Age-related changes in Heligmosomoides polygyrus (Nematoda): neutral lipid content in developing oocytes

Abstract

Changes in neutral lipid content of developing female gametes in Heligmosomoides polygyrus at 8, 12, 20, 40, 80, and 140 days postinfection (p.i.) were investigated and correlated with egg production by the worms over the same period. Egg production increased to day 20 p.i. when the average egg output for one female reached approximately 700 eggs/day. A decline in egg production occurred from 80 days p.i. until the end of the experiment (140 days p.i.). Neutral lipid content was low in oogonia from worms of all ages. Developing oocytes contained the highest levels of neutral lipid. There was a significant loss of lipid just before fertilization of the oocytes. An increase in lipid occurred in all developmental stages of gametes from day 8 to day 40 p.i., and a significant decline occurred thereafter to day 140 p.i. Although egg production and lipid content of the female reproductive tract showed similar trends, there was not a precise correlation. It is felt that nuclear and cytoplasmic processes other than lipid anabolism or catabolism within the developing gametes play a more important role in influencing egg output.