Red pulp arterial terminals in congestive splenomegaly. A morphometric study.

A quantitative analysis of the red pulp arterial terminals (comprising arterioles = penicilli, arterial capillaries and sheathed capillaries) has been carried out in congestive splenomegaly occurring in active chronic hepatitis, hepatic cirrhosis and idiopathic portal hypertension. Comparisons have been made with control spleens surgically removed for accidental trauma. Red pulp volume enlargement appears to be associated with a progressive lengthening of arterial terminals, which present a length density similar to that of normal spleens. Moreover, a different rearrangement of the various components of the arterial tree is present: in particular, the percent and absolute volumes of arterioles and arterial capillaries show a higher increase than those of sheathed capillaries. The present study points out the involvement of arterial terminals in the pathological rearrangement of the red pulp in congestive spleens, so supporting the hypothesis that splenomegaly does not result simply from passive congestion.