Masculinization of female Macrobrachium rosenbergii (de Man) (Decapoda, Palaemonidae) by androgenic gland implantation

Abstract

Sexually immature and mature female Macrobrachium rosenbergii (de Man) were implanted with vas deferens, testicular, or androgenic gland tissues. Females implanted with vas deferens or testicular tissue developed normally. In contrast, androgenic gland implantation masculinized 81% of female recipients. The first morphological evidence of masculinization was usually differentiation of appendixes masculina. Male gonopore complexes were developed by three sexually immature females and mature male chelipeds were developed by six large masculinized females. Females that were sexually immature at masculinization, i.e., those lacking brood chambers and reproductive setae, did not develop these structures. Females that were sexually mature at masculinization still evidenced brood chambers and reproductive setae at the termination of the experiment. All masculinized females retained their female gonopores. Internally, all but one masculinized female possessed bilaterally formed vasa deferentia. In females possessing male gonopore complexes, the vasa deferentia were completely formed. In the other masculinized females, the vasa deferentia were incompletely formed and existed as autonomous growths along the cephalothorax wall. Two masculinized females initiated spermatogenesis in their ovaries. Spermatogenic lobules were generally better developed in the anterior region of the ovaries. Oogenesis was still present but the oocytes never completed vitellogenesis. In remaining masculinized females, no evidence of spermatogenesis was found. Oogenesis was present but, as in females that had initiated spermatogenesis, the oocytes never completed vitellogenesis. The present results are comparable to past results of androgenic gland implantation experiments and support our hypothesis that the androgenic glands function similarly in the Amphipoda, Isopoda, and Decapoda.