Ultrastructure of spontaneous vaginal keratinization in hanging-drop organ culture (Balb/cCrgl MICE)

Ultrastructural features of vagina at different phases of the oestrous cycle in the female African giant rat (Cricetomys gambianus Waterhouse)

The ultrastructures of the vagina at various stages of the oestrous cycle in female African giant rats (Cricetomys gambianus Waterhouse) were described in the present study. At mid-proestrus, late proestrus (LP)/early estrus (EE) and mid-estrus (ME) as well as late metestrus (LM)/early diestrus (ED) and mid-diestrus (MD), complex interface of epithelium and lamina propria were observed. Cells of the stratum basale formed finger-like extensions into the underlying lamina propria and tips of the extensions displayed hemidesmosome while basal lamina followed the contour of the extensions. At mid-metestrus (MM) and late diestrus/early proestrus, well developed, relatively straight basal lamina interfaced between the stratum basale and the lamina propria without finger-like projections. Polygonal cells with indented nuclei and, cytoplasm containing ribosomes, polysomes, intermediate filaments, and mitochondria were observed in stratum spinosum at all the phases of the oestrus cycle. At MM, LM/ED, and MD, the stratum spinosum had numerous desmosomes with tonofilaments, large microvilli that intermingled at the intercellular spaces and evidence of trapped/migrating neutrophils and lymphocytes. The superficial layer displayed short microvilli at mid-proestrus, cornification at LP/EE and desquamation at ME while it showed condensation of intermediate filaments; projections of large microvilli into the luminal surface at MM, and embeddement of neutrophils at LM/ED as well as MD. This study looked into the reproductive biology of female African giant rats to produce baseline information on its reproductive organs and represented the first comprehensive description of the vagina at the ultrastructural level during oestrous cycle.

Clear and dark basal keratinocytes in human epidermis. A stereologic study

Standardized techniques of stereologic cytology were applied to normal human epidermis, in order to comparatively describe the suprabasal and the dark and clear basal keratinocytes. The results, expressed mainly in surface and volume densities of epidermal components, showed that some important stereologic parameters of dark basal keratinocyte constituents exhibited values which could be interpreted as intermediate between those of the clear basal keratinocytes and those of the suprabasal keratinocytes. Although the degenerative nature of dark cells cannot be ruled out, the stereologic characterization of their cell architecture also could indicate that dark basal cells are already differentiating keratinocytes still remaining in the basal layer.