EMBRYO‐FORM PROJECT: HOW ACCURATE WAS MISS D. PADGET? STUDY OF THE HUMAN VENOUS CEREBRAL SYSTEM

Throughout her entire work, Miss Padget gave to the international scientific community several rules concerning the setting of the superficial venous network of the brainstem. These rules can be extended to the whole brain venous organization. She described the venous vascular organization in seven phases. We proposed to review and illustrate the overall venous human embryonic organization using the latest current 3D‐reconstruction possibilities “The Embryo‐form project” MATERIAL & METHOD We recently published the method (1) of this systematic reformation process and the material used selected among the French university collections in the framework of a conservation program (under the auspices of the French Morphologists Association). Permission and consent were obtained by the local ethic committee (CRENHU; University Hospital Nancy, France). This gathering brought together 20 human embryos prepared in serial histological sections, collected during the mid 50's. We also get access to the Carnegie's embryos collection thanks to her curator Miss E Lockett. 20 Embryos were digitalized with a flatbed scanner at 2400 DPI resolution. RESULTS Thanks to this method we were able to reconstruct 20 embryos, which present good vascular enhancement (due to histologic dye or direct vascular injection of India‐Ink). We have compared our results to the classic artwork of Miss Padget, confirming the global pattern of the 3 first stages consisting in the organization of primitive dural sinuses composed of three main stem: the anterior, middle and posterior dural plexus draining the neural tube. At stage 4, the neural tube is covered by a plexiform capillary net draining into short veins at the dorsal and ventro‐lateral aspects of the neural tube, and joining the dural venous plexus formed in former stages: the primary transverse anastomoses. During the next phases (Padget phase 5 and 6), at CS 19‐20‐21, and due to the growth of the cerebral vesicles, these short pia‐arachnoïdal veins i.e. the primary transverse anastomoses, were stretched. This phenomenon led to a reduction in number, leaving only one to two veins on each side of the neural tube: the vascular cleavage phase. We observed in the next stage (stage 6 ‐ CS 20‐21) the further establishment of pia‐arachnoidal veins anastomoses, particularly visible at the metencephalic level, by extension of the longitudinal anastomoses. Our pictorial essay is meant to present new views of the developing venous network of the brain stem and to illustrate some additional hemodynamic solutions depicted in different embryos. Conclusion Our technique opens new perspectives for re‐use and analysis of “historical” microanatomy collections. We provide an accessible, costless, and reliable method for three‐dimensional analysis of recent or old histologic collections. Our technique provides a powerful tool for understanding the making of the human cerebral vasculogenesis based on the legacy of Miss Padget and its remarkable and detailed anatomical drawings.