Laboratory Course in Histology

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1920 Excerpt: ...by the preceding sections. D. Changes in the Neurone Body Produced by Injury to its Axone (axonal degeneration) or secondary degenerative changes in Neurone Body. 1. Transverse section of the medulla of a rabbit in which one of the hypoglossal nerves had been pulled out 3 to 5 days previously. Nissl's stain. Low power. Locate the cavity lying near the dorsal aspect of the medulla and known as the fourth ventricle. Dorso-laterally to this on each side is a compact group of nerve cells, the dorsal motor nucleus i.e., group of neurone bodies) of the vagus. Ventrally to this and ventrolaterally to the fourth ventricle is another larger group of larger and more scattered nerve cells. This is the hypoglossal nucleus, the axones of which form the hypoglossal nerve. Note that while the cells of one hypoglossal nucleus present Nissl chromophilic bodies of normal appearance, those of the other nucleus appear pale and the cell bodies more rounded. Select one. of these cells showing also an eccentric nucleus. High power. Study the above cell, noting that it Is swollen, that its nucleus is eccentric and that the chromophilic bodies have disappeared from the interior of the cell leaving only a peripheral rim of these bodies (central chromatolysis). The nucleus does not show so much change but may appear paler than normal. Draw this and other cells showing variations. Some of the cells of the nucleus showing degenerative changes contain nuclei apparently centrally placed. How do you account for this? How can secondary degeneration be used in the study of the architecture of the nervous system? What does it tend to show as to the relations between neurones? What does it show as to the relation between neurone body and axone? 2. Transverse section of...