Question

What is Dorsal Mesogastrium

Answer 1

As mentioned earlier, originally this mesentery also lies in the median plane, extending from the greater cur­vature of the stomach to the posterior abdominal wall. Isolated spaces in the form of clefts and, vacuoles appear in the dorsal mesogastrium near its at­tachment to the posterior abdominal wall. These spaces soon enlarge and merge together, resulting in creation of a larger cavity in the right half of the dorsal mesogastrium. This cavity es­tablishes continuity with the peritoneal cavity and extends progressively into the mesentery. This space is the primi­tive omental bursa (lesser peritoneal sac). Definitive shape and position of the omental bursa is intimately related to the developmental changes in the position of stomach.
In the 5th week of development, primordium of the spleen appears as a swelling produced by the proliferation of mesenchymal cells between the two layers of the dorsal mesogastrium. Rotation of the stomach around the longitudinal axis pulls the dorsal mesogastrium to the left, resulting in enlargement of the omental bursa which soon expands transversely and cranially and comes to lie between the stomach and the posterior abdominal wall. With the formation of the omental bursa, a portion of the dorsal meso­gastrium lying between the spleen and dorsal midline fuses with the posterior abdominal wall. The remaining portion (which does not fuse with the abdo­minal wall) connects the spleen to the
abdominal wall in the region of left kid­ney and is called lienorenal ligament. That part of the dorsal mesogastrium which extends from the spleen to the stomach is known as gastrolienal (or gastrosplenic) ligament.
After the rotation of the stomach is complete, the dorsal meso­gastrium continues to grow in a down­ward direction. This elongation of the dorsal mesogastrium results in the for­mation of a double- leaved apron called greater omentum (each leaf of this apron consists of two layers of peri­toneum). The greater omentum ex­tends in front of the transverse colon and loops of the small intestine. The leaves of the greater omentum fuse to form a single sheet that hangs from the greater curvature of the stomach. The upper part of the posterior leaf of the greater omentum also fuses with the mesentery of the transverse colon.