Abstract
Abstract: :
Purpose: The aim of our study is a detailed morphological and immunocytochemical description of snake-like chromatin (SLC) structures to elucidate the mechanisms by which SLC arises in cells of the human conjunctiva. Methods: To collect specimens for impression cytology of the conjunctiva (upper and lower bulbar) nitroacetate filters and Millicel membranes were used. Ten normal controls (SLC-negative cells) and 15 specimens from dry eyes (with more than 1000 SLC cells) were evaluated after Papanicolaou-Gills staining by light microscopy. The number of micronuclei-like structures (MN) was evaluated as a marker of nuclear division. The nucleolar proteins fibrilarin, B 23, cell-cycle proteins PCNA and Ki 67 were detected by immunocytochemistry. Results: Light microscopy. SLC epithelial cells were observed as clusters ranging in size from a few cells to more than 50% of all cells. SLC cells often showed membrane notching, cuff constricted SLC structures and binucleate forms. The number of micronuclei-like structures in control epithelial cells was 1.33 MN/1000 cells (±0.52). Cells with SLC were not observed in any of these specimens. Micronucleation in epithelial cells with SLC reached 22.07 MN/1000 cells (±12.48). The number of micronuclei-like structures in SLC-negative cells in the same (pathological) specimens was 3.47 MN/1000 cells (± 3.94). Immunocytochemistry. Fibrilarin in normal cells was characterized by two to five randomly distributed spot pattern in the nucleus. In SLC positive nuclei mostly two centralized spots and diminished signal were observed in equatorial level in the space between a SLC structure and the nuclear lamina. Fourth percent of cells from control and 20% of cells from pathological specimens were positive for B 23 antigen. Cells with SLC structures were always negative for B 23. Ki 67. PCNA positivity was detected in islands of control cells but not in SLC positive cells. Conclusions: The high level of micronuclei-like structures in SLC cells, without presence of characteristic mitotic markers but with an abnormal nucleus with membrane notching and binucleated SLC forms, leads to the conclusion that the phenomenon of snake-like chromatin is a special type of nuclear/cell division (but not mitosis) similar to amitosis.
Keywords: conjunctiva • microscopy: light/fluorescence/immunohistochem