SOMATOTOPIC PROJECTIONS OF THE CUTANEOUS FACIAL REGIONS TO THE SUBSTANTIA GELATINOSA OF THE RAT AN ACID PHOSPHATASE STUDY / 解剖学报

ABSTRACT

The substantia gelatinosa of subnucleus caudalis of the trigeminal nerve of the rat shows an intense extralysosomal acid phosphatase activity which disappears after the removal of it's skin of the facial regions.Different regions of the facial skin of 69 rats were excised and the projections of the cutaneous nerves were traced by studying the extralysosomal acid phosphatase activity with the modified Gomori's methods.A somatotopical localization was found within the substantia gelationosa. It agreed with what has been found in earlier studies where other techniques have been used. The findings showed that the fibers of the cutaneous areas along the dorsoventral axis of the body were found in a reverse order in the receptive fields in the substantia gelatinosa. The vertex and fore-head lay in the ventral, while skin of the mandibular areas in the dorsal region, and the skin of the facial areas lay successively from ventral to dorsal in following order vertex and forehead eye region, dorsal vibrissae, ventral vibrissae-upper lip and finally lower lip-mandibulare region, in the receptive fields of the substantia gelatinosa.The cutaneous facial regions were disproportionately represented in substantia gelatinosa, for example, the field receiving projections from the vibrissae areas or fields were as large as 4mm~2 in the most medial portion of the ventral vibrissae-upperlip which are disproportionately large while the fields receiving projections from the forehead and mandibular cutaneous regions were disproportionately small. The provides a possible explanation for the specific function of analgesia of the acupuncture point Renzhong.