The purpose was to evaluate the cells of the epithelium in Cervical Intraepitelial Neoplasia (CIN) and its progression to cancer. 52 samples with a diagnosis of NIC were compared with 13 samples of invasive cervical cancer and 4 samples from patients with normal Pap smear under their consent. An assessment was conducted for colposcopy collections of samples of epithelial tissue, of the cervix from 0.5 cm. The samples were prepared for study with transmission electron microscope, which was followed by fine cut technique. Electron micrographs were taken 3 per sample and the program Image tools 0.8 beta was used. The data were analyzed with Statistical processor SPSS version 18. Cancer samples presented cellular necrosis and nuclear remnants (A), denatured cell chromatin (B), pycnotic cytoplasm (C), cores of irregular contours (D) hyperchromatic nuclei (E) absence of organelles (F), deformed erythrocytes (G), degenerated capillaries (H), mast cells attendance (J), degenerated mitochondria (K), alteration of the collagen (Q) and absence of desmosomes (Y). CIN I showed 22% hyperchromatic nuclei, 13% of mast cells and 11% of degenerate capillaries. CIN II showed 20% vacuolization of the cytoplasm and 12% denatured chromatin. CIN III showed 20% of alteration of collagen and 12% no showed desmosomes. In all the microphotographs of CIN samples studied, morphological alterations observed evidenced cell necrosis. The CIN I presented major hyperchromatic nuclei, cell necrosis, mast cells and degenerate mitochondria, in the case of CIN II, the cells showed a greater process of vacuolization of the cytoplasm. The alterations of the collagen and the absence of desmosome, characterized the morphology of the cells in CIN III.

Keywords: Progression, ultrastructure, cervical intraepitelial neoplasia (CIN), cancer.