Fixing coccidian oocysts is not an adequate solution to the problem of preserving protozoan type material.
Fresh (36 days old) sporulated oocysts of Eimeria nieschulzi were divided into 7 groups. Control oocysts were maintained at 23 C in 2% aqueous (w/v) K2Cr2O7. The 6 experimental groups were mixed with either Bouin's solution, 10% aqueous (v/v) buffered formalin, Karnovsky's solution, glutaraldehyde, paraformaldehyde, or 70% aqueous (v/v) ethanol (EtOH). After 115 days, oocysts from all 7 groups were examined under oil immersion to determine the effect of fixation on their structural integrity. The parameters examined were lengths and widths of oocysts and sporocysts, percent sporulation (%S), and percent crenation (%C) of oocysts and sporocysts. The highest destruction (%S and %C) occurred in oocysts exposed to glutaraldehyde and Karnovsky's fixatives where 100% of both oocysts and sporocysts crenated and only 8% and 48%, respectively, remained sporulated. Of the oocysts in paraformaldehyde, 93% remained sporulated, but 95%of these oocysts and 100% of the sporocyst crenated. In Bouin's solution, 75% of the oocysts were intact structurally, but of these, only 60% were still sporulated with 70% of their sporocysts crenated. Oocysts preserved in 70% EtOH were 80% intact and 70% remained sporulated, but nearly 60% of their sporocysts collapsed even though the oocyst walls were intact. Oocysts preserved in 10% buffered formalin maintained structural integrity but had lower numbers of sporulated oocysts (84%) and greater numbers of crenated oocysts (18%) than control oocysts maintained in the dichromate solution (95% and 0%, respectively).
Duszynski
D W
DW
Department of Biology, University of New Mexico, Albuquerque 87131.
Gardner
S L
SL
D000085:Acetates / Q000494:pharmacology; D019342:Acetic Acid; D000818:Animals; D004539:Eimeria / Q000033:anatomy & histology / Q000187:drug effects*; D000431:Ethanol / Q000494:pharmacology; D005404:Fixatives / Q000494:pharmacology*; D005557:Formaldehyde / Q000494:pharmacology; D005976:Glutaral / Q000494:pharmacology; D010851:Picrates / Q000494:pharmacology; D011108:Polymers / Q000494:pharmacology; D011309:Preservation, Biological
D000085:Acetates; D005404:Fixatives; D010851:Picrates; D011108:Polymers; D005557:Formaldehyde; C026239:Bouin's solution; D000431:Ethanol; D019342:Acetic Acid; D005976:Glutaral; C003043:paraform