Fig. 1.

Smed-nanos is expressed in the testes and the ovaries of juvenile and mature S. mediterranea hermaphrodites but not in young hatchlings. (A) Diagram of S. mediterranea hermaphrodite illustrating the reproductive organs. o, ovaries; t, testes; od, oviducts; ca, copulatory apparatus. (B) Whole-mount in situ hybridization showing nanos expression in testes (arrowheads); expression is not detected in newly hatched animals. From Top to Bottom: hatchling (34 of 38 lacked detectable Smed-nanos mRNA), juvenile (n = 4), smaller (n = 5), and larger mature worms (n = 11) (dorsal views). (C) Ventral views of the worms in B, showing nanos expression in the ovaries (arrowheads). (Scale bars, 1 mm.)