Fig. 4. Complete depletion of GABAergic neurons in the SC of postnatal mice. (A-D) Gad65 expression in the postnatal superior colliculus (SC) of wild-type (A,C) and homozygous mutant mice (B,D). There is complete depletion of Gad65-expressing cells in the SC, whereas the ventral midbrain (vMb) and cortex are unaffected. Gad65-expressing cells in the inferior colliculus of homozygous mouse (D) are reduced compared with in the wild-type mouse (C). (E-H) Calbindin immunohistochemical staining of the SC of wild-type and homozygous mutant mice. The layers and patches characteristic of the cytoarchitecture of the superior colliculus are unaffected (E,F). (G,H) Higher magnification of the SC cytoarchitecture showing no obvious difference in the wild-type (G) and the Mgn^tZ/tZ (H) mice. Abbreviations: Zo, zonal layer of the SC; SuG, superficial grey layer of the SC; Op, optic layer of the SC; InG, intermediate grey layer of the SC; InWh, intermediate white layer of the SC.