Worm Breeder's Gazette 2(2): 6
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
The post-embryonic lineages of both the hermaphrodite and the male gonads have been determined by direct observation in living worms. Although the adult male and hermaphrodite gonads are quite different from each other, their lineages have a number of common features. Both male and hermaphrodite gonads arise from a gonadal primordium consisting of four cells (named 1, 2, 3 and 4 from anterior to posterior). Two of these cells (1 and 4) are somatic, and two (2 and 3) are germ line precursor cells. In each sex, the lineage of the somatic cells proceeds according to a nearly invariant pattern with respect to the number of cell divisions, cell migrations, and the final fates of specific daughter cells. The lineage of the germ line cells is invariable. In each sex, the somatic precursor cells undergo an early period of cell divisions (late L1-early L2). These early divisions give rise to 10 cells in the male and 12 cells in the hermaphrodite. These cells do not divide again until early L3 when they divide extensively to generate all the cells present in the adult somatic structures. The hermaphrodite somatic structures include the anterior sheath, the anterior spermatheca, the uterus, the posterior spermatheca, and the posterior sheath. The male somatic structures include the seminal vesicle, and vas deferens. In the hermaphrodite, the quiescent period during L2 is characterized by a migration of the cells. The cells of the male migrate during the early period of cell division and simply grow larger during L2. In both males and hermaphrodites there seems to be a general rule that a clone of cells does not define a given structure. Instead, both cell 1 and cell 4 contribute some daughters to each structure. The anterior and posterior sheaths are the only exception since each is comprised exclusively of daughters of cell 1 (anterior) or cell 4 (posterior). Finally, there is an indication in the hermaphrodite lineage of an effect of position on the lineage pattern. At the L2-L3 stage in hermaphrodites the cells that will give rise to the ventral uterus and anchor cell assume one of two different configurations (3L or 3R). The cells follow one lineage pattern from the 3L configuration, and a different lineage from the 3R configuration. The two alternative lineages, however, give rise to equivalent structures.