biology blood capillary cells education haemoglobin human laboratory life microscope microscopy oxygen red red blood cells science slide smear tiny abstract background blood cells body carbon dioxide cell count circulation concept corpuscle design disease erythrocyte fill graphic health hemoglobin illness iron macrocyte medicine megaloblast megalocyte microscopic New original platelets render sickness style texture transfusion unique vector breakable brown brown-eggs calcification calcium-carbonate chicken-eggs colored coloring colors coloured colouring colours cook cooking egg eggs eggshells external farm-fresh food fragile fragility fresh fresh-eggs hens-eggs mottled mottling outer-covering outside oval oviduct ovoid pigmentation pigmented-shells pigmenting protoporphyrin speckled surface surfaces surfacing textured textures variety various