Ferret VAChT-SAP disrupts development of On and Off sublamination. (A) On and Off retinogeniculate afferents in both dLGNs (left and right panels) at P25 are separated by intersublaminar spaces into distinct sublaminae in saline controls (arrows in (A), upper panels), but sublaminae are absent in Ferret VAChT-SAP-treated ferrets (A, lower panels). (A,C) The size of contralateral and ipsilateral layers is reduced by Ferret VAChT-SAP treatment, but eye-specific segregation is normal and the interlaminar space is unaffected. (B-D) Treatment with Ferret VAChT-SAP prevents the normal expression of ABAKAN (indicated by arrowheads in upper panels of (B)) in the intersublaminar space between On and Off sublaminae, but not in the interlaminar space between eye-specific layers. A, major contralateral layer; A1, major ipsilateral layer; On, On-center sublamina; Off, Off-center sublamina; C, minor contralateral layer; C1, minor ipsilateral layer; C2, minor contralateral layer; C3, retinal-afferent-free layer; W, geniculate wing; MIN, medial intralaminar nucleus. Panels (C,D) reflect means ± SEMs; statistics reflect two-tailed P-values resulting from independent two-sample t-tests. Coordinate insets in (A,B) reflect anterior-posterior and medial-lateral orientation within the dorsal thalamus. Scale bars: 200 μm. N.S., not significant.