THE IN-VITRO DEVELOPMENT OF THE PENTASTOMID POROCEPHALUS-CROTALI FROMTHE INFECTIVE INSTAR TO THE ADULT STAGE

The in vitro development of the pentastomid Porocephalus crotali from the infective, seventh (VII) instar, dissected from the tissues of rat intermediate hosts, to the adult male (X) and female (XI) instars, no rmally resident in the lung of rattlesnake definitive hosts, is descri bed. The culture medium comprised washed human blood cells, resuspende d in bovine serum (50:50, v/v), with 20 % minimum essential medium and antibiotics. Two batches of approximately 100 pentastomids, maintaine d at a density of 2 worms/ml, were cultured in 500 ml bottles in an at mosphere of 5 % CO2 in air at 28 degrees C. Culture bottles were rotat ed slowly on a Rollacell system and the medium was replenished every 2 -3 days. Growth was monitored at various intervals by weighing worms, measuring cast cuticles with attached moulted hooks recovered from the medium, and by dissecting worms for measurements of various organ sys tems. Three moults separated the infective and adult male instar, wher eas 4 moults were necessary in the case of females. In both cultures n atural mortality was about 10 % over a 160-day period, by which time 3 3-51 % of females and 62-70 % of males had reached the terminal instar . Some males attained full sexual maturity with seminal vesicles loade d with viable sperm: such males were indistinguishable from males reco vered from naturally infected rattlesnakes. However, females never ach ieved full size, even after 200 days, and although copulation did not occur in vitro, some females became patent.