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Fig. 55. Schematic lateral view of dissection of four-day chick to show the body cavity and the more important mesenteries

When the ventral mesocardium, and a little later the dorsal mesocardium, breaks through, the primary right and left coelomic chambers become confluent to form the pericardial region of the body cavity (Figs. 24 and 55). Later in development the ventral mesentery farther caudally disappears so that caudally as well as cephahcally an unpaired condition of the coelom is brought about (Fig. 54, H). In the liver region the ventral mesentery does not disappear. The liver arises as an outgrowth from the gut and in its development extends into the ventral mesentery (Fig. 54, G). The portion of the ventral mesentery dorsal to the liver persists as the gastro-hepatic omentum, and the portion ventral to the liver persists as its ventral ligament (falciform ligament) (Fig. 55)

The primary dorsal mesentery persists and forms the supporting membranes of the digestive tube. In the adult its different regions are named according to the parts of the digestive tube with which they are associated, as for example, mesogaster that part of the primary dorsal mesentery which suspends the stomach, mesocolon, that part of the primary dorsal mesentery supporting the colon, etc.

The separation of the body cavity into pericardial, pleural, and peritoneal chambers is accomplished by the formation of septa growing in from the body wall. Consideration of the details of their formation would lead us into stages of development beyond the scope of this book. Those interested in following the later embryology of the chick will find in the appendix references to more exhaustive books, and to a few of the more recent original papers on its development.

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Pages where the terms "Historic Textbook" and "Historic Embryology" appear on this site, 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 interpretation of developmental mechanisms reflect the understanding at the time of original publication and those of the preceding periods, these interpretations may not reflect our current scientific understanding. (More? Embryology History)

Reference

Patten, B.M. (1920). The Early Embryology of the Chick. Philadelphia: P. Blakiston's Son and Co.

The Early Embryology of the Chick: Introduction | Gametes and Fertilization | Segmentation | Entoderm | Primitive Streak and Mesoderm | Primitive Streak to Somites | 24 Hours | 24 to 33 Hours | 33 to 39 Hours | 40 to 50 Hours | Extra-embryonic Membranes | 50 to 55 Hours | Day 3 to 4 | References