WebJan 8, 2024 · The sternal vertebrae are fused in birds to form the keel. The keel has a midline ridge which divides the pectoral muscles into right and left sides. The ridge may be a deep structure, as is seen in pigeons, … WebAir sac. Air sacs are spaces within an organism where there is the constant presence of air. Among modern animals, birds possess the most air sacs (9–11), with their extinct dinosaurian relatives showing a great increase [clarification needed] in the pneumatization (presence of air) in their bones. [1] Theropods, like Aerosteon, have many air ...
The Harderian Gland in Birds: Histology and …
WebThe spleen is a principal organ of systemic immunity, and its importance in disease resistance is presumably accentuated by the scarcity of avian lymph nodes. The striking intraspecific variation in size partly reflects seasonal changes in spleen morphology and activity. Several explanations, principally based on changing oxygen demand, have ... WebBirds must be capable of high rates of gas exchange because their oxygen consumption at rest is higher than that of all other vertebrates, including mammals, and it increases many times during flight. The gas volume of the bird lung is small compared with that of mammals, but the lung is connected to voluminous air sacs by a series of tubes, making the total … green bay packers kansas city chiefs
A histological survey of avian post-natal skeletal ontogeny
WebOct 5, 2015 · Birds are one of the most recognizable and diverse groups of modern vertebrates. Over the past two decades, a wealth of new fossil discoveries and … WebDec 31, 2011 · Prolactin in birds often exerts an antigonadal influence (e.g., Bates et al., 1935; Nalbandov, 1945; Bailey , 1950; Bar, 2006 ) that is thought to play an important role in the WebNov 18, 2024 · Bone histology of crown-group birds is a research topic of great interest, permitting insight into the evolution of remarkably high growth rates in this clade and … flower shops in cheyenne wyoming