Comparative study on respiratory and circulatory functions in avian eggs

点击翻译按钮获取中文摘要

1. Developmental patterns of embryonic heart rate (HR) in chickens were determined by impedance-cardiography during day 3-9 of incubation without impeding gas exchange through the eggshell. Additionally, responses of embryonic HR to 10% O_2 and 100% O_2 exponsoures were investigated. In contrast to the marked developmental changes in hypoxic sensitivity of HR,the HR showed little response to hyperoxia, suggesting no hypoxic drive to HR.2. Developmental patterns of HR in ostrich embryos were determined noninvasively by acoustocardiogram (ACG) in relation to eggshell gas conductance (G) and egg mass. They were not related to egg mass. However, embryos of high G eggs had high HR compared with those of low and medium G eggs, despite that they were incubated in a high humidity incubator to maintain adequate water loss from the eggs. Additional experiments mad one year later elucidated that the incubator humidity affected the HR of embryos developming in high G eggs.3. Developmental patterns of HR in emu embryos were also determined by ACG during the last 15 days of artificial incubation. The averaged pattern in 6 embryos was kept at about 170 bpm during the first 5 days of measurement and decreased to about 140 bpm during the remaining 10 days. The ACG could be detected during the assisted external pipping period.4. The allometric relations of embryonic HR with fresh egg mass were determined in precocial (N=9) and altricial and semi-altricial birds (N=20) . The allometric relation of HR at 80% of incubation period in precocial birds was similar to that of maximum HR (i.e., internal or external HR) in altricial birds.5. International symposium on cardiac rhythms in animals was held in Muroran Institute of Technology having 22 overseas participants including two collaborators (Prof. Ar and Prof. Burggren) to conclude and promote further the international scientific research.