Histological and histoenzymological studies on the medulla oblongata and pons of hedgehog (Paraechinus micropus).

A comparative study of the acid and alkaline phosphatases within the medulla oblongata and pons of the hedgehog revealed the following facts: 1. All the cellular elements are positive for acid phosphatase, irrespective of their sensory or motor nature, and the large neurons of all the nuclei are more strongly positive than the small cells. Furthermore, the nuclei which contain a dense population of neurons, appear to be more strongly positive than areas containing scattered neurons. 2. Alkaline phosphatase preparations show a strong activity in the walls of blood capillaries of all the nuclei of the medulla oblongata and pons. Reaction of this enzyme in the neuropil varies from strong (NNH, NPH, VSP, VM, VS, VL, OLS, NI, NRM), over moderate (reticular nuclei, NS, TSN), mild (NA, NRL) to absent (AP). A few nuclei such as OLS, NT, VM, VL, VS, NPH, and NI also show activity in neurons, which appears to be localized at the periphery of the cells only. The significance of the distribution of these enzymes at the various locales are discussed from a functional point of view.