An understanding of squamous metaplasia is the key to understanding the development of pre-malignant disease of the cervix. Metaplasia can mimic CIN in as much as it can produce abnormal cervical cytology and grossly abnormal colposcopy. Metaplasia may be mature or immature. Metaplasia in itself does not result in malignant or premalignant disease. However, the immature metaplastic cell seems particularly susceptible to carcinogens. The cells undergoing immature metaplasia have a low immune status. Hence if these cells are exposed to oncogenic virus the progression from atypical metaplasia to dysplasia is likely to be rapid. The purpose of Metaplasia is to produce cells more suitable to the adverse, altered or stressful environment around the tissue.