ZOOL 409 TUESDAY Objectives: Examine slides featuring nerve cells and peripheral nerves. 1. Slide 88 -- Spinal cord smear. This is a smear preparation, not a section (i.e., a bit of spinal gray matter, not sliced but simply spread out and pressed down on the slide). This may be our best slide to see some of the shape of nerve cells. Lab Week 13 Tuesday and Thursday Note texture of cytoplasm with Nissl bodies (basophilic granules representing rough endoplasmic reticulum ). Note dendrites tapering away from cell bodies. o In slide boxes 1 and 8, look on each neuron for a pale axon hillock and thin pale axon. This feature will not be visible on most nerve cells (depending on how the cells was flattened onto the slide) and may not be apparent anywhere on a given slide. 4. Slide 10 -- Peripheral nerves. This slide of "artery, vein, nerve" includes relatively large nerves cut in cross section. The conspicuous space between nerve sheath and nerve fibers is an artifact from tissue shrinkage. The sheath is fibrous connective tissue (mostly collagen and fibroblasts). Nuclei that appear among the nerve fibers belong to Schwann cells. 5. Slides 32, 62, 76 (and more) -- more nerves. Peripheral nerves may be found on many different slides. Look in connective tissue (often near larger blood vessels) for a bundle of fibers enclosed in a more-or-less distinct sheath. 6. Slide 86 -- Nerve spread. Note very numerous small nuclei belonging to glial cells. This slide displays a bit of nerve teased apart and flattened on the slide, not sliced. Some blood vessels may also be stretched across the specimen. Myelin and nodes of Ranvier should be visible. Most of the thickness of each nerve fiber is myelin; nodes are the neat gaps that appear between one myelin segment and the next. 2. Slides 89, 90, 91, 92 -- Spinal cord sections, with various stains. Nerve cell bodies appear prominently in the ventral horn (the shorter, broader arm of the "H" of gray matter). Slide 92 includes nerve roots and dorsal root ganglion. 3. Slides 91, 92, and more-- Ganglia. On slide 91 and 92, look for dorsal root ganglion beside the spinal cord. Slide 91 is a Golgi stain for Golgi bodies. Also see Auerbach's plexus, in the GI tract (e.g., slides 42, 43, 45, 44), between the circular and longitudinal layers of smooth muscle. 7. Slide 87 -- Motor nerve endings. This slide is a bit of striated muscle (not a slice, but a spread) dissected at the site where a motor axons synapse with muscle fibers. Hunt for the long black nerve fibers, then try to follow them to motor end plates. Practical Quiz: see reverse side. THURSDAY Objectives Central Nervous Tissue. See reverse side of this page. An autonomic ganglion can be found on slide 32 in Boxes 1,4,7,8 and on slide 71 in Boxes 2,3,4,7. Last updated: 8 April 2013 / dgk ZOOL 409 Tuesday and Thursday Lab Week 13 TUESDAY Objectives: See reverse side. ARTEFACT ALERT THURSDAY Objectives: Nervous tissue is difficult to fix well, and often displays substantial shrinkage. This is manifested as "halos", or clear empty spaces surrounding various structures, particularly blood vessels and nerve cell bodies. Examine some regions of the Central Nervous Tissue. 1. Slides 89, 90, 91, 92 -- Spinal cord sections, with various stains. Distinguish gray matter, forming an "H" or "butterfly" shape surrounded by white matter. Note cell bodies of motor neurons in the ventral horn, the shorter, broader arm of the "H" of gray matter: Distinguish white matter, forming dorsal, ventral, and lateral columns of axons travelling up and down the cord. 2. Slides 96, 97, 98, 99, 100 Cerebral cortex. On all of these slides, find nerve cell bodies and note the associated volume of neuropil (consisting of dendrites and axons, where most synapses are located). Note many blood vessels. Slide 98 is a Golgi stain for nerve cells and astrocytes. Astrocytes are also demonstrated on Slide 99. Slides 96 and 97 are silver stained, offering some sense of neuropil structure. Slide 100 is stained for microglia, probably frog brain. (In blood vessels, red blood cells have nuclei.) 3. Slides 94, 95 -- Cerebellar cortex. On these slides, note the distinct layers, with large cell bodies of Purkinje nerve cells in the Purkinje cell layer between the granule cell layer and the molecular layer. Although such halos are artefacts, they are also a fairly standard "feature" that helps call attention to blood vessels and nerve cell bodies. The viewer must bear in mind that surrounding neuropil should be closely apposed to the haloed structures. Practical Quiz This quiz will simply confirm recognition of some basic features on your slide-box slides. □ □ □ □ □ □ □ □ On slide 88: Indicate the nucleus of a neuron. Indicate the nucleus of a glial cell. On slide 91 or 92: Indicate nerve cell body in ganglion. On any appropriate slide: Indicate nerve cell body in an autonomic ganglion.. On slide 90 or 92: Indicate white matter. Indicate nerve cell body in ventral horn. On slide 86: Indicate a node of Ranvier. On slide 62, 32, 34, 76, etc.: Indicate a peripheral nerve. On slide 93, 96, 97, 98, 99, 100: Distinguish nerve cells from glia. Indicate a blood vessel. On slide 94 or 95: Indicate a Purkinje cell. Last updated: 4 April 2013 / dgk