Persistence of Reduced Androgenic Glands after Protandric Sex Change Suggests a Basis for Simultaneous Hermaphroditism in a Caridean Shrimp.

The caridean shrimp Lysmata wurdemanni is a protandric simultaneous hermaphrodite. These individuals go through a male phase (MP) before changing sex to become female-phase simultaneous hermaphrodites (FPSH). The latter have an externally female phenotype, but retain a reduced male reproductive system and both male and female reproductive function. Previous studies have reported that the androgenic glands (AGs), whose hormones stimulate development of male characteristics in decapod crustaceans, are absent in the female phase of purely protandric species. We tested the hypothesis of androgenic gland persistence in FPSHs of L. wurdemanni by dissection and histology on the ejaculatory ducts. These glands were observed in FPSHs, although in a variably atrophied form. Androgenic glands of L. wurdemanni MPs are compact and replete with well developed cells, with large, deeply stained (hematoxylin-eosin) nuclei, as in males of gonochoric and protandric species. The AGs of simultaneous hermaphrodites were more reticulate in appearance due to the apparent breakdown and loss of cells, resulting in vacuolated areas, or empty spaces in the gland surrounded by connective tissue fibers or cell remnants. However, all FPSHs possessed numerous, or at least some possibly functional cells. The greatest atrophy of AGs was observed in the largest (i.e., oldest) FPSHs. However, the ovotestes of all FPSHs retained a small testicular portion with well developed ejaculatory ducts containing sperm. Our results suggest that the reduced androgenic glands of female-phase simultaneous hermaphrodites of L. wurdemanni allow them to maintain male reproductive function after sex change.