Look for plasma cells within the lamina propria of slide 29 View Image. Slide 40 (trachea, H&E) View Virtual Slide ![]() Neutrophils and macrophages are also present and both are discussed below. This region is also a loose, irregular connective tissue but can be so extensively infiltrated by white blood cells and plasma cells that the supporting fibers and ground substance are obscured. Now look at the region immediately underneath the intestinal epithelium, which is called the lamina propria View Image . You should be able to recognize a range of nuclear morphologies and be able to identify the cells as fibroblasts. Most of the rounded cells you may see in the submucosa are likely white blood cells (monocytes, macrophages, and occasional neutrophils) that have migrated out into the tissue. Look for more examples of fibroblasts and note that you rarely see much cytoplasm and that the nuclei of these cells can be quite condensed and hyperchromatic depending upon the plane of section or the metabolic state. Note that the nucleoplasm of a fibroblast has a generally fine stippled (dot-like) chromatin pattern with occasional coarse chromatin clumps (heterochomatin) and one or two nucleoli. These are fibroblasts View Image (as opposed to clusters of similar appearing elongate nuclei that are usually smooth muscle cells or Schwann cells in a nerve that you will learn to recognize soon). Look for elongated nuclei, usually solitary, from which a modest amount of tapered cytoplasm extends from either one or both poles of the nucleus. ![]() The background will be clear, reflecting a "ground substance"-rich connective tissue. The collagen of fibrous supporting tissues, the dermis of the skin, tendon, ligaments and bone is type I collagen, which provides tensile strength. In this area note the irregular, wavy collagen fibers arranged singly or in small groups. Look at the connective tissue in the submucosa which is the lighter staining area View Image between the intestinal epithelium and the smooth muscle layer. Slide 29 (small intestine, H&E) View Virtual Slide
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