Development of the incretory organs in the eyestalk of freshwater prawn,Macrobrachium kistnensis

Abstract

The development of the neurosecretory cells in eyestalk is studied in zoea, juvenile and adult stages of theMacrobrachium kistnensis. In zoea, the ganglionic mass of the eyestalk compreses of three parts viz. medulla externa, medulla interna and medulla terminalis. The future sensory pore x-organ is characterized by onion bodies near medulla terminalis and a vacuole closely applied to the outer surface of the eyestalk. The monopolar giant neuron is observed in zoea. In juvenile prawn, in addition to zoeal features the sinus gland makes its appearance. At this stage, neurosecretory cells are discernible in the medulla externa and terminalis. In adults, the eyestalk presents well developed lamina ganglionaris, medulla externa ganglionic x-organ (m.e.g.x.), medulla interna ganglionic x-organ (mi.g.x.) and medulla terminalis ganglionic x-organ (m.t.g.x.).