Splanchnopleure vs. Somatopleure

I) Definitions

The vertebrate body can be divided into two tubes. These tubes are separated from each other by a space (cavity) -- the coelom. The coelom is formed when lateral plate mesoderm splits. The result is the formation of:

A) Splanchnopleure (derived from Greek splanchno = the viscera; pleur = the side). It is composed of the mesoderm internal to the coelomplus the endoderm. This is the inner tube, the side towards the viscera ("guts").

B) Somatopleure (derived from Greek soma = body; pleur = the side). It is composed of the mesoderm external to the coelom plus theectoderm. This is the outer tube, the side towards the body.

II) Components

 The splanchnopleure and somatopleure are each composed of different structures (derived from different germ layers). The components of each are as follows:

A) The splanchnopleure is composed of the following components:

1) The viscera (guts) including all their parts derived from endoderm and mesoderm. This includes the digestive system and its outgrowths (e.g., lungs).

2) The visceral peritoneum, visceral pleura and visceral pericardium (the inner lining of the coelom that covers the viscera; it is derived from lateral plate mesoderm).

B) The somatopleure is composed of the following components:

1) The body wall including all the parts derived from mesoderm (e.g., somatic muscles, somatic skeleton, kidneys) as well as the ectoderm (skin).

2) The parietal peritoneum, parietal pleura and parietal pericardium (the outer lining of the coelom that covers the body wall; it is derived from lateral plate mesoderm).