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Muscle fiber typing is conventionally performed using mATPase enzyme histochemistry on cryostat sections. After pre-incubation of sections at pH 4.3, 4.6 and 10.3, based on the pattern of enzyme reactivity, the fibers can be classified in types I, II (subtypes A, AB and B) and the intermediate C (I and II) fibers. We have attempted to perform fiber typing of human psoas muscle by immunohistochemistry, using monoclonal antibodies R11D10 (specific for cardiac and type I skeletal myosin) and MY-32 (specific for fast muscle fibers) on cryostat as well as on paraffin sections. Staining of consecutive cryostat sections showed that type I fibers are R11D10 reactive whereas type II fibers are MY-32 reactive. Subtyping of type II fibers could not be performed by immunohistochemistry. Quantitative analysis of type I and II fibers showed that enzyme histochemical and immunohistochemical analysis are in close agreement.

We studied the distribution of type IV collagen and type VII collagen in the basement membranes of normal mucosa of the colon, adenomas, and adenocarcinomas using immunoperoxidase and immunofluorescence techniques. In normal mucosa, we found regular type IV collagen-positive basement membranes, lining vascular structures and mucosal epithelia. These basement membranes, however, lacked type VII collagen. In adenomas of the colon, intact basement membranes were observed through type IV collagen staining. Type VII collagen staining was also detected, but only in connection with dysplastic epithelium. Adjacent to the dysplastic epithelium in adenomas, histologically normal epithelium also showed type VII collagen staining along the basement membrane, but this was restricted to the epithelium of the luminal surface. These areas were also investigated for expression of keratins 8, 18, and 19, and keratins 5 and 8 (monoclonal antibodies NCL-5D3 and RCK 102, respectively), but altered differentiation was not detected using this technique. In adenocarcinomas of the colon, type IV collagen was irregularly deposited in the basement membrane of neoplastic tubules. Type VII collagen staining was detected only in well or moderately differentiated carcinomas and in higher amounts. Our findings therefore reveal a transient expression of type VII collagen in the transition of dysplastic epithelium into carcinoma, suggesting the involvement of type VII collagen in the process of early invasion.

Immunocytochemical detection of intrinsic components of the basement membrane (type IV collagen and laminin) was performed in biopsies of carcinoma in situ, dysplasia and hyperplasia of the laryngeal mucosa. We found a distinct and continuous basement membrane, containing both laminin and type IV collagen, at the border between epithelial cells and mesenchymal stroma in normal as well as in hyperplastic and dysplastic mucosa. In contrast, irregular discontinuities were found in some cases of carcinoma in situ and in invasive carcinoma. In addition, immunoreactivity for intracytoplasmic basement membrane components was noticed occasionally in neoplastic epithelial cells. In areas of inflammation, infiltration of leucocytes into the epithelium was occasionally accompanied by sharply defined small interruptions of the basement membrane. Our results indicate that immunohistochemical detection of basement membrane components can be of value for the demonstration of microinvasive growth in laryngeal cancer.

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