Splenic architecture reflected in the connective tissue structure of the human spleen

An analysis of the connective-tissue structure of the human spleen can give us information about the basic architecture of the organ. The most important part of the spleen is the lienic center around which the subcapsular zone forms an envelope, like a mantle. This zone has but little depth and develops superficially. The tangential radial beam net ('Tangentialbalkennetz') is formed partly by the radial trabeculae of the capsule and partly by the outer branches of the arbor trabecularis. This arbor divides into 5-6 branching orders. The branches of orders 1 to 3 surround the parenchyma of the spleen center's inner layer. The lienic lobuli which are found between the branches are relatively large and are connected very extensively with their parenchyma. The branches of orders 4, 5, and 6 enclose the lienic lobuli of the outer layer of the spleen center. The splenic lobuli are defined by the vascular course. Mostly they are provided with one or two arterial influxes and, as a rule, with only one venous drain. Their mutual delimitation is more of a functional than of a morphological nature. This led von Herrath to coin the term 'functional spleen lobuli'. The lienic envelope lies between the inside of the capsule and the outermost branchings of the arbor trabecularis. This arbor is subdivided, by the radial trabeculae, which never have any vessels, into elongated lobuli and serves first and foremost to regulate pressure. The lattice fibers are of high tensile strength and are extensions of the collagenous fibers seen at the microscopic level.