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Unformatted text preview: ments in microvilli allow movements
and connect with a
“terminal web” (TW) of
similar microfilaments in
Major fxn: INCREASE SURFACE AREA AT APICAL
END OF CELL, THUS INCREASING ABSORPTION! Epithelial cells that are specialized for rapid absorption at their apical ends usually have
many microvilli, pinocytotic vesicles, many mitochondria, and long invaginations or folds
of the basal membrane, with mitochondria aligned along these membrane folds. Fig. 4-29 Another apical specialization: Stereocilia – resemble long,
branched microvilli and also are mainly to increase absorption by
cells. Stereocilia are best seen on cells of the tall epithelial cells
lining the epididymis.
MOST CELLS HAVE MICROVILLI AND NOTTTT STEREOCILLIA.
FOUND IN LINING OF EPIDIDMYS, WHERE SPERM ARE STORED
TEMPORARILY. PROBS HAVE SAME FXN AS MICROVILLI -- TO
PROMOTE ABSORPTIONS -- BUT THEYRE LONGER, MODIFIED
MICROVILLI. Fig. 4-9 Apical specializations: Cilia – more robust and motile than
stereocilia, for movement of cells or extracellular material.
Common on epithelial cells lining respiratory system. With
the TEM each cilium is seen to have 9 microtubule (MT)
doublets surrounding 2 more MT...
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- Spring '14