CRYOPRESERVATION OF SHEATHED 3RD-STAGE LARVAE OF GAIGERIA-PACHYSCELIS(SANDVELD HOOKWORM)

A technique for the cryopreservation of third stage larvae of Gaigeria pachyscelis is described. It consists of incubating sheathed third-st age larvae in 80% (v/v) ethylene glycol as a cryoprotectant for 30 s a t 0 degrees C, prior to transfer into liquid nitrogen. The survival ra te, as assessed by motility, was 37,6% after 30 d cryopreservation. A sheep infected percutaneously with 700 live cryopreserved third-stage larvae, harboured 41 adult worms (infectivity rate: 5,8%) when necrops ied 78 d later.