IntroductionSince the mid 1950’s, very little work has been done to contribute to a better understanding of venous vasculature developpement during embryogenesis. We present a new analysis method with multiplanar reformation process based on microscopic sections. This présentation focus on the brain stem arachnoïdo-pial venous anastomoses evolutive morphology.Material and methodsHigh résolution numerised microscopic continuous sections (10 to 20 μ) from Carnegie stage XIX to XXIII human embryo were used. Specific image treatment was the following : binarisation-thresholding-labellisation, rigid shifting, median filtration (cubic matrix) (resolution 10μm/pixel) ; DICOM format images are exported for post-treatment process. Angiographic rendering was obtained thanks to the Eosine/hematoxylin red cell fixation within the vessels.ResultsAt first step, we confirmed the embryonnic status relatively to the Carnegie classification in assessing the cochlear canal orientation. The evolutive morphology of the brain stem primitive network is presented ; at stage XIX, the initial longitudinal veins are separated from the caudal plexus. During the next stages, we demonstrate how they connected to transverse pial anastomoses. The next period (i.e the early and late post-embryonic period) show these intrinsic pial veins lying between the arteries and the brain surface leading to a progressive simplication pattern. During the stages XX to XXIII, we present the changing morphology of the trijeminal ganglion venous plexus. These organisations are compared to the Padget and Streeter works.ConclusionWe present the preliminary work of the brain stem venous embryogenesis using 3D and angiographic rendering at the early post-embryonic stages.