The American journal of anatomy . the mesial moietyof the interclavicular sac. The mesial moiety, however, as de-scribed below, usually has its origin from the third exceptional point of origin may account for the fact thatsome observers have ascribed the origin of the interclavicularsac to the second entobronchus while others have claimed thatit arises from the third entobronchus. The third entobronchus arises (fig. 28) somewhat more mesiallyon the intra-pulmonary bronchus than the first two. On thesecond half of the sixth day it extends dorsally a short distance, 486 WILLIA
The American journal of anatomy . the mesial moietyof the interclavicular sac. The mesial moiety, however, as de-scribed below, usually has its origin from the third exceptional point of origin may account for the fact thatsome observers have ascribed the origin of the interclavicularsac to the second entobronchus while others have claimed thatit arises from the third entobronchus. The third entobronchus arises (fig. 28) somewhat more mesiallyon the intra-pulmonary bronchus than the first two. On thesecond half of the sixth day it extends dorsally a short distance, 486 WILLIAM A. LOCY AND OLOF LARSELL then enlarges and bends caudally, descending on the mesial sideof the central lung tube so that the expanded distal end lies atthe side of the main bronchus, not above it, as is the case withentobronchi numbers 1, 2. Figures 30, 32 and 33 represent the beginning of a bud project-ing ventrally from the third entobronchus which is to play animportant part in the later history of the lung. This hollow bud. Fig. 38 Dorso-mesial view of right lung of an embiyo slightly younger thanthe one sketched in figures 34 to 37. Illustrates the exceptional position of ori-gin of the mesial moiety of the interclavicular air-sac, from the second instead ofthe third entobronchus. gives rise to two branches, one cephalad and the other more cephalad branch forms the mesial moiety of the inter-clavicular air-sac (figs. 33 34); the ventrad, bladder-like portion,differentiates into the anterior intermediate air-sac. By theclose of the eighth day of incubation both these air-sacs projectbeyond the boundary of the lung. It should be noted that under the exception indicated above,namely, when the second entobronchus gives rise to the mesial THE EMBRYOLOGY OF THE BIRDs LUNG 487 moiety of the interclavicular sac, the branch of the third ento-bronchus just described does not divide and produces only theanterior intermediate air-sac. The other division of the third ento
Size: 1321px × 1891px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorwi, bookcentury1900, bookdecade1910, booksubjectanatomy
