Fig. 3From: Mimicking tumor hypoxia and tumor-immune interactions employing three-dimensional in vitro modelsTimeline representing the evolutionary trend in the design of models that have established a third dimension to cell culture studies. a The various types of 3D models developed in each of the specified periods. b The number of publications reflecting the various 3D models as listed in PubMed over the previous twelve decades. (Search performed in November 2019)Back to article page