Function: barrier, flood exchange, lubrication, transepithelial transport.
Location: lining body cavities (thoracic, pericardial, abdominal), Bowman's capsule (kidney).
Origin: mesoderm: splanchnotom
Location: lining vascular system.
Origin: mesenchyme
Function: barrier, absorption.
Location: ovary, kidney tubules (distal and proximal thick segments)
Origin: mesoderm
Function: barrier, absorption, and secretion.
Location: lining of stomach, small intestine and colon, gallbladder.
Origin: endoderm
Function: secretion, conduit.
Location: trachea and bronchi, deferens, efferent ductules of epididymis.
Origin: endoderm, mesoderm.