Cervical biopsies were taken from women with abnormal Papanicolaou smears and from normal women serving as con trols, using the colpomicroscope as an aid in localizing lesions on the exposed portion of the cervix. Half of each biopsy was processed for light microscopy, and the other half was proc essed for both phase contrast and electron microscopy. The fine structure of dysplasia and carcinoma in situ was compared with normal control epithelium. The dysplastic lesions differed markedly from

more »

... e normal ; there were changes in nuclear size, contour, and chromatin distribution. Cytoplasmic constituents varied in amount and distribution. Cell surfaces and inter cellular contacts were altered and were progressively more ab normal as the severity of the dysplastic lesion increased. It was often difficult to distinguish between dysplasia and carcinoma in situ at the ultrastructural level, since the lesions had similar fine structural alterations and differed from one another only in degree. APRIL 1968 703