Description: Segment 1 Gilliland introduces Thomas. Thomas speaks to camera and describes how the technique of electron microscopy has allowed for more detailed study of the peripheral nervous system. He shows a selection of slides, mostly taken from electron micrographs, of sections through nerves including the serial nerve and the perineurium. He explains in detail the differences between nodes and fibres, focusing one how they affect and alter the shape of each other. Time start: 00:00:00:00 Time end: 00:05:57:00 Length: 00:05:57:00 Segment 2 Thomas shows an electron micrograph of a myelinated nerve fibre - these are fibres surrounded by a myelin sheath which insulates fibres and axons from electrical stimulation. Next, myelinated nerve fibres are shown in electron micrograph studies, magnified to a very high level. Thomas then refers to a diagram to show the difference between myelinated and unmyelinated nerve fibres unmyelinated nerve fibres are often present where there is degenerative disease of the peripheral nervous system and in, for instance, multiple sclerosis. Time start: 00:05:57:00 Time end: 00:11:20:00 Length: 00:05:23:00 Segment 3 Thomas explains some of the causes for lesions in the nerve fibres. He refers in particular to Wallerian degeneration, a process which occurs when a nerve fibre's myelin surface has been cut or damaged. He shows diagrams and electron micrographs to illustrate this complex process. Time start: 00:11:20:00 Time end: 00:15:44:00 Length: 00:04:24:00 Segment 4 We see a series of diagrams and electron micrographs detailing different aspects of nerve cell degeneration. Thomas explains each form of degeneration at the most detailed cellular level. Time start: 00:15:44:00 Time end: 00:21:51:00 Length: 00:06:07:00 Segment 6 Thomas talks further about his experiment with colleague, Haftek. Through a series of electron micrographs he shows the damaged nerve at various stages after their initial compression of it with forceps from 1 hour after injury to 3 days later. After this, Thomas discusses nerve injury in which, rather than compression, there is complete transection the two endings of a nerve are completely severed from each other. He shows, using light microscopy, how new cells begin to grow from each stump of the severed nerve - some of these can grow quite long and are often called 'ghost nerves.' This process of new growth from severed nerve endings is known as nerve regeneration. Time start: 00:24:59:00 Time end: 00:30:55:00 Length: 00:05:56:00. Segment 7 Thomas talks further about nerve regeneration, using as an example, an experiment on the peroneal nerve of a rabbit. He plots the regrowth of nodes against those of fibres on a graph the fibres grown back to almost normal length while the internodal length remains very stunted. Thomas next discusses an experiment by Paul Weiss which aimed to show how regeneration occurs in a crushed nerve fibre the stages of this experiment are shown in electron micrographs. Time start: 00:30:55:00 Time end: 00:35:47:00 Length: 00:04:52:00. Segment 8 Thomas concludes with a discussion about the regeneration of unmyelinated nerve fibres. He refers to diagrams and electron micrographs of an experiment on a rabbit with a crushed vagus nerve. This study shows that unmyelinated nerve fibres can also regenerate in a pattern almost identical to that of myelinated fibres. However, this seems to be dependent on the presence of myelinated fibres close by at the time of regeneration. Thomas admits that this process is not yet fully understood. Time start: 00:35:47:00 Time end: 00:40:35:18 Length: 00:04:48:18