Scanning electron microscopy (SEM) study on filum terminale with human fetus

The filum terminale plays an important role in the pathophysiology of tethered cord syndrome (TCS). The study on ultrastructure of fetal filum can provide reference standard for diagnosis of TCS. Eleven fresh Chinese human aborted fetuses had their fila measured and removed. Transverse and longitudinal sections of the middle and distal segments of fila were submitted for scanning electron microscopy (SEM) analysis respectively. The bulk of the filum terminale is composed of 1 μm to 5 μm thick spring like longitudinal bundles of collagen separated by 5 μm to 30 μm layer intervals and 1 μm to 5 μm intervals in the layer, although a small quantity of capillaries and other components may be present. A delicate meshwork of collagen transverse fibers connects these bundles and fibers in every bundle. A delicate meshwork of collagen transverse fibers connects these bundles and fibers in every bundle. A complex tridimensional structure is evidenced on electron microscopy. In conclusion, a complex tridimensional structure composed by ordered arrangement of spring-like fibers and a small quantity of capillaries should elicit considerable elastic properties to the filum terminale. Its alternation of structure and component may be involved in TCS closely.