The morphological study of the human brain stem up to date has been centered chiefly on the description of fiber tracts and nuclei. As their location and extent has become sufficiently clear, further research is required on these structures to evaluate them quantitatively. Not until complete inform a t' ion of that nature is collected, can we hope to obtain a perfect concept of the functioning of the Central Nervous System.
I n the study presentecj here, we undertook to examine at least one cell group quantitatively. At our disposal was a complete series of transverse sections of the brain stem of a 42 year old male. The subject from whom we procured this specimen was reported free of neurological disorders. The brain stem was fixed in formalin, embedded in paraffin and sectioned at 2011. Using toluidine blue, the sections were stained by Nissl's method.
Because it forms a well defined cell group, we selected for our study the motor trigeminal nucleus. The nuclei of the cranial nerves, other than those for the eye muscles, have, to our knowledge, not been considered from a quantitative point of view. Our idea of a quantitative study is to assess as many measureable features of a structure and of its component elements, as possible. Such information, however, is only a first step towards providing normal standard values for future consideration of individual variations and differences.