Morphological variations and population density of membrane-coating granules in human gingival sulcular epithelium

Smokeless tobacco-induced lamellar body abnormalities

OBJECTIVES

To compare the morphological changes and quantitative distribution of lamellar bodies (Lb) (membrane coating granules) in the hamster cheek pouch epithelium with smokeless tobacco (ST).

MATERIALS AND METHODS

Archives of experimental material from previously published studies [S. Ashrafi, A. Das, R. Worawongvasu, B. Mehdinejad and J. Waterhouse (1992) Scanning Microscopy6: 183] were utilized. Animals in experimental group received most ST (snuff) in their right pouch, 5 days weekly, for 24 months, while no snuff was given to control group. After 24 months, the epithelial tissues were processed for electron microscopic study. Volume densities of Lb were assessed by morphometry.

MAIN OUTCOME MEASURES

Densities of Lb in the two groups, experimental vs control.

RESULTS

In the control, Lb extruded their contents into the intercellular spaces of upper granular layers and in between the last granular cell layers and keratin layers to form a permeability barrier. Conversely, in the smokeless tobacco-treated epithelium, the majority of the Lb that were formed remained inside and accumulated within the granular cells, without extruding their contents into the intercellular spaces to form a lipid compound permeability barrier.

CONCLUSIONS

Commercial alkaline ST may have contributed to the abnormal accumulation of Lb in the granular cell layer and affected the extrusion process of Lb to form an incomplete permeability barrier in the oral epithelium.

Membrane-coating granules and the intercellular cementing substance (membrane-coating material) in the epidermis in different regions of the equine hoof

This study aimed to carry out a comprehensive morphological examination of the structure and ultrastructure of the membrane-coating granules (MCG) and membrane-coating material (MCM) common to all hoof segments as well as segment-specific features in the MCG and MCM regarding their synthesis, structure and biochemical composition. Tissue samples from the hooves of the left front and right hind limb of 20 adult riding horses were used. Samples were preserved and embedded for histological routine methods as well as for histochemical techniques and tracer techniques for light and electron microscopy. The MCM shows a segment-specific structure, biochemical composition and function, which were demonstrated for the different parts of the hoof. The MCM and its properties are related to the segment-specific horn quality. Besides intercellular structural factors the MCM is of major importance for the structural integrity and the biomechanical properties of the hoof horn. The physiological structure and composition of MCM provides explanation for the existence of clinically well-known sites of predilection for hoof disorders such as the White Line Disease. Alterations of the MCM play a role in dysfunction and diseases of the hoof epidermis; they are particularly involved in the pathogenesis of infectious diseases of the hoof.

[Morphology of the marginal lingual papillae in newborn piglets]

The morphology of the marginal lingual papillae in eight newborn pigs aged 1-5 days was examined at the light-microscopical level, as well as, for the first time, using electron transmission and scanning methods. The papillae marginales are arranged tuft-like or rosetted with chief and accessory papillae, the individual papillae varying considerably in shape. Leaf-, tongue- or fingerlike and conical shapes predominate. The stratified squamous epithelium is either keratinized, resembling the epidermal differentiation pathway, or non-keratinized, according to the mucosal pathway. The characteristic morphology of keratinocyte differentiation is shown with special reference to the establishment of the permeability barrier. The connective tissue papillae are intensively surface-enlarged by means of multiple fingerlike protrusions.