Diagram and photograph of the BM microvasculature. (A) Scheme illustrating the BM vasculature with an arterial supply ramifying into a capillary network and drained by a venous sinusoidal network. (Source: http://www.accesmedicine.com.) (B) Vascular casts showing the BM microvasculature with slender arterioles supplying an anastomosing venous network. (Source: http://visualsunlimited.photoshelter.com.)