SOME OBSERVATIONS ON THE DEVELOPMENTAL BIOLOGY OF CEPHALOBUS PARVUS (NEMATODA: CEPHALOBIDAE)

Abstract

Cephalobus parvus reproduced by parthenogenesis and females laid elongate smooth shelled eggs, measuring 45-55x20-30 µm. Freshly laid eggs were in single celled condition. Total embryonation period was 14-16 hr. The genital primordium of first stage juveniles showed a bulge on the dorsal wall. The division of germinal nucleus in the genital primordium started in the second moulting; prior to that only somatic nuclei divided. The primordium elongated anteriorly and formed the flexure of the ovary while elongation in the posterior direction resulted in the formation of the post-uterine sac. The multiplication of primordial nuclei became rapid in the fourth stage.