Fig. 1: In vitro Gitterzellen formation.

a Gitterzellen shown in Alzheimer’s camera lucida drawings in post mortem tissue (from Kettenmann et al. ²⁷; with permission of the American Physiological Society). b,c Gitterzellen seen by live cell imaging in mouse primary microglial cells exposed to Lef-NP [1:1000] (b) or ceramide-coated nanoparticles (Cer-NP) (c). d–k Characteristic vacuolated phenotypes seen in Lef-NP-treated microglial cells (phase contrast, live cell imaging) (d-g) and scanning electron microscopy (h–k): foam phenotype (d, h), early (multivacuolar) and advanced (oligovacuolar) Gitterzellen (e,f and i,j) and ballooning (monovacuolar) Gitterzellen (g,k). Frequently, the progression of Gitterzellen towards advanced stages is marked by the formation of one or two enlarged vacuoles surrounded by numerous smaller ones, a phenotype that is also documented by Alzheimer’s camera lucida drawings (blue arrows in Fig. a–c). Notably, the cell nucleus is condensing during Gitterzellen progression, but remains detectable until terminal stages (red arrows in d–g). Scale bars are: 20 µm (b,c), 10 µm (d–k).