Sinus Gland Extirpation in the Crayfish Without Eyestalk Removal

Abstract

In view of the increasing volume of literature pertaining to endocrine activities of the crustacean sinus gland, it is unfortunate that the only simple and sure method of removal of these glands from the body has involved the removal of the total eyestalk. The eyestalk constituting the most important light receptor of the organism, contains, in addition to the sinus gland, several important nerve ganglia, the x-organ, and other possible endocrine sources. For this reason the usual removal of so much additional tissue with the glands leaves the interpretation of the results of eyestalk removal somewhat uncertain, to say the least. Furthermore, such a function as control of retinal pigment migration, which is believed by a number of endo-crinologists to be normally under the control of the sinus gland, has not yet been confirmed by such a crucial experiment as gland extirpation since this latter has also always involved removal of the effector mechanism as well. Nearly every recent investigator in crustacean endocrinology has at one time or another attempted to remove the sinus gland while leaving the rest of the stalk intact. The only published attempt to date 1 dealt with the highly transparent shrimp, Palaemonetes. The technic developed in this case was not sufficiently satisfactory to be used as a routine laboratory method, and furthermore could not be used successfully upon the great majority of crustaceans whose exoskeletons were relatively opaque.

The simple technic described below has been devised to extirpate the sinus glands from crayfishes without eyestalk removal, and, in fact, with little apparent disturbance to the remaining functions of the stalk including vision. The operation can be performed rapidly, and after a little practice, bilateral extirpation of the glands in an animal can be accomplished in less than 5 minutes.