File:Buell-plate02.jpg

Origin of the Pulmonary Vessels in the Chick - Plate 2

Fig. 7

From an injected embryo of 35 somites, 55 hours' incubation, dissected by the paraffin method. The lung consists of a simple ventral diverticulum beginning to show lateral swellings into right and left primary buds. The common pulmonary vein opens into the sinus at the level of the lung rudiment. It drains the capillaries of both cephalic and post-caval portions of the splanchnic plexus. The anastomoses between the plexus and the cardinal veins are established. The pulmonary arches are not formed, although the dorsal and ventral primordia of the arch are indicated by the blind pouches. The cranial end of the pulmonary artery is now easily recognized in the capillary plexus.

Fig. 8

A 36-somite chick of 60 hours' incubation, injected with ink and dissected by the paraffin method. Only the right half of the vascular tree is shown. This stage is but slightly older than that in figure 7. The, pulmonary arch is now complete but still retains a capillary appearance. The pulmonary artery can be recognized in the cephalic portion of the plexus. The right lobar tributary of the common vein is formed and is connected with its corresponding artery on the dorsal surface of the lung-bud. The cranial tributary of the common vein is plainly seen. The wall of the sinus venosus has been removed to show the opening of the common pulmonary vein into the sinus.

Figs. 9-10

Dissections of injected chick embryos of 85 hours' incubation. Figure 9 shows the right side of the pulmonary system. In figure 10 the spinal cord, dorsal aorta, and dorsal surface of the gut have been removed, exposing the pulmonary system in a coronal plane from a dorsal view. The lung is in a simple stage of right and left primary buds which do not show further lobulation. The left bud is more ventral than the right and is parallel to the gut. The right bud tends more toward a horizontal position in relation to the plane of the gut. The pulmonary vessels bear a constant relation to the bronchi of the buds, even at this early stage. The artery lies dorsal and lateral to the bronchus; the vein, ventral and medial to the bronchus, the lung capillaries lying between the two on the dorsal surface of the buds. The pulmonary artery comes off from the arch at the junction of its middle and proximal third, and passes directly back to the tip of the lung-bud, where it joins freely, in a capillary net, with the corresponding tributary of the pulmonary vein. Very near the arch a capillary connection is given off to the anterior cardinal vein. The two arteries extend parallel to each other and in their proximal third are joined by numerous capillary anastomoses which are drained by the cranial tributary of the common vein. The middle third of the artery has no branches. The entire distal third is connected with the vein by a rich plexus of capillaries over the dorsal surface of the lung-bud. A few twigs are still present, connecting with the post-caval portion of the plexus. The pulmonary vein is made up of several tributaries which unite in a common trunk; this in turn empties into the sinus venosus. Considerable variation is encountered in the pattern of these branches in different specimens. The right and left lobar branches to the lung-buds drain their respective arteries. In figure 9 a vessel connects the right lobar vein to the cranial tributary. This is not constant and is absent in figure 10. A few small branches to the post-caval plexus are seen caudal to the lobar branches. The cranial tributary of the common vein drains the anastomotic vessels between the two pulmonary arteries and arches. It extends directly caudad on the ventral surface of the gut and, with the other tributaries, empties into the common vein. It may have but one opening into the common vein, as in figure 10. This stage is about the oldest in which the cranial tributary is seen complete and represents its highest development. In a later stage, as described by Squier, the cranial tributary loses its arterial connections and disappears. The pulmonary arches (sixth) have undergone rapid growth and have included the arteries within their walls.

1922 Chicken Pulmonary: Fig 1 | Fig 2 | Fig 3 | Fig 4 | Fig 5 | Fig 6 | Fig 7 | Fig 8 | Fig 9 | Fig 10 | Plate 1 | Plate 2 | Carnegie No.66 | Chicken Development | Respiratory

Links: Carnegie Institution of Washington - Contributions to Embryology | Chicken Development | Respiratory System Development

Historic Disclaimer - information about historic embryology pages

Pages where the terms "Historic" (textbooks, papers, people, recommendations) appear on this site, and sections within pages where this disclaimer appears, indicate that the content and scientific understanding are specific to the time of publication. This means that while some scientific descriptions are still accurate, the terminology and interpretation of the developmental mechanisms reflect the understanding at the time of original publication and those of the preceding periods, these terms, interpretations and recommendations may not reflect our current scientific understanding.     (More? Embryology History | Historic Embryology Papers)