MICROSPHERE UPTAKE BY THE INTESTINE OF WHITE LEGHORN CHICKENS

A study was conducted to determine the effective size for latex micros phere uptake in the intestine of white leghorn chickens. Three trials were conducted in which ligated intestinal segments of anesthetized 8- wk-old chickens were injected with 0.2-, 0.5-, 2-, 6-, 10-, or 20-mu d iameter fluoresceinated latex microspheres. Microspheres were counted in brush border, epithelium, and lamina propria of each intestinal seg ment, liver, and spleen. After 1 hr, the 0.2-, 0.5-, and 2-mu microsph eres were oriented along the brush border of epithelial cells and micr osphere uptake into the epithelium and lamina propria was observed in the duodenum, ileum, cecum, cecal tonsil, and colon. Uptake of microsp heres of 6, 10, and 20 mu diameter into epithelium and lamina propria was not observed in any intestinal segment. Also, no microspheres of a ny diameter were observed in sections of liver and spleen to suggest t hat there was no appreciable entry of microspheres into the bloodstrea m within 1 hr after administration. The results indicated that uptake of microspheres by the chicken intestine is a size-dependent process w ith microspheres less than or equal to 2 mu being taken up to an equal extent by most segments of intestine.