ELECTRON MICROSCOPICAL OBSERVATIONS ON THE TRACHEAL EPITHELIUM OF THE ONE-HUMPED CAMEL (CAMELUS DROMEDARIUS) WITH SPECIAL REFERENCE TO CILIOGENESIS

This study was carried out on 10 adult, apparently healthy one-humped camels of different ages and of both sexes. The ultrastructure of camel tracheal epithelium was studied by scanning and transmission electron microscopes. Scanning electron microscopy revealed the presence of ciliated cells, goblet cells and occasionally non-ciliated microvilli covered cells. Four main cell types were observed with the transmission electron microscope: Ciliated, goblet, basal and intermediate cells, in addition to the migratory cells as well as the occasionally observed non ciliated microvilli covered cells. The latter cell type was observed in different stages of differentiation into ciliated cells i.e. undergo ciliogenesis. Ciliated cells were numerous, structurally similar to those of the other mammalian respiratory epithelial cells and contained prominent ciliary rootlets. Goblet cells contained secretory granules variable in number, size and electron density. Some cells contained electron-lucent granules occasionally with electron-dense core, others showed electron dense- granules with a light halo ring. These granules were discharged into the lumen of the trachea either by exocytosis or apocrine-like mode of secretion. Basal and intermediate cells were structurally similar, but the basal ones possessed numerous ribosomes and tonofilaments. Lymphocytes, plasma cells and polymorphonuclear leukocytes were also observed within the intercellular spaces of this epithelium.