a1 Department of Zoology, University College, P.O. Box 78, Cardiff CFI IXL, Wales, U.K.
Vitelline gland development and incomplete parthenogenesis in 65-week-old female Schistosoma mansoni from single sex infections is described. Vitelline gland development was restricted to the extreme posterior end of each worm and the developed vitelline lobules showed the normal sequence of development and maturation. The ovary, however, was always in an immature state. Egg production occurred although the eggs were non-viable.
The results suggest that, whilst male stimulation is not necessary to initiate vitelline gland development and egg production, it appears to be essential for the complete maturation of the ovary. The possible importance of ovarian maturation to the production of viable eggs is discussed.
(Accepted December 17 1986)
* Present address and address for all correspondence: International Laboratory for Research on Animal Diseases, P. O. Box 30709, Nairobi, Kenya.