gonad morphology variant pachytene progression during oogenesis variant pachytene region organization variant Animals exhibit variations from control animals in the organization of the germ cell nuclei in the pachytene stage region of the gonad. In C. elegans the pachytene region begins just proximal to the germline's transition zone, where germ cells coordinately switch into the leptotene/zygotene stage from the premeiosis stage (WormAtlas). C_elegans_phenotype_ontology WBPhenotype:0001951