Fig. 3

Electron micrographs. Few normal neurons in the cerebral cortex in a control rat (a). They show a round or oval nucleus with fine and discrete chromatin clumps. Profiles of myelinated axons are seen in the neuropil. At a higher magnification (b), axon terminals (AT) makes synaptic contact with dendrites (d) are common. Note the presence of a granular synaptic vesicles (asterisk) in the terminal; synaptic membrane thickening is evident. In rats given LPS injection at 28 days (c), some neurons show enhanced electron density in both the soma and dendrites (DN). An activated microglia (Mi) is seen closely associated with the soma of a “darkened neuron” (c, d). In an enlarged view (d), the “darkened neuron” showed dilated profiles of rough endoplasmic reticulum and mitochondria with disrupted cristae. The nucleoplasm of the “darkened neuron” also shows increased density (e). Profiles of “darkened dendrites” (dd) often appear to course through the neuropil (f). In the neuropil are present myelinated axons with disrupted myelin and contain dense inclusions (g). Axo-dendritic synapses in which some synaptic vesicles (circled) are swollen, clumped, and aggregated near the presynaptic membrane (h, i). AT, axon terminal; d, dendrite, DN, darkened neuron; Mi, microglia. Scale bars are indicated in the respective images