Splenic vein originate from:
From the red pulp sinusoids, blood proceeds to the red pulp veins that joint together and enter the trabeculae, forming the trabecular veins. The splenic vein originates from these vessels and emerges from the hilum of the spleen. The trabecular veins do not have individual muscle walls; i.e. their walls of composed of trabecular tissue. They can be considered channels hollowed out in the trabecular connective tissue lined by endothelium. Ref: Mescher A.L. (2010). Chapter 14. The Immune System & Lymphoid Organs. In A.L. Mescher (Ed), Junqueira's Basic Histology: Text & Atlas, 12e.
Central aeries
White pulp aeries
Penicillar aerioles
Trabecular veins