An electron microscopic study of carcinoma in situ and invasive carcinoma of the cervix uteri.

Abstract

Summary A comparative study between normal cervical stratified squamous epithelium, squamous-cell carcinoma in situ , and invasive squamous-cell carcinoma of the cervix has been carried out by electron microscopy. The nuclei of malignant tumor cells reveal the following notable alterations: increased nuclear membrane infoldings, increased density of chromatin granules just inside the nuclear membrane, and enlargement of nucleoli with more prominent differentiation between dense and finely granular areas. These changes are more prominent in invasive carcinoma than in carcinoma in situ . In the cytoplasm, mitochondria are more numerous than in comparable normal cells, and they are enlarged and swollen. Glycogen is absent from invasive carcinoma cells but present as occasional small droplets in the cytoplasm of carcinoma in situ cells. Attachment plates are still present between carcinoma cells, but they are less numerous and not so regularly arranged as in normal epithelium. Also, there is an absence of the usual dense cytoplasmic plaque at the attachment plates in some carcinoma cells. Cytoplasmic villous projections are present at the cell membrane of carcinoma cells, while they are not found in normal cervical epithelium. The basement membrane is found to be complete and intact in carcinoma in situ , but it is straighter than normal. In invasive carcinoma, the basement membrane is usually absent but may be present in imperfect form. Where the basement membrane is absent, small protrusions of carcinoma cell cytoplasm in the adjacent stroma can be seen, apparently representing the ultrastructural aspects of invasion by malignant neoplastic cells.