Study on the morphology and ultrastructure of fetus filum terminale

Abstract

Objective The filum terminale(FT) plays an important role in the pathophysiology of tethered cord syndrome (TCS). The study on morphology and ultrastructure of fetus FT can provide reference standard for diagnosis of TCS . Method Eleven fresh human aborted fila fetuses had been measured and removed. Transversal and longitudinal sections of the middle, and distal thirds of FT were submitted to light microscopy analysis with four different techniques. Four ilia were selected for longitudinal and transversal scanning electron microscopy analysis. Results The bulk of the FT was 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 elements may be present. A delicate (0.13 μm) meshwork of collagen transversal fibers connects these bundles and fibers in every bundle. Collagen bundles could also be found between layers and bundles. Abundant longitudinally oriented elastic fibers were found inside or between collagen bundles. A complex tridimensional structure was evidenced on electron microscopy. Conclusions A complex tridimensional structure composed by ordered arrangement of spring like fibers and small quantity of capillaries should elicit considerable elastic properties to the FT. It's alternation of structure and element maybe involved closely in TCS. Key words: Filum terminale, fetus; Tethered cord syndrome; Anatomy