Fine structure of human cervical intraepithelial neoplasia in vivo and in vitro

Ultrastructural variations and assessment of malignant transformation risk in oral leukoplakia

Oral cancer is the most common malignancy in India, having a well defined precancerous state, leukoplakia. Various follow-up studies have shown that only 4 to 18% of oral leukoplakia lesions subsequently progress into invasive malignancy over a period of time. This study evaluates the potential of electron microscopy in the early detection of malignant changes in leukoplakia. The study revealed that of the 25 leukoplakia lesions examined, 7 showed changes akin to malignancy. Predominant ultrastructural alterations observed were reduplication and discontinuity of the basal lamina, basal cells with pleomorphic and bizarre nuclei containing perichromatin and interchromatin granules, prominent intercellular spaces and poorly formed desmosomes. Since none of these changes were evident under light microscopy the study demonstrates the value of electron microscopy in evaluating oral carcinogenesis. A long term follow-up of such patients is needed to understand the prognostic implications of these ultrastructural variation and how they can be used as a base line for better light microscopic evaluation.

Spreading of non-transformed and transformed cells

Mechanisms of cellular reactions responsible for the spreading of non-transformed cultured tissue cells on the surface of various substrata and relationships of these reactions to the control of cell proliferation are reviewed; the special role of the membrane-cytoskeleton interactions leading to extension and attachment of pseudopods is stressed. Transition of cells from non-transformed to transformed phenotype is characterized by decreased spreading and by decreased dependence of proliferation on spreading. Manifestations of both of these spreading-associated changes are reviewed and their possible mechanisms are discussed. It is suggested that cell transition to transformed phenotype involves shift of an equilibrium between the reactions induced by the two groups of membrane-bound ligands: those attached and those not attached to the substratum.

Langerhans cells in squamous exocervical carcinoma: a quantitative and ultrastructural study

The gross morphology, density, distribution, and ultrastructure of the Langerhans cell (LC) in the human exocervix in cases of cervical intraepithelial neoplasia (CIN) and incipient carcinoma were investigated. Two zinc-iodide-osmium (ZIO) procedures were applied to epithelial sheets and to tissue sections for light and electron microscopy. The ZIO methods as well as conventional electron microscopy revealed the presence of LCs in CIN, in the invasive prongs, and in the lymphoid infiltrate of the chorion. The epithelial sheets demonstrated a LC density 3.5 times higher than we have previously reported for the normal exocervix. The region around the external os displayed the highest LC density and the most advanced grades of CIN. The LCs were classified into six types according to the number of processes and secondary branches. The most ramified types were more abundant in the neoplastic exocervix than in the normal exocervix. The LC in all locations of the exocervix with carcinoma showed hypertrophy of the rough and smooth endoplasmic reticula and a large number of filaments. The RER displayed dilated cisternae containing electron-dense material. Specialized contacts between LCs and lymphocytes were an outstanding finding. These findings suggest that the LC might play an important role in the neoplastic process.

The exfoliating epithelial surface of the uterine cervix. IV: Scanning electron microscopical study in invasive squamous carcinoma of human subjects

The exfoliating epithelial surface of 15 invasive squamous carcinomas of the uterine cervix was investigated with the aid of the scanning electron microscope (SEM). At low magnification (less than or equal to 5,000 X) thirteen tumors presented irregular cobblestone-like structures and the remaining two, irregular intermediate formations (i.e. between cobblestones and mosaics). Cellular overlapping was found in three tumors. At higher magnifications (up to 25,000 X) all 15 tumors showed irregular disorganized structures such as bizarre microvilli with or without fragmented microrugae. Seven tumors had in addition tall finger-shaped protrusions and two rumors crater-like formations covered by irregular microvilli. The SEM structure found in invasive squamous carcinoma differed from the SEM structures earlier reported for the normal squamous or glandular epithelium, squamous metaplasia, dysplasia or carcinoma in situ of the uterine cervix.