Development of gonads in plant and soil nematodes - a review

Abstract

The article describes the comparative gonad development among different nematode groups. The monoprodelphic gonad of female develops from a single primordium which is oriented parallel to the longitudinal axis. The development starts with proliferation of somatic nuclei posteriad while the germinal nuclei remain at the anterior end of primordium. In the didelphic secerncntea the gonad develops from a single primordium which may be longitudinally Oriented in tylenchs or obliquely oriented in some rhabditids and diplogasterids. In didelphic Adenophorea the gonad develops either from a single longitudinally oriented primordium (e.g dorylaims) or two primor-dia oblique in position with each other (e.g. mononchs). In Secernentean males the monorchic gonad develops as a result of anterior proliferation of somatic nuclei. The germinal nuclei thus remain at the posterior end. In diorchic condition which is exclusively found in Adenophorea the primordium elongates both in anterior and posterior direction to give rise to two opposed testes joined with a common vas deferens. The ventral hypodermal chord nuclei play an important role in gonad development. In females they form a part of vagina while in males they form the supplements. The spicules develop from the dorso-latcral aggregates of cells known as spicular primordia.