Villus-crypt axis

Fihn, B. M., A. Sjoqvist, and M. Jodal. Permeability of the rat small intestinal epithelium along the villus-crypt axis effects of glucose transport, Gastroenterology 2000, 119, 1029-1036... 

Fig. 5. Rate of cholesterol synthesis in the mucosa along the villus-crypt axis in the rat intestine. Enriched mucosal cell fractions were obtained from the mucosa by EDTA treatment and these viable cells were subsequently incubated in the presence of [ HJwater. Panels A and B represent the rate of cholesterol synthesis expressed as the nmoles of acetyl-CoA units incorporated into cholesterol/h/mg of cell protein in the jejunum and ileum, respectively. Panels C and D represent the total activity found in the isolated cell fractions talcing into account the cell protein recovered in each fraction. The columns and bars represent means + 1 S.E.M.

Fig. 8. Rate of LDL-cholesterol uptake in the mucosa along the villus-crypt axis in the rat intestine. The rates of LDL-cholesterol uptake were determined by measuring the tissue clearance of [ C]sucrose-labeled LDL in vivo and then isolating different cell fractions from the mucosa. These clearance values were multiplied by the LDL-cholesterol concentration in plasma and expressed as the nmoles of LDL-cholesterol taken up per h/mg of cell protein (panels A and B) or as the percentage of total mucosal uptake found in each cell fraction (panels C and D). The columns and bars represent means +1 S.E.M.

The relative importance of each of these contributions to pool C is likely to be different in epithelial cells located at different points along the villus-crypt axis. The fact that cholesterol derived from synthesis and from the uptake of LDL is critically important for membrane formation and differentiation is suggested by the finding that 70-80% of total mucosal sterol synthetic activity and LDL transport activity are localized to the immature cells of the lower villus and crypt regions in both the proximal and distal intestine. In the mature absorptive cells of the upper villus in the jejunum, where most sterol absorption takes place, the rate of cholesterol synthesis appears to be suppressed. In the absence of fat absorption, cholesterol newly synthesized in these cells apparently is sloughed into the lumen and not reabsorbed. However, with active triglyceride absorption cholesterol synthesis in these cells is increased and a portion of this sterol appears in the intestinal lymph. Only under this condition does pool B apparently supply sterol for lipoprotein formation. 

Figure 3 Schematic of crypt-villus cellular axis and components of villus central lac-teal. (From Ref. 77.)...

Martial MA, Carlson SL, and Madara JL [1987] Partitioning of paracellular conductance along the ileal crypt-villus axis a hypothesis based on structural analysis with detailed consideration of tight junction-structure function relationships. J Membr Biol 80 59-70... 

Meddings, J. B., DeSouza, D., Goel, M., and Thiesen, S. (1990). Glucose transport and microvUlus membrane physical properties along the crypt-villus axis of the rabbit. /. Clin. Invest. 85,1099-1107. 

Tissue-based systems evaluation of transport mechanism segmental absorption evaluation evaluation of absorption enhancing strategies other tissues (nasal, buccal) comparison between species possible presence of nerves (e.g., local control, crypt-villus axis) transporters and enzymes as in vivo limited database viability of tissue low throughput limited access to (human) tissue... 

Differentiates between adsorption and absorption crypt-villus axis ion and water flow... 

Pageot, L.-P, Perreault, N., Basora, N., Francoeur, C., Magny, P, and Beaulieu, J.-F. 2000. Human cell models to study small intestinal functions recapitulation of the crypt-villus axis. 

---