Figure 3

Characterizing performance of surface-profile-guided CNC machining of the skull: (a) Photomicrograph of the 50 μm deep test milling path on the right hemisphere ~4 mm posterior to bregma and ~1.5 mm lateral to midline, drilled using the 300 μm ball end mill. Grid size, 500 µm; scale bar, 250 µm (b) Cross-sectional profile of the trenches drilled with the (i) 300 μm ball end mill and (ii) the 200 μm square end mill constructed from the photomicrographs. (c) Boxplot of the measured trench depth for each of the four possible combinations of surface profiling and cutting tools. The dashed line represents the target depth of cut, in contrast with the median value for each combination shown in red. (d) Histograms of trench depths for milling with the square end mill and the ball end mill after surface profiling with the ruby sphere stylus. (e) Average microglia cell counts in tissue near the cortical surface of area 891 × 662 µm as imaged at 10X magnification in mice that underwent automated surface milling and non-surgical control mice. (f) Representative images of stained microglia via Iba1 staining and DAPI shown in both mice that underwent automated surface milling and non-surgical control mice. Images were taken at 10X magnification (top row) and 20X magnification (bottom row). Scale bars, 100 µm.