Microvillar cells

Moran D.T., Rowley J.C. and Jafek B.W. (1982). Electron microscopy of human olfactory epithelium reveals a new cell type microvillar cell. Brain Res 253, 39-46. 

Rowley JC III, Moran DT, Jafek BW. 1989. Peroxidase backfills suggest the mammalian olfactory epithelium contains a second morphologically distinct class of bipolar sensory neuron The microvillar cell. Brain Res 502 387-400. 

The supporting cells of the olfactory epithelium separate and partially wrap the ORNs. Their apical surface, in humans and some other vertebrates, is covered with microvilli, which project along with the olfactory cilia into the mucous layer. A third cell type, the microvillar cells, present at about one-tenth the number of the ORNs in... 

This fraction was termed Haemonchus galactose-containing glycoprotein complex (H-gal-GP). The microvillar surface of the intestinal cells of worms retrieved from vaccinated lambs was coated with sheep immunoglobulin and protection observed, over a series of trials, was correlated with systemic antibody titre (Smith et al., 1999). 

Membrane extracts from adult H. contortus were enriched 24-fold for cysteine protease activity by passage over a Thiol-Sepharose affinity column and the proteins obtained (abbreviated as TSBP) were clearly localized to the microvillar surface of the intestinal cells (Knox et al., 1995,1999). TSBP comprised a prominent 60 kDa protein and several minor bands between 35 and 45 kDa and 97 to 120 kDa (Fig. 13.2). Protease activity at 38, 52 and 70 kDa was attributable to cysteine proteases and at 70 and 88 kDa to serine/metalloproteases, as judged by inhibition analyses. Lectin-binding studies showed that most of the TSBPs were glycosylated. Expression library... 

FIGURE 5-3 Immunocytochemical localization of the Na,K pump in choroid plexus. Choroid plexus contains epithelial cells with intensely stained microvillar and intermicrovillar plasma membranes. The basal and lateral plasma membrane surfaces are not stained. Bar = 2 im. (With permission from reference [81].)... 

Morphological studies show that SFV particles bound to BHK-21 cells are preferentially associated with the microvillar projections of the cell surface membranes (Helenius et al., 1980). Many of the virions which are not bound to microvilli (5% of all the cell surface viruses) are located in coated pits. The coated pits are invaginations of the plasma membrane, with a characteristic electron-dense coat composed of clathrin and other proteins on the cytoplasmic face (Pearse and Bretscher, 1981). Many of the coated pits are localized close to the base of microvilli. 

Hairy cell leukaemia This designation is based on the microvillar hairy surface of the tumour cells. It is con-... 

Thereafter the ookinete encounters the microvillar network and binds to the mid-gut epithelium. Although there are an array of possible receptors on the mid-gut epithelial cells little is known about their significance other than that sialic acid-like moieties are involved in the binding of the ookinete to the isolated mid-gut epithelium and that these interactions are blocked by the expression of the peptide SMI (PCQRAIFQSCIN) (Ito et ah, 2002) or pre-treatment of the epithelium with snake or bee venom phospholipase 2 (Moreira et ah, 2002 Zieler et ah, 2001). 

Aminopeptidase P is present in the microvillar membranes of pig and human kidney, and membrane-bound forms are also present in rat intestine and lung, bovine lung and guinea pig kidney. Soluble forms occur in rat serum and brain, human platelets and guinea pig serum, and it has also been characterized from human leukocytes. It is one of a group of cell-surface proteins anchored in the lipid bilayer by glycolyl-phosphatidylinositol (see Membrane lipids). 

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