Journal of Environmental Biology

Changes in neurosecretory cells of eyestalk, brain and thoracic ganglia of female giant freshwater prawn, Macrobrachium rosenbergii,  in relation to gonadal maturation

 

A.K. Pandey and Anjani Kumar

Central Institute of Freshwater Aquaculture, Kausalyaganga, Bhubaneswar-751 002, India

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(Received: 30 March, 2004 ; Accepted: 25 October, 2004)

 

Abstract: Histomorphological changes in neurosecretory cells of eyestalk, brain and thoracic ganglia of Macrobrachium rosenbergii during different stages of ovarian maturation were recorded. There were five types of neurosecretory cells (NSCs) in eyestalk having size in range of 5-35 mm with or without axons. They were distributed along medulla externa, medulla interna and medulla terminalis. Axonal terminals of these neurosecretory cells were found to terminate in sinus gland. Brain and thoracic ganglia possessed five types of neurosecretory cells such as giant neuron (>80 mm), A (60-80 mm), B (40-60 mm), C (20-40 mm) and D (<20 mm). They were seen arranged in several groups in different parts of brain - in anterior region B, C and D cells were observed, in posterior region giant neurons and A cells dominated while in lateral regions A, B, C and D cells were recorded. Thoracic ganglionic mass was divided into anterior, middle and posterior regions. NSCs were distributed in anterior and posterior portions but were lacking in middle portion.  A and B cells were present in anterior-most region followed by C and D cells.  In posterior-most region, giant neurons and A  cells were present. The present study suggests that ovarian maturation in the giant freshwater is controlled by the secretion of B and C cells of eyestalk, giant neuron (GN), A and B cells of brain and thoracic ganglia.The  neurosecretory cells of eyestalk were active in immature stage whereas cells of brain and thoracic ganglia were active in mature stage. The active stage of secretion was characterized by hypertrophy, increase in number of nucleolus, staining intensity, granulation and migration of secretory material towards axons. Histochemical tests demonstrated that the neurosecretory cells were strongly positive to acid fuchsin, paraldehyde fuchsin but exhibited feeble reaction to Sudan black B and periodic acid-Schiff’s reagent (PAS).

 

Key words: Eyestalk, Brain, Thoracic ganglia, Ovarian maturation, Macrobrachium rosenbergii.

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