A scanning electron microscopic study of rete ridges in the cheek pouch of normal young, adult and aged Syrian hamsters

Abstract

Cheek pouches were removed from BIO 87.20 male hamsters 4 weeks, 8 months or 18 months of age. One pouch from each animal was routinely processed for light microscopy. The epithelium and connective tissue of the remaining pouches were separated with EDTA and routinely processed for scanning electron microscopy. Two types of rete ridge were found: simple, consisting of a single epithelial ridge or blunt projection and complex, made up of multiple interconnecting ridges. The simple type predominated at 4 weeks (90%) but the complex type predominated at 8 (58%) and 18 months (73%). Although the 8- and 18-month pouches were significantly larger than the 4-week ones, the total number of rete ridges was similar at all ages. This, taken in association with the shift in type with age, suggests that the simple rete ridges develop into the complex ones. With increasing age more of the complex rete ridges took on the characteristics of touch domes. These changes in the shape of the rete ridges with age need to be taken into account in studies on experimentally altered cheek pouches so that they are not mistaken as pathological changes.