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ABSTRACT: Many attempts have been undertaken to make permanent preparations of helminth eggs. However, the resulting preparations either lacked durability or tended to deform thin-shelled eggs, such as those of the hookworm. To overcome these drawbacks, we have modified 2 aspects of the glycerin-jelly mounting procedure. First, we gradually changed the media in which the helminth eggs soaked, from 10% formalin via water to a 70% ethanol and 5% glycerin solution. It took 10 days, which is much longer than the time required for the processes previously reported. Second, we used a hole slide glass instead of a slide glass. Eggs of 11 species of helminths have been prepared with this procedure, and have kept their morphology without apparent change for more than 4 yr.
Preparations of helminth eggs are necessary for the teaching of parasitology and to use as references in clinical laboratories responsible for stool examination. The eggs are often fixed and preserved in 10% formalin, and a drop of suspension might be used to make a temporary wet mount whenever necessary. Because the eggs are lost on each occasion, repeated observations of the same eggs, even if they have any diagnostic features remaining, is generally impossible. It is also costly and time consuming. Despite attempts by many researchers to develop permanent preparations, success has not been realized in creating mounts that were durable but did not deform the eggs, especially eggs with thin shells, such as those of hookworms or Vampirolepis nana.
Our attempts were divided mainly into 3 approaches: (1) mount with a medium containing xylene (Fan and Mao, 1970; Berlin and Miller, 1980), (2) use glycerin-jelly (GJ) mounting procedures (Burrows, 1965), or (3) wet mount the eggs in 10% formalin as they are fixed and preserved, as in the turning cell mount (Burrows, 1965) and the double-cover-glass method (Garcia, 2001). In the procedures of Group 1, the eggs became deformed or ruptured when they were placed into high concentrations of ethanol solution, or into xylene. In Group 3, the eggs' morphology was well preserved until a fragile frame, which was made of varnish, and retained the formalin, broke in the turning cell mounts. The eggs became pressed and deformed between 2 cover glasses in the double-cover-glass method. Glycerin-jelly mounting...