Neuroendocrine regulation of reproduction in crustaceans with emphasis on ovarian maturation in Macrobrachium rosengergii (de man).

Abstract

Moulting (shedding of exoskeleton for growth) and reproduction (production of gametes) are the two major important events in the life of Crustacea. Reproduction in this Class of invertebrates is under the dual control of inhibitory action by eyestalk hormone (GIH/VIH) and stimulatory control by brain and thoracic ganglia (GSH/VSH). Moulting is controlled by the inhibitory hormone (MIH) from eyestalk (sinus gland complex) and moulting hormone (ecdysone) elaborated from Y-organ. Both the events employ complex interactions of the various hormones, neuropeptides, biogenic amines, enkephalins etc. The most critical input in the rapidly expanding aquaculture industry is the availability of good quality seed for which proper understanding of reproductive physiology of the candidate species is essential. An attempt has been made to document the recent advances in the neuroendocrinology of ovarian maturation in the commercially important species of Crustacea which are having potential role in development and expansion of aquaculture. Different types of neurosecretory cells in the eyestalk, brain (supraoesophageal) and thoracic ganglia of the female M. rosenbergii were mapped and the correlative changes in the neurosecretory cells during ovarian maturation recorded. Effect of unilateral eyestalk ablation on ovarian development as well as the neurosecretory cells of brain and thoracic ganglia of the female giant freshwater prawn were recorded to judge their secretory activity. The active state of neurosecretory cells was characterized by hypertrophy, increase in number of nucleolus, staining intensity, granulation and migration of secretory material towards the axons. Histochemical tests indicated that the neurosecretory cells were strongly positive to acid fuchsin, paraldehyde fuchsin but also exhibited feeble reaction in Sudan black B and periodic acid-Schiff (PAS) reagent.