VC.] CILIATED EPITHELIUM. 135 



LESSON VI. 

 CILIATED EPITHELIUM. 



Ciliated Epithelium occurs in the nasal mucous membrane 

 (except that of the olfactory region), the cavities accessory to the 

 nose, the upper half of the pharynx, the Eustachian tube, larynx, 

 trachea, and bronchi, the uterus (except the lower half of the cervix), 

 Fallopian tubes, vasa efferentia to lower end of epididymis, the 

 ventricles of the brain, and the central canal of the spinal cord. 



V. Ciliated Epithelium. A ciliated cell may be any shape, but 

 usually it is 4 more or less columnar. Only the cells of the super- 

 ficial layer bear cilia. The bunch of cilia are directly continuous 

 with the protoplasm of the interior of the cell, and are planted on a 

 clear disc, which is said to be composed of small "knobs " placed side 

 by side to form a bright refractile disc ; a cilium being attached to 

 each knob. The deeper cells may be pyriform or polyhedral, accord- 

 ing to the situation from which the epithelium is obtained. Goblet- 

 cells may be found between the superficial ciliated cells. 



1. Ciliary Motion in the Frog (H). After pithing a frog, gently 

 scrape the roof of its mouth with a scalpel, and diffuse the scraping 

 in a drop of normal saline, add a short piece of hair, and cover. 



(a.} Notice groups of cells with cilia on their free surface. The 

 cilia bend quickly, at the rate of ten to twelve times per second, with 

 a whip-like motion in one direction, and then rapidly unbend, thus 

 creating currents in the liquid, and thereby moving the corpuscles, 

 granules, or other free particles that may be present. They bend 

 more rapidly in one direction than the other. All the cilia covering 

 one surface are not in motion at one time, but the movement passes 

 from cell to cell in a wave-like form. If a portion of cell with cilia 

 attached is in view, the fragment of the cell may be seen to be 

 moved in a definite direction by the vibratile motion of its own 

 cilia. Cilia detached from a cell cease to move. 



2. Ciliary Motion in the Mussel (L and H). Open a salt-water 

 mussel, collect the salt w r ater which escapes, cut out a fragment of 

 one of the flattened yellow gills, and place it in a drop of salt water. 

 By means of two needles separate slightly the bars which compose 

 the gills, cover and examine. 



(a.) (L) Observe the bars with their free rounded ends and their 

 surfaces beset with a fringe of moving cilia, which cause the particles 

 suspended in the fluid to be carried along in a definite direction. 



