Spatial relationship of histochemically demonstrable patches in the mouse superior colliculus

Patches of high phosphorylase activity are found in the intermediate and dorsal deep grey layers of the mouse superior colliculus when either coronal or sagittal sections are cut. These patches indicate that the phosphorylase a activity is arranged in a continuous lattice composed of bands of high phosphorylase a activity with a width of 100-200 microns that surround pale islands of low activity. This lattice was demonstrated by cutting surface parallel sections through the partially flattened superior colliculus. An almost identical lattice is observed in sections incubated to demonstrate total phosphorylase or cytochrome oxidase (CYO) activity. This phosphorylase/CYO lattice extends over the entire area of the superior colliculus. A discontinuous staining pattern is also observed in the intermediate and deep grey layers of both sagittal and coronal sections incubated for acetylcholinesterase (AChE) activity. The staining is arranged in two discontinuous sheets of intense activity that are joined together by vertical streamers. In surface parallel sections the AChE activity is found to form a network pattern which extends over the entire extent of the superior colliculus but which becomes fainter at the anterior pole. The phosphorylase/CYO lattice is not in register with the AChE lattice and the two seem to be organized independently of each other despite occurring at the same depth.