Vascular Arrangement of the Mammalian Spleen as Revealed by Injection Replica Scanning Electron Microscopy

The three-dimensional vascular arrangement of the mammalian spleen was investigated by means of injection replica scanning electron microscopy.

The vascular arrangement of the white pulp and marginal zone in the mammalian spleen was divided into two groups: (1) the rat and mouse type, and (2) the human and dog type. In the rat and mouse, (a) the central artery gave rise to numerous follicular capillaries which usually terminated in the inner side of the marginal zone, (b) the follicular capillaries showed a small network in the germinal center, (c) the follicular capillaries occasionally entered into the marginal zone and terminated in the intercellular space, and (d) some of the penicillar arteries showed a centripetal course and enter into the white pulp to open into the marginal zone. In the human and dog, (a) follicular arteries gave off many arterial capillaries in the marginal zone shortly after penetration of the marginal zone, (b) recurrent branches of the penicillar artery entered into the marginal zone, (c) some of the recurrent branches entered into the follicle and supplied the follicular capillaries, (d) follicular capillaries orginated from vessels distributed in the marginal zone, recurrent branches of the penicillar arteries and follicular arteries, (e) the main sources of the follicular capillaries were from the vessels in the marginal zone, and (f) the follicular capillaries were chiefly distributed in the germinal center.

The terminal end of the penicillar artery in the pulp cord was mostly open type in the mammalian spleen.