Three-dimensional architecture of the keratin filaments in epithelial cells surrounding taste buds in the bat circumvallate papilla

The three-dimensional architectures of the perigemmal cells and their kerat in bundles in the rat circumvallate papillae were studied by transmission a nd scanning electron microscopy, The perigemmal cells were classified into three layers: basal, middle and upper. The basal layer consisted of polygon al cells located close to the basal lamina, the middle layer comprised long itudinally elongated cells fitting the lateral convexity of the taste bud, and the upper layer was imbricating hat cells along the upper portion of th e taste bud. When fresh specimens were jointly treated with Triton X-100 an d sonication, the taste buds were often detached and the cytoplasmic matric es of the perigemmal cells were effectively removed. Consequently, we were able to demonstrate an extensive network of the subplasmalemmal keratin bun dles of the perigemmal cells. The framework appeared either as a thin lacew ork, a thick fence-like structure, or a lattice work in the basal, middle, and upper layers, respectively. The thin lacework in the basal layer was co nsidered to be a developing process of the framework. The thick fence-like structure in the middle layer probably plays a primary role in supporting t he taste bud. The latticework in the upper layer is believed to reflect a r emodeling in reducing the keratin framework.