5. Neurons/Synapses/Glia


penicillin is toxic to CNS neurons (blood-brain barrier prevents: but infection allows meninges to absorb some penicillin)

tetracyclines readily cross blood brain barrier



1. Cresyl violet: Nissl bodies = Rough ER; stains DNA and RNA

2. Golgi: dendritic trees

3. Weigert: stains lipid (myelinated axons) black

4. Pyradine: stains neurofilaments (myelinated and unmyelinated axons) black


Cell types

1. Neuron

                        - dendritic spines

                                                - thin = slower (young, retarded, etc.)

                        - axons have mitochondria (no ribosomes)

                        - Golgi Type I: long axons

                        - Golgi Type II: short axons (interneurons)

                        - Synapses

                                                - Gray’s Type I: asymmetric (excitatory):

                                                - Gray’s Type II: symmetric (inhibitory): glycine, GABA, ACh

2. Glia

                        a. Neuroglia = macroglia

                                                i. Astrocytes

                                                - scars in the CNS (found in MS patients)

                                                ii. Oligodendrocytes

                                                - myelination

                        b. Microglia

                        c. Macrophages

3. Other

                        a. endothelial cells