Analyses of cellular mosaicism in chimeric mouse brains

The BTBR T+Itpr3^tf/J mouse is one of the most widely used idiopathic models of autism, reproducing core autism-like behaviors together with fixed neuroanatomical traits, most notably complete corpus callosum agenesis and hippocampal alterations. To test whether these traits are cell-autonomous or are imposed by the surrounding tissue environment, we generated inter-strain aggregation chimeras between BTBR and a GFP-expressing C57BL/6 line (B6-GFP), in which every cell is permanently traceable to its strain of origin by GFP (GFP⁺ = B6-derived; GFP⁻ = BTBR-derived). Brains were imaged by confocal microscopy and the strain composition of neurons (NeuroTrace/Nissl) and astrocytes (GFAP) was quantified across the cortex and hippocampus. The study finds that corpus callosum agenesis is rescued in the chimeric environment (a non-cell-autonomous trait), whereas hippocampal neurons and astrocytes segregate by layer in a strain-linked, cell-intrinsic manner. The dataset reports, for each brain area we examined, how many cells came from the B6 strain (green) out of all the cells counted. Each row is one measurement in one brain region of one mouse, and gives the number of B6 (green) cells, the total number of cells, and the percentage that were B6. It covers nine mice (CH1–CH7 plus two pups) and two brain areas — the cortex and the hippocampus (regions CA1, CA2, CA3, and the dentate gyrus) — and reports neurons and astrocytes separately, in both the main cell layer and the molecular layer, for both sides of the brain.