STRUCTURE OF HAMSTER PALATAL GINGIVA AND INTERMOLAR MUCOSA AFTER INTRAPERITONEAL DOSING WITH N-METHYL-N-NITROSOUREA - A SCANNING ELECTRON-MICROSCOPE STUDY
Gc. Symes et al., STRUCTURE OF HAMSTER PALATAL GINGIVA AND INTERMOLAR MUCOSA AFTER INTRAPERITONEAL DOSING WITH N-METHYL-N-NITROSOUREA - A SCANNING ELECTRON-MICROSCOPE STUDY, Journal of Comparative Pathology, 112(4), 1995, pp. 403-415
The palatal gingiva and intermolar mucosa from normal hamsters and fro
m hamsters that had received N-methyl-N-nitrosourea (NMU) intraperiton
eally were examined by scanning electron microscopy over a 22-week per
iod. The normal gingiva and rostral two-thirds of the intermolar mucos
a were covered by flat polygonal cells that had a regular honeycomb su
rface pattern of interconnecting micro-ridges, distinct cell boundarie
s and imprints of cells that had been desquamated. The caudal third of
the intermolar mucosa in normal and NMU-treated hamsters was covered
by soft-palate type mucosa whose smooth surfaced cells surrounded scat
tered fungiform-like papillae. In NMU-treated hamsters changes were mo
re common in the rostral two-thirds of the intermolar mucosa than in t
he gingiva. At 10 weeks there were sessile and conical surface project
ions and saucer-shaped and conical epithelial-lined depressions. At 16
weeks these projections and depressions were larger and more numerous
, and groups of conical projections formed papillomatous-like lesions.
At 22 weeks the projections and depressions were further increased in
number and size and there were distinct papillomas. At 10 and 16 week
s the entire epithelium showed cells, cell boundaries and cell imprint
s resembling those in the controls, except that there were defects or
dilated intercellular spaces at the base of the conical depressions an
d some of the cells were thicker. Much of the 22-week epithelia had a
similar structure, but in some areas that did not show the projections
or depressions the cells varied in size and shape and were covered by
elongated micro-ridges. Here the surface was irregular as were the ce
ll boundaries. Examination of sections by light microscopy, both from
these irregular areas and from areas that appeared normal by scanning
electron microscopy, revealed that the deeper epithelial strata could
be either normal, dysplastic or at times malignant. However, scanning
electron microscopy failed to reveal dysplastic or malignant epitheliu
m.