Splenectomy of the fetal lamb early in development as a model for congenital asplenia

Background: The liability to overwhelming infection of children lacking a s pleen either as a result of its congenital absence or because of splenectom y, has been frequently documented. Although there have been numerous studie s of the consequences of experimental splenectomy in postnatal animals, thi s is the first study of the effects of this operation in early fetal life. Methods: A technique is described for microsurgical removal of the spleen f rom fetal lambs approximately one-third of the way through gestation, when the fetus is approximately the size of a mouse. Lambs that had been splenec tomized in utero were submitted to haematological examination in postnatal life and were challenged with pneumococcal polysaccharide to test their imm unological competence. Results: Lambs in which splenectomy had been performed close to the gestati onal age of initiation of the splenic contribution to differentiation of im mune and haemopoietic systems, exhibited insignificant deviations from norm ality in postnatal life. Conclusion: Provided the spleen is removed from the fetal lamb sufficiently early in gestation, it is possible for other lymphoid tissues to compensat e for most of the deficiencies that would be anticipated in animals lacking a spleen. In this experiment, splenectomy was performed at approximately t he developmental stage equivalent to that at which the spontaneous interrup tion of development that leads to human congenital asplenia occurs. The abs ence of major postnatal abnormalities observed in these lambs reinforces th e significance of the associated abnormalities in the development of the cl inical deficits observed in children with spontaneous asplenia.