VI. The effects of the age, sex and species of the host on worm growth
Published online by Cambridge University Press: 06 April 2009
Adults of Nematospiroides dubius recovered from female mice were smaller than those from male mice. In general, a similar result was obtained for infections in rats. Longer worms were recovered from gonadectomized rats than from intact animals; the difference between the growth of the worms in male and female hosts was still apparent.
Treatment of castrate male rats with testosterone was more favourable to the growth of the male than the female worm. Oestradiol treatment of spayed female rats caused a stunting of both sexes of the nematode. However, this effect was least noticeable among the female worms.
An increase in the age of the rat resulted in a decrease in the lengths of the worms recovered. The worms grew to greater lengths in 25-day-old mice than in rats of the same age and sex.
It is suggested that the sex hormones may have two effects on worm growth. First, an indirect effect involving the nutrition of the worm, and secondly, a direct effect of the hormones themselves on the tissues of the worm.
This work was done during the tenure of a Department of Scientific and Industrial Research Studentship. My thanks are due to Dr E. T. B. Francis for his help and criticism, and to Professor I. Chester Jones, in whose department the work was done, for the facilities he provided.