USC Banco de Imagenes Médicas

Neural Tissue

Micro 101. Diagram of the developing CNS and PNS (Jones, The Structural Basis of Neurobiology, 1983). The two major subdivisions of the nervous system, the central nervous system (CNS - consisting of the brain and spinal cord) and the peripheral nervous system (PNS - consisting of the various ganglia and peripheral nerves) are integrated into a functional network. In the lower phyla of the animal kingdom this distinction between CNS and PNS is less obvious.

Micro 102. LM of spinal cord. In the one corner of the Micro is an example of a neuron with a characteristically prominent nucleus and nucleolus and strongly basophilic cytoplasm.

Micro 103. Diagram of surface area to shape relationship (Fawcett, The Cell, 1981). Increasing surface area by simply increasing cell size increases the amount of cellular volume that must be metabolically maintained. As noted in the diagram, the amount of surface area of a cell (assuming a constant volume) is also related to the shape of the cell.

Micro 104. Diagram of a neuron (Lenz, Cell Fine Structure, 1971). Most of the neurons of the mammalian brain are multipolar cells displaying a single axon (lower right) and numerous dendrites. Dendrites and the cell body contain Nissl substance while the axon lacks ribosomes.

Micro 105. Diagram of synaptic ending (Fawcett, Bloom and Fawcett: A Textbook of Histology, 1986). Release of neurotransmitters at chemical synapses is a highly specialized form of regulated cellular secretion. Like other cells involved with active secretion, the fusion of secretory vesicles (i.e., synaptic vesicles in nerve terminals) with the cell membrane is accompanied by the retrieval of the excess membrane.

Micro 106. LM of osmium fixed peripheral nerve in cross section and longitudinal section (Webster, The Peripheral Nervous System, 1974).In the cross section at the top, the myelinated axons appear as light centers (the axon) with darkly stained rings (the myelin). In the longitudinal section below you can see a gap between two adjacent myelin segments (top arrow). This unstained gap region is the node of Ranvier, the site of sodium flux in saltatory conduction.

Micro 107. Semidiagramatic representation of the meninges in the skull (Haines, Anat. Rec. [1991] 230:3). The large dots indicate the location of collagen fibers and not the size or orientation of collagen bundles.

Micro 108. NO HAY. LM of a dorsal root ganglion. In the center of the field is a dorsal root ganglionic neuron with a prominent nucleus and nucleolus. Also note the basophilic staining of the Nissl substance.