(conjoined twins) Monozygotic twins with variable incomplete separation into two during cleavage or early stages of embryogenesis. (Makris S, Solomon HM, Clark R, Shiota K, Barbellion S, Buschmann J, Ema M, Fujiwara M, Grote K, Hazelden KP, Hew KW, Horimoto M, Ooshima Y, Parkinson M, Wise LD. Terminology of developmental abnormalities in common laboratory mammals (Version 2). Part B. Birth Defects Res B Dev Reprod Toxicol. 2009 Aug;86(4):227-327.)

(conjoined twins) A monoamniotic twin gestation in which the twins share one or more organs.

MONOZYGOTIC TWINS who are joined in utero. They may be well developed and share only a superficial connection, often in the frontal, transverse or sagittal body plane, or they may share a partial duplication of a body structure. Alternatively, there may be a small and incompletely developed twin conjoined to a larger, more fully developed twin.

Conjoined twinning is one of the most fascinating human malformations and has also been reported in other animals�mammals, fishes, birds, reptiles, and amphibians. Treating conjoined twins can be a daunting challenge for the surgeon.

Conjoined twins are two babies who are born physically connected to each other.

Conjoined twin, one of a pair of twins who are physically joined and often share some organs. Fusion is typically along the trunk of the body or at the front, side, or back of the head. In the case of symmetrical conjoined twins, the children usually have no birth anomalies except at the areas of...