Argyrophilic cells and ectocervical epithelium.

The purpose of this study was to determine the nature of the argyrophilic cells in the ectocervix and to analyze the different morphologic varieties of argyrophil cell-containing ectocervical epithelia, notably to reappraise the degree of analogy with transitional epithelium. A systematic study of 39 ectocervices was carried out using histochemical and immunohistochemical techniques. Immunodetection of cytokeratins was used to specify the differentiation of the ectocervical linings. Argyrophilic cells were detected in 43% of our specimens. They have been found in several varieties of ectocervical lining: normal-appearing or hyperkeratotic squamous epithelium, "transitional-like" epithelium extending onto the portio, and immature squamous metaplasia from the transformation zone. The term "transitional-like" refers to a stratified nonsquamous epithelium that differs from true urothelium by the absence of superficial differentiation leading to the layer of "umbrella" cells. Two main types of argyrophilic cells have been delineated: serotonin cells and Merkel-type cells. The nature of the argyrophilic cells was dependent on the type of epithelium: Serotonin cells were essentially associated with "transitional-like" epithelium and Merkel-type cells with squamous epithelium. The latter cells were particularly frequent in hyperkeratotic squamous epithelium from uterine prolapse, reinforcing the homology with epidermis.