Worm Breeder's Gazette 1(2): 7

These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.

Cracking Nematode Eggs

A.F. Bird

Although eggs may be opened chemically by treatment with various 
proteolytic enzymes, these methods are not suitable where studies on 
the shell and its associated membranes are concerned.  Some nematode 
eggs are particularly impervious to chemicals, including fixatives.  
Under these circumstances physical methods have to be used.  
Ultrasonic disintegration is too vigorous and destroys the egg 
contents and the innermost 'lipid' layer of the egg shell.  I have 
found that attempts to pierce a small area of shell using micro-
manipulated glass needles is tedious and unsatisfactory (perhaps a 
fine laser beam would be ideal).  A simple and inexpensive method for 
cracking shells is to fix the eggs in phosphate buffered 3% 
gluteraldehyde at 45 C for 30 min, place the eggs in fresh fixative at 
room temperature in a solid watch glass, place several eggs close 
together on the curved surface of the watch glass and cover them 
gently with a piece of cover slip, gentle pressure on the center of 
the surface of the cover slip with a needle will cause the eggs to 
flatten slightly.  By altering this pressure the eggs can be 
alternately compressed and released until one or two crack and part of 
their contents may extrude.  Provided that some uncracked eggs remain 
in the group of eggs so treated, the degree of physical damage to the 
cracked eggs appears slight and the method leads to good fixation of 
larval contents or egg shell some distance from the cracked area.
A much lower temperature than that suggested above for fixation of M.
javanica prior to cracking may suffice for C.  elegans without 
resulting in gross extrusion of fluid contents during the cracking