Stratum Malpighii

Normal stratum corneum Granular layer Stratum malpighii Basal cel layer... 

In psoriasis the 50-A fibrils which start in the basal or most inferior cell of the stratum malpighii are never transformed into the 70-A fibril found in the normal stratum corneum. They remain as 50-A fibrils poorly integrated into the surrounding denser matrix and do not assume the nicely arrayed keratin packing found in normal horn cells. In addition keratohyalin granules are not found in the cells of the intermediate layer, and the cytoplasmic and nuclear contents of the cell are removed only to a very limited degree. An alternative picture involving lipid has been discussed by Swanbeck (S30, S31). 

Fig. 1. Sulfhydryl reactions. Human skin. Stratum Malpighii and stratum corneum of the epidermis are weakly reactive, as are the epithelia of sebaceous glands and the root sheaths. The hair cortex stains sparsely. (X45.)...

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