Changes in gonadal development, androgenic gland cell structure, and hemolymph vitellogenin levels during male phase and sex change in laboratory-maintained protandric shrimp, Pandalus hypsinotus (Crustacea: Caridea: Pandalidae)
Most pandalid shrimps show protandric hermaphroditism, and male sexual differentiation is considered to be controlled by the androgenic gland. In the present study, we examined the histology of gonadal development during the male phase and sex change and the involvement of the androgenic gland in regulating male reproduction in laboratory-maintained Pandalus hypsinotus. Juvenile shrimps developed testicular tissues in the peripheral part of gonads during the age of 16–31 months and produced spermatozoa between 34 and 36 months. After reaching sexual maturity, male shrimps exhibited seasonal testicular development: active production of spermatozoa (February–May), disappearance of spermatozoa (spent, April–June), increase of spermatocytes (May–November), appearance of spermatids and spermatozoa in the gonads (November–February). The androgenic gland cells became larger and the rough endoplasmic reticulum in the cytoplasm developed at male sexual maturity. The cell structure shows that the androgenic gland hormone is a peptide. Furthermore, bilateral eyestalk ablation on immature male shrimps induced hypertrophy of the androgenic gland and acceleration of male sexual maturation. These results indicate the involvement of androgenic gland hormone and some eyestalk factor in regulating male sexual maturation. Over a 1-year laboratory-rearing period, some male shrimps (16.7%) changed sex. In transitional shrimps, testicular tissues in the gonads and androgenic glands degenerated; on the other hand, oocytes started yolk protein accumulation and hemolymph vitellogenin levels became high. These results suggest that androgenic gland degeneration is a trigger for sex change and that the vitellogenin level is a useful marker for sex change.
KeywordsTesticular Tissue Ejaculatory Duct Vitellogenic Oocyte Crustacean Hyperglycemic Hormone Male Phase
The present study was supported, in part, by a Fisheries Research Agency project, and by funds from the Cooperative Program No. 38, 2001 provided by Ocean Research Institute, University of Tokyo. The experiments comply with the current laws of Japan.
- Adiyodi RG (1984) Seasonal changes and the role of eyestalks in the activity of the androgenic gland of the crab, Paratelphusa hydrodromous (Herbst). Comp Physiol Ecol 9:427–431Google Scholar
- Aoto T (1952) Sexual phases in the prawn, Pandalus kessleri Czerniavski, with special reference to the reversal of sex. J Fac Sci Hokkaido Univ Ser 6 Zool 11:1–20Google Scholar
- Aoto T, Nishida H (1956) Effects of removal of the eyestalks on the growth and maturation of the oocytes in a hermaphroditic prawn, Pandalus kessleri. J Fac Sci Hokkaido Univ Ser 6 Zool 12:412–424Google Scholar
- Bergström BI (2000) The biology of Pandalus. In: Southward AJ, Tyler PA, Young CM, Fuiman LF (eds) Advances in marine biology, vol 38. Academic, London, pp 55–245Google Scholar
- Kurata H (1957) The biology of the prawn, Pandalus hypsinotus. Mon Rep Hokkaido Fish Exp Stn 14(2):42–51Google Scholar
- Murakami K (1986) Brood stock and hatchery of the coonstriped shrimp Pandalus hypsinotus. Saibaigiken 15:27–41(in Japanese)Google Scholar
- Murakami K (1992) Maturity cycle, and copulation and spawning behavior of rearing Pandalus hypsinotus. Saibaigiken 20:65–72(in Japanese) Google Scholar
- Nagamine C, Knight AW, Maggenti A, Paxman G (1980a) Effects of androgenic gland ablation on male primary and secondary sexual characteristics in the Malaysian prawn, Macrobrachium rosenbergii (de Man) (Decapoda, Palaemonidae), with first evidence of induced feminization in a nonhermaphroditic Decapod. Gen Comp Endocrinol 41:423–441CrossRefGoogle Scholar
- Okumura T, Hara M, Hara M, Okiyama M (1997) Possible roles of the androgenic gland in male reproduction in the giant freshwater prawn, Macrobrachium rosenbergii. In: Kawashima S, Kikuyama S (eds) Advances in comparative endocrinology, vol 1. Monduzzi Editore, Bologna, pp 73–77Google Scholar
- Sagi A, Khalaila I (2001) The crustacean androgen: a hormone in an isopod and androgenic activity in decapods. Am Zool 41:477–484Google Scholar
- Taketomi Y, Murata M, Imakado K (1996) On the androgenic gland of the crayfish, Procambarus clarkii: I. Seasonal changes in the cell structure of the androgenic gland of the crayfish, Procambarus clarkii. Mem Fac Gen Edu Kumamoto Univ Nat Sci 31:65–72Google Scholar