On the nerve terminations in the selachian cornea / by Cresswell Shearer.

  • Shearer, Cresswell, 1874-
Date:
1898
Catalogue details

Licence: Public Domain Mark

Credit: On the nerve terminations in the selachian cornea / by Cresswell Shearer. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

    9/16 page 215
    the epithelium which could in any way answer to the various networks described by Klein (7). Klein states that the sub-epithelial network is situated beneath Bowman’s membrane and that he was able to remove the entire epithelium without disturbing this net-work. On examining a similar preparation from the dog-fish with the epithelium so removed no trace of this plexus is found, but in- stead we get a view of regular plexus of the corneal tissue proper (Fig. 4) so very different in appearance from the much larger nerves of the epithelium. This network, of which Fig. 4 is but a very poor represen- tation, is of the very finest texture, the fibers forming it being of the very finest in size, perfectly uniform throughout their course and at once to be distinguished from the nerves of the epithe- lium by the way in which they branch at right angles and their irregular course and all pretty much within the same plane. Every sheet of the corneal substance proper seems to have a special network of these fibers over it. When one network is within focus the the networks of the layers deeper can be faintly made out, and by properly adjusting up and down one-can bring nearly all the networks into view one after the other. One pe- culiarity of these nerve fibers is their sharply granular appear- ance as if made up of a series of closely arranged dots one af- ter the other in a delicate strand. These fibers in branching and winding about amongst the corneal cells do not keep any definite relation with them, and it is needless to say no anasto- moses with them or their processes was to be distinguished. As Dogiel has found in man, the nerve fiber never comes into real relation with the cell but simply passes over it or along one border. On comparing Fig. 4, with Fig. 7 of Dogiel’s (2) pa- per the general resemblances of this network in selachians and man is very apparent. There is a tendency in selachians to greater regularity of branching of the fibers at right angles, they run in one direction for a certain distance then abruptly turn and run at right angles to their former course, while in man the change of direction is less sharp and sudden.
    digitised image 1
    digitised image 2
    digitised image 3