title: Development of respiratory rhythms in perinatal chick embryos.
abstract: In chick embryos, gas exchange takes place via the chorioallantoic membrane (CAM) and the lungs at approximately 1 day prior to hatching. The present study was designed to elucidate the development of respiratory rhythms in the chick embryo during the whole pipping (perinatal) period with a condenser-microphone measuring system. The microphone was hermetically attached on the eggshell over the air cell on day 18 of incubation. It first detected a cardiogenic signal (i.e. acoustocardiogram), and then beak clapping and breathing signals (acoustorespirogram, ARG). The first signals of lung ventilation appeared intermittently and irregularly approximately once per 5 s among the clapping signals after the embryo penetrated its beak into the air cell (internal pipping, IP). The respiratory rhythm then developed irregularly, with a subsequent more regular rate. The envelope pattern of breathing from the onset of IP through external pipping (EP) to hatching was constructed by a specially devised procedure, which eliminated external and internal noises. The envelope patterns indicated that the IP, EP and whole perinatal periods of 10 embryos were 14.1+/-6.4 (S.D.), 13.6+/-4.0 and 27.6+/-5.4 h, respectively. In addition, they also indicated the period of embryonic hatching activity (i.e. climax) which was 48+/-19 min. The development of respiratory rhythm was also shown by the instantaneous respiratory rate (IRR) which was designated as an inverse value of two adjacent ARG waves.
authors.affiliation: Department of Electrical and Electronic Engineering, Muroran Institute of Technology, 050-8585, Muroran, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Chiba
authors.forename: A H
authors.initials: AH
authors.lastname: Khandoker
authors.forename: M
authors.initials: M
authors.lastname: Nobuta
authors.forename: K
authors.initials: K
authors.lastname: Moriya
authors.forename: R
authors.initials: R
authors.lastname: Akiyama
authors.forename: H
authors.initials: H
authors.lastname: Tazawa
mesh_terms: D000818:Animals; D002642:Chick Embryo; D004625:Embryo, Nonmammalian / Q000502:physiology*; D047108:Embryonic Development; D012119:Respiration