What is the embryonic origin of the spleen?

The spleen develops from mesoderm in the dorsal mesogastrium, which is a mesentery related to the stomach. It forms from mesenchymal condensations that fuse into a single mass.

How does the spleen form during development?

During development, mesenchymal cells condense to form small nodules called splenic lobules (or spleniculi). These fuse together to create a single splenic mass that projects into the left side of the dorsal mesogastrium.

What ligaments are formed during spleen development?

The development of the spleen divides the dorsal mesogastrium into two ligaments: the gastrosplenic ligament, which connects the spleen to the stomach, and the lienorenal (splenorenal) ligament, which connects the spleen to the left kidney.

What tissues in the spleen come from mesoderm?

All spleen tissues originate from mesoderm, including the capsule, septa, and reticular stroma from mesenchymal connective tissue, and lymphoid tissue from free mesenchymal cells that become lymphoblasts and hemopoietic cells.

When does hematopoiesis occur in the spleen?

Hematopoiesis in the spleen begins early in embryonic life and continues throughout fetal development. It stops after birth, but lymphocyte production persists postnatally.

What are accessory spleens, and where can they be found?

Accessory spleens (spleniculi) are small additional spleens that may be located near the hilum, along the splenic artery, in the tail of the pancreas, or in other areas like the greater omentum. They can become hypertrophic after splenectomy and cause symptom recurrence.

What is a lobulated spleen, and how does it develop?

A lobulated spleen results from the persistence of fetal lobulation during development. The splenic notches along its superior border are remnants of this developmental origin.

Spleen Development – Mesodermal Origin

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