Neural and Chemical Control of Ciliated Epithelium.

Abstract

Practically all workers upon ciliated epithelium have denied that it possesses a nervous control. It is generally held that this type of contractile tissue possesses the property of automaticity, like the heart, digestive organs, urinary bladder, etc., but that, unlike these viscera, it is independent of neural domination. Textbooks of physiology usually omit the question of control in discussing this tissue, and sometimes ignore the subject of ciliated epithelium altogether. Parker and others 1 , 2 hold that nervous control of ciliated epithelium is extremely improbable. The histological features of this type of epithelium have been intimately worked out by histologists. A beautiful mechanism, apparently for inter-epithelium coordination, has been described by Grave and Schmidt. 3 Agersborg 4 has recently noted nerve fibers extending from the pedal ganglion (of Melibe) to the base of the ciliated columnar epithelium of the ectoderm of the foot. Merton, 5 working on fresh water snail, has recently given evidence for nervous control of ciliated epithelium in this lower form. The weight of authority is, however, decidedly against the view that ciliated epithelium is controlled by means of regulatory nerves.

We have performed many experiments which we believe show conclusively that ciliated epithelium in the vertebrate is definitely under the control of the nervous system. We believe our experiments show just as conclusively that ciliary movement is also subject to chemical control.

For most of this work, we studied the action of ciliated epithelium in the mouth and pharynx of the frog. Our method was as follows: The time in seconds in which this epithelium propelled a particle of cellulose across the field of a (binocular microscope was established as a speed norm. Then the rate of travel of the same particle across the same field was determined during and following the stimulation by various methods of the sympathetic and parasympathetic nerves supplying the pharynx.