Postnatal development of the spleen in Didelphis virginiana.

AUTOR(ES)

Cutts, J H

RESUMO

The postnatal development of the spleen has been examined in 85 opossums ranging in age from newborn to adult. At birth the spleen consists of a well vascularized mass of mesenchymal tissue and lacks lymphatic tissue or any evidence of haemopoietic activity. Haemopoiesis is evident at seven days, increases to a maximum at about two to three weeks and thereafter gradually declines. Although production of granulocytes has disappeared by 60 days postnatum, a small degree of erythropoiesis and megakaryocyte formation continues throughout life. Lymphatic tissue appears by the third week, but germinal centres do not appear until after weaning. A feature of the spleen during the first three to four days is the presence of a population of primitive 'blast' cells.

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