Blood Vessel Structure and Function:

Current histology texts devote very little space to the description of vascular structure. In general, the main vessels (with the exception of the capillaries) are composed of 3 'tunics'. The tunica adventitia is the outer coating of cells, comprising mainly macrophage and fibrocyte cells. The adventitia also provides support for the postganglionic sympathetic nerves that innervate some vessels and which terminate at the adventitia medial border in arteries and slightly deeper in the veins. The inner layer of endothelial cells (EC's), which form the endothelium, are generally flat cells which are in contact with the blood and are referred to as the tunica intima. Between the intima and adventitia is the tunica media. The media is composed of smooth muscle cells (SMC's), elastin and collagen fibres.

Confocal microscopy together with fluorescent nuclear stains enables the identification (in 3 dimensions) of cell number, type, orientation and (in some cases) viablity.
The image above shows an 'extended focus' view of a human resistance artery stained with the nuclear stain H33342. All of the acquired optical slices are shown together to show the position of the adventitial, smooth muscle and endothelial cells.
The panel above shows an extended focus view (left) and a simulated flurescence projection (right) calculated from the same data sets. This is an example of two ways in which serial confocal optical sections can be displayed.
A small cerebral artery is shown above as a simulated fluorescence projection.

Another approach (shown above) is to render a 3D volume. This has the advantage that measurements can be made on the 3D volume.