Morphogenesis of the ostrich (Struthio camelus) trachea and lung in different embryonic and fetal stages

The ostrich (Struthio camelus) is an important wild species highlighted in national and international livestock industry. This research was conducted to analyze the development of the ostrich respiratory system during fetal and embryonic stages. A total of 50 fertile ostrich eggs were collected from commercial farms and then incubated at 36.00 - 37.00 ˚C and 25.00 ± 2.00% humidity for 40 days. Sections were taken on days 13, 22, 26, 30, 36, and 42 of incubation from the lung and the cranial, middle, and caudal parts of the neck after decapitation of ostrich embryos and blood drainage. After fixation, processing, blocking, and sectioning, all samples were stained by Hematoxylin and Eosin, Alcian Blue (AB), Van Gieson, and Periodic acid-Schiff (PAS) techniques. It was concluded that the trachea in the 13-day-old embryo and goblet cells (PAS-positive and AB-positive) had incomplete rings of hyaline cartilage and differentiation of mesenchymal to the loose connective tissue. The bronchial stage of the lung was observed in the 22-day-old embryo, pseudoglandular stage in the 26-day-old embryo, and parabrachial and air capillary stage in the 30-day-old embryo. The information obtained from this study will be useful for diagnosing pathologies affecting this vital system and results in improving industrial breeding management.