Mast cells, elastic fibres and the lamina propria in the hard palate of the rat.

The hard palate tissue of four adult Sprague-Dawley rats was serially sectioned para-sagitally and coronally. Stains for collagen, elastic fibres, non-sulphated and sulphated GAG were used. The collagen fibre component of the lamina propria revealed a well ordered structure which in the ante-molar rugae (AMR) split to enclose a core, but in the inter-molar rugae (IMR) passed under the core. Elastic fibres were liberally distributed in the cores of the AMR, running mainly antero-posteriorly but much sparser in the IMR. Mast cells and GAG were identified by means of the alcian blue pH 2.5 stain and after mapping them through a microscope tracing tube and quantifying the distribution in AMR no 2, three zones of distribution were observed. The core was the least populated zone and a possible connection with the GAG content is suggested. The fibre and GAG constituents of the AMR suggested that they are structural elements aimed at resisting the demands of function.