Springer Online Journal Archives 1860-2000
Summary Recent immunohistochemical studies have shown that basal cells in human prostatic epithelium are not myoepithelial cells. Since in the literature the Dunning tumor, originally described as a rat prostate carcinoma derived from the dorsolateral prostate of a Copenhagen rat, was reported to have myoepithelial cells, a comparative immunohistochemical and ultrastructural study was performed in the H-, HIF- and AT3-lines of the Dunning tumor, the male accessory sex glands (ventral, dorsal, lateral prostate, coagulating gland, bulbourethral gland) and the mammary gland of both Copenhagen and Wistar rats. Mono- and polyclonal antibodies directed against intermediate filament proteins (cytokeratin, desmin, vimentin) and the contractile proteins (α-actin, muscle type specific myosin, tropomyosin) were used along with phalloidin decoration of F-actin. As in the human prostate, none of the rat prostate lobes in either strain did contain basal cells expressing cytokeratin along with α-actin, myosin and tropomyosin. Cells representing fully differentiated myoepithelial cells, however, were present as anticipated in the mammary gland, the bulbourethral gland and the H-tumor line of the Dunning tumor. This finding is difficult to reconcile with the contention of a prostatic origin of the H-Dunning tumor. Further studies are required to classify the epithelial parental tissue in order to define the true origin of the H-Dunning tumor and the tumor lines derived thereof.
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