Three-dimensional reconstruction of the lower limb's venous system in human fetuses using the computer-assisted anatomical dissection (CAAD) technique.

Objective: The aim of the present study was to show the feasibility and describe the first results of a 3D reconstruction of the venous network of the lower limbs in human fetus using the computer-assisted anatomical dissection (CAAD) technique.
Materials and Methods: We used limbs from two human fetuses, respectively, 14 and 15 weeks gestation old. Specimens were fixed in 10% formalin, embedded in paraffin wax and serially sectioned at 10 m. The histological slices were stained using HES and Masson Trichrome for soft tissues identification. Immunolabeling techniques using the Protein S-100 marker and the D2-40 marker were used to identify nerves and vessels, respectively. Stained slices were aligned manually, labeled and digitalized. The segmentation of all anatomical structures was achieved using the WinSurf(®) software after manual drawing.
Results: A 3D interactive vectorial model of the whole leg, including skin, bone, muscles, arteries, veins, and nerves was obtained. In all limbs, we observed the presence of a big axial vein traveling along the sciatic nerve. In addition, the femoral vein appeared as a small plexus. Although this is a common anatomical feature at the end of organogenesis, this feature is observed in only 9% of adults. Usually interpreted as an "anatomical variation of the femoral vein" it should be considered as a light truncular malformation. These observations bring further support to our proposed "angio-guiding nerves" hypothesis.
Conclusion: This preliminary study shows that the CAAD technique provided an accurate 3D reconstruction of the fetal leg veins anatomy. It should bring a new insight for the understanding of the different steps of development of the human venous system.