Light micrograph from a cervical smear showing abnormal squamous epithelial cells constituting a case of carcinoma-in-situ (c.i.s.), or pre- invasive cancer of the cervix. The individual cells are severely dysplastic, being pleomorphic or of heterogenous form, with large nuclei that show evidence of cell divisions. Normally the superficial squamous cells would appear uniform with large cytoplasms and small centrally-placed nuclei, with cell division confined to the basal layer. The degrees of dysplasia range from mild, through moderate, to severe and c.i.s. They are graded CIN I, II and III respectively. Magnificat- ion: x40 at 35mm size.