Mucosal larval recovery techniques of cyathostomes: can they be standardized?

The methods used currently for enumeration of mucosal stages of cyathostome s include transmural illumination (TMI) and peptic digestion (DIG). Enumera ting the inhibited early L3 (EL3) and differentiating between mucosal devel oping L3 (DL3) and L4 (ML4) is only possible when DIG is used, However, in some studies higher numbers of DL (DL3 + ML4) have been found when using TM I as opposed to BIG. This finding, however, is not consistent. Moreover, re sults are not consistent when DIG and TMT are compared for treated and cont rol groups of horses in drug trials. Studies performed on the effect of fre ezing on DIG and TMI also show inconsistent results between laboratories. H owever, there is, evidence that digested samples can be preserved in 5-10% formalin or in 70% ethanol when used as a buffered isotonic solution. Based on these results it is premature to recommend standardized mucosal larval recovery techniques. Consequently, TMI and DIG should both be applied. Reco mmendations for further research for the development of standardized techni ques are given. (C) 1999 Elsevier Science B.V. All rights reserved.