Quantifying microglial morphology: an insight into function

Abstract

Microglia are specialized immune cells unique to the central nervous system (CNS). Microglia have a highly plastic morphology that changes rapidly in response to injury or infection. Qualitative and quantitative measurements of ever-changing microglial morphology are considered a cornerstone of many microglia-centric research studies. The distinctive morphological variations seen in microglia are a useful marker of inflammation and severity of tissue damage. Although a wide array of damage-associated microglial morphologies has been documented, the exact functions of these distinct morphologies are not fully understood. In this review, we discuss how microglia morphology is not synonymous with microglia function, however, morphological outcomes can be used to make inferences about microglial function. For a comprehensive examination of the reactive status of a microglial cell, both histological and genetic approaches should be combined. However, the importance of quality immunohistochemistry-based analyses should not be overlooked as they can succinctly answer many research questions.

Keywords: glia; histology; immunohistochemistry; morphology.

Graphical Abstract

Figure 1.

Microglial morphologies. Microglial morphologies adapted from photomicrographs of Iba1-stained cells. (A) Ramified microglia. (B) Bushy or hypertrophic microglia. (C) Ameboid microglia. (D) Rod microglia. (E) Microglial scar. 3D projected images were processed in ZEN blue and edited in Illustrator. These images should be treated as representative diagrams.