SA by 50 fold!!! Microvilli Fig. 4-8 Short projections, 1 micron long. Packed 2gether side by side. In a light mic picture (upperleft corner) -we see "stripes" -- this referred to as a BRUSH BORDER of the cell. Or STRIATED border. The most common of these are microvilli, usually present to increase the cell surface in cells specialized for absorption, forming the “brush / striated border.” Actin fila...
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