Quantitative Assessment of Hippocampus Architecture Using the Optical Disector

The optical disector, one of the most commonly used design-based stereological techniques, enables accurate counting of total number of objects (neurons, synapses) using thick 2D sections through the reference space of interest. The optical disector applied to thick immunostained sections requires attention to several technical issues. Differential shrinkage of tissue presents a major problem for accurate density estimation by the optical disector. The hippocampus, a major limbic structure, and its contribution to learning and memory have consistently attracted the interest of neuroscientists. the hippocampus is composed of complicated 3D networks of neural connections. The authors review the spatial distributions and provide density estimates from optical disector counts of eight classes of GABAergic neurons in the hippocampus defined by the following neurochemical markers: three calcium-binding proteins; four neuropeptides; and neuronal nitric oxide synthase (NOS).