<Tr> <Td_colspan="2"> Transmission electron microscope image of a cross-section of a capillary occupied by a red blood cell . </Td> </Tr> <Tr> <Td_colspan="2"> A simplified illustration of a capillary network (lacking precapillary sphincters, which are not present in all capillaries). </Td> </Tr> <Tr> <Th_colspan="2"> Details </Th> </Tr> <Tr> <Th_colspan="2"> Identifiers </Th> </Tr>

Which of the following do veins have that are lacking in arteries