Figure 4

Syringes in Meckel Gruber and pyopagus twins. A Cross section of cervical spinal cord, Meckel Gruber with an occipital encephalocele. A small dorsal median cavity (arrow) is continuous ventrally with the dorsal glial raphe, but does not appear to connect to the mildly dilated and dorsally elongated central canal in this plane. B Same case, thoracolumbar cord: large dorsal syrinx with irregular lateral extensions (A and B: Immunohistochemistry for Vimentin). C Wall of syrinx in (B), with scattered histiocytes reacting positively for Iron (arrows, Perl’s iron stain). D Sacral spinal cords of pyopagus twins stained for alpha beta crystallin: one cord is a hemicord with a collapsed and dilated central canal (asterix). Both cords share a thin fibrolipomatous sheath within a single dural sac. More rostrally, the lumbar spinal cords of each twin separated and had distinct dural sacs within a common neural canal. E Cross section of thoracolumbar spinal of the cord oriented as the superior cord in D demonstrating a dorsally elongated central canal lined by ependyma and extending between the posterior columns. F The abnormality in (E) is duplicated in the thoracolumbar cord of the other twin.