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.

The connective tissue of the adductor canal--a morphological study in fetal and adult specimens.

The adductor canal is a conical or pyramid-shaped pathway that contains the femoral vessels, saphenous nerve and a varying amount of fibrous tissue. It is involved in adductor canal syndrome, a claudication syndrome involving young individuals. Our objective was to study modifications induced by aging on the connective tissue and to correlate them to the proposed pathophysiological mechanism. The bilateral adductor canals and femoral vessels of four adult and five fetal specimens were removed en bloc and analyzed. Sections 12 microm thick were obtained and the connective tissue studied with Sirius Red, Verhoeff, Weigert and Azo stains. Scanning electron microscopy (SEM) photomicrographs of the surfaces of each adductor canal were also analyzed. Findings were homogeneous inside each group. The connective tissue of the canal was continuous with the outer layer of the vessels in both groups. The pattern of concentric, thick collagen type I bundles in fetal specimens was replaced by a diffuse network of compact collagen bundles with several transversal fibers and an impressive content of collagen III fibers. Elastic fibers in adults were not concentrated in the thick bundles but dispersed in line with the transversal fiber system. A dynamic compression mechanism with or without an evident constricting fibrous band has been proposed previously for adductor canal syndrome, possibly involving the connective tissue inside the canal. The vessels may not slide freely during movement. These age-related modifications in normal individuals may represent necessary conditions for this syndrome to develop.

Effect of exogenous dehydroepiandrosterone upon the fetoplacental biosynthesis of estrogens and its effect upon uterine blood flow in the term pregnant ewe.

The fetoplacental unit of the ewe is capable of increasing the biosynthesis of estrogens following the exogenous administration of DHEA to the fetus. The maximum concentrations of estrogens appeared approximately 30 minutes after the administration of DHEA. Uterine blood flow in the pregnant ewe increased approximately 90 minutes after the maximum concentrations of estrogens were noted. The administration of DHEA to the nonpregnant, ovariectomized ewe did not elicit estrogen biosynthesis or changes in uterine blood flow. Isotope experiments in the pregnant ewe demonstrated the incorporation of DHEA into urinary estradiol.