Invited Editorial Comment: Lessons From Conjoined Twins

summary, detailed study of SCT offers the promise of several new insights into normal embryological processes as well as clues to possible mechanisms of midline malformations in singletons. It is important to continue to document detailed anatomic descriptions of such fetuses, as in the cases of Pavone et al [1987]. In this way, new hypotheses can be formulated and tested. REFERENCES Bartlett RC (1959): Cephalothoracopagus. Arch Pathol68:292-298. Changaris DG, McGavran MH (1976): Craniofacial duplication (diprosopus) in a twin. Arch Path Lab Med El-Minawi MF, Shaaban H, Naguib Y, El-Sadek M, Shaaban A (1970): Human double monsters. Manage- Gunter JU (1946): Cephalothoracopagus monosymmetros. Report of a case. Am J Pathol 222355-861. 100:392-394. ment and radiologic features. Int J Gynaecol Obstet 8:618452. * Herring SW, Rowlatt UF (1981): Anatomy and embryology in cephalothoracopagus twins. Teratology Machin GA, Sperber GH, WootliK J (1985): Monozygotic twin aborted fetuses discondant for holoprosencepha- Moerman P. Fryns JP, Goddeeris P, Lauweryns JM, Van Assche