Chitin synthesis in zygotes of Ascaris suum.

In Ascaris suum chitin is formed in the zygote immediately after oocyte fertilization, and its synthesis is completed in the eggs from the distal half of the uterus. Incorporation of radiocarbon [14C] glucose into chitin of the eggshell was 40-fold higher than incorporation of [14C] glucosamine. The same rank order also holds for the incorporation of label from these isotopes into the glycogen of the ovaries. A large part of the radiolabel was incorporated first into oocyte glycogen and only after fertilization was it incorporated into eggshell chitin. Actinomycin D inhibited chitin synthesis in the eggs from the distal half of the uterus and it significantly reduced incorporation of radiocarbon from glucose into chitin.