Motility and migration of activated microglia in a neonatal rat hippocampal tissue slice culture

Time-lapse sequence in tissue slice culture (from postnatal day 6 rat, 2 days in culture) stained with IB4 lectin (green) and ToPro3 (red = nuclei of dead cells).  The image represents a composite of nine optical images spanning 40um in depth.  Note the microglial movements, mitotic cell divisions, and phagocytosis of dead cell nuclei. (See Petersen & Dailey, 2004).

Higher magnification view showing dynamics of microglial motility

Note a mitotic microglial cell (lower left of center) near the beginning of the time sequence.  Also, near the end of the time sequence, a microglial cell sweeps in from the upper left corner and picks up a dead cell nucleus "on the fly".  Movie by Mark Petersen. (See Petersen & Dailey, 2004, Fig. 4).

Microglial response to laser burn in brain slice P2X7-KO

Microglia cell bodies and branches (green) are visible due to expression of green fluorescent protein (GFP) in this mouse line (P2X7-/-:CX3CR1GFP/+).  The many healthy cells in the tissue are unlabeled.  Time-lapse movie under baseline conditions (00:00-00:17) show continual remodeling of microglial branches.  Focal tissue injury (00:17) was induced along a line by brief exposure to high intensity laser light (white line between white arrowheads).  Within minutes, injured cells begin to take up a membrane-impermeable red fluorescent DNA-binding dye, ToPro3, and nearby microglia extend branches (yellow arrowheads) toward the laser-damaged cells (00:28).  Within a couple of hours, stationary microglia have transformed to activated fusiform or amoeboid microglia that migrate and accumulate near the injured cells (01:47). These data demonstrate that microglia extend branches and migrate toward injured cells (previously shown to be dependent on extracellular ATP) in the absence of P2X7-type purinoceptor.  Time is shown in hr:min. From Eyo & Dailey, J. Neuroimmune Pharmacol, 2013.

Microglial motility facilitates rapid mobilization to and phagocytosis of injured neurons

In this case, injury was experimentally induced in a mouse hippocampal tissue slice by focal laser burn.  Within minutes after the injury, an activated amoeboid microglial cell (expressing GFP) extends a branch toward a Sytox-labeled nucleus of an injured neuron, contacts it, and engulfs it.  Time is shown in hr:min.   From Eyo & Dailey, J. Neuroimmune Pharmacol, 2013.


Astrocytes in rat hippocampal slice cultures develop a complex 3-D morphology

This movie shows a three-dimensional reconstruction of a rat astrocyte expressing LCK-GFP, a membrane-targeted GFP.  A confocal microscope was used to image the cell in a cultured hippocampal slice.  From Benediktsson et al., Journal of Neuroscience Methods 141 (2005) 41–53.