Kinetics of the cercaria-schistosomulum transformation in vivo

Abstract

Recently, the transformation of Schistosoma mansoni cercaria into schistosomulum have been investigated by several workers, mainly in relation to the immunological and biochemical aspects. A t first glance a logical conclusion from the facts available is that various modification steps occur during the transformation of a cercaria (a free living larva adapted to a freshwater environment) to a schistosomulum (an organism newly adapted to the host conditions).Various methods for collecting living schisto somula have been described and the larvae have been recovered both in vitro and in vivo. The basic differences between cercaria and schistosomulum were established by Stirewalt1** 20 Additional differences were subsequently reported^ 3 9 11 12 22 23 24 These differences are the standard criteria by which the organisms recovered by in vitro methods can be considered to be schistosomula.

Schistosoma mansoni: inflammatory foci around larvae in the peritoneal cavity of naive mice is radiosensitive

“…The larvae were collected by washing the peritoneal cavity with saline, and were concentrated by centrifugation as described previously 14 . The recovered larvae were resuspended in 1 ml of saline solution and examined under a dissecting stereomicroscope.…”

“…The mean percentage (standard deviation) of larvae with or without adhered cells was calculated. Cells and parasites obtained from each peritoneal cavity were used to prepare smears and some of them received drops of 0.1% neutral red solution or were stained by Giemsa or Wrigth' s stains 14 .…”

Phenotypic plasticity of maleSchistosoma mansonifrom the peritoneal cavity and hepatic portal system of laboratory mice and hamsters

“…As an advantage, peritoneal infection allows a simple and rapid method for mass screening of prophylactic agents to combat schistosomiasis (Pereira et al, 1974). This method of study has also helped to elucidate aspects of the early stages and immunology of the host-parasite relationship (Melo et al, 1978(Melo et al, , 1993a(Melo et al, , b, 1994, 1985Chao et al, 1986). Indeed, it has been demonstrated that parasites recovered from the peritoneal cavity of two albino mouse strains (AKR/J and Swiss) are significantly different in relation to the total body length of the worms, the intraperitoneal worm burden and the maturation degree of the schistosomes (Bicalho et al, 1993).…”