Stereology Symbols

Like many disciplines, stereology has it’s own set of terms and symbols The basic symbols are uppercase letters that represent different types of quantities.

A Stereology differentiates between the area in a plane and surface area which is area in 3-d. A thin section of of tissue has profiles on it that have area. A photograph or other image is flat and shows area. A lake in a photograph has area.
B The outlines of objects on a plane have length, boundary length. Stereology differentiates between the length of objects in 3-d and the lengths of boundaries just as area and surface are seen as two distinct quantities.
N The number of particles. The number of cells in the kidneys and the number of synapses in the brain are examples of numbers of objects.
L Length is a 3-d quantity. This might be the length of dendrites or capillaries. Length is seen as being distinct from boundary.
S Surface area is a 3-d quantity. Stereologists are clear to distinguish surface area from the area seen in something flat such as a thin section of rock or an image. A cell is bounded by a surface.
V Volume is a 3-d quantity. The size of a ventricle is an example of volume.
v Volume of an individual member of the population. The volume of a cell, rather than the volume of all of the cells is a good example of the use of a lower case v.

These basic symbols are often used in a subscript form. The subscript can be read as per unit. An example makes this easy to understand. Suppose the estimate is capillary length per unit volume. The quantity is written as L v . The symbol L stands for 3-d length and the subscript V is per unit volume. Another common symbol is N v. This stands for number per unit volume. This might be the number of cells per unit volume. The notation V v is volume per unit volume. An example of this is how much plaques there is in the hippocampus. A value of .2 means that the hippocampus is 20 percent plaque by volume.

There are a number of symbols that are used less frequently. These symbols are more common in some disciplines within stereology than in others.

I Intersections are the number of places that a probe and an object come into contact.
J The symbol J is occasionally used in place of L.
C Total curvature of a curve in the plane. This is the net angle through which the unit tangent vector rotates as a point traverses the curve.
K Integral of mean curvature
Q The number of objects is often written as a Q. This does not stand for quantity. It is likely that is derived from the Swiss word for profile. That word begins with the letter ‘Q’.

Other symbols that might be seen in stereological work are:

* The asterisk is often used to denote the star volume. This symbol appears as a superscript.
^ An upwards pointing arrow is often used to denote the intersections between a probe and the region of interest.