Chromosome complement, gametogenesis, and development of Strongyloides stercoralis

Gametogenesis and development were studied in free-living adults of the human parasitic nematode Strongyloides stercoralis. The diploid chromosome number is 6 in germ-line tissue of females and in embryos that will develop into parasitic females. Reproduction appears to be by meiotic parthenogenesis and pseudogamy, as in other species in the genus. Fecundity may be limited by the short lifespan of males. Newly hatched larvae contain about 500 cells, whereas adult females have about 840 somatic cells and a variable number of germ-line cells. The apical vegetative zones of both ovary and testis are occupied by cells with large amounts of DNA in their nuclei.