RESUMO
The putative respiratory epithelium lining of the bronchial tree of 20-60 mm crown-rump length [CRL] camel fetuses displayed the staggered nuclear organization characteristic of single cilium on their apical surfaces. The bronchial epithelium revealed a clear evidence of ciliogenesis, which occurred as early as 70 mm CRL, starting in the main bronchi and gradually proceeding distally, along the developing bronchial tree. The ciliogenic cells were gradually increased with gestational age. in fetuses of 70-370 mm CRL, the bronchial epithelium displayed a myriad of disintegrating sloughed apoptotic cells intermingled with ciliated and ciliogenic cells together with few non-ciliated microvillus types. Mitochondrial swelling, dilatation of the rough endoplasmic reticulum, vacuolation of the of the cytoplasm, distortion of the intercellular junctions, together with clumping of the nuclear chromatin were the early signs of cellular apoptosis. With time, the regressing apoptotic cells tended to detach themselves from their neighbors and underlying basement membrane moved upwards and sloughed into the airway lumen. These morphological alterations, concerning the disintegrating sloughed apoptotic cells, were first observed in the main bronchi and gradually proceeded by age towards the bronchiolar branches. In adult camels the bronchial epithelium was formed mainly of ciliated and non-ciliated microvillus cells; however, that at term of gestation was composed of ciliated cells, non-ciliated microvillus cells; however, that at term of gestation was composed of ciliated cells, non-ciliated microvillus types together with some cells possessing surface microplicae