Histomorphology of the Neurosecretory Cells of Eyestalk, Brain and Thoracic Ganglia of Female Giant Freshwater Prawn, Macrobrachium RosenbergII

Abstract

Histomorphology of the neurosecretory cells of eyestalk, brain and thoracic ganglia of Macrobrachium rosenbergii were recorded. There were five types of neurosecretory cells (NSCs) in eyestalk having size range of 5 - 35 um, shape varied from round to oval. The cells were distributed in medulla externa, medulla interna and medulla terminalis. Sinus gland measuring 30-35 um was located in medulla interna. Axonal terminals of the neurosecretory cells were found to terminate in this structure. Brain and thoracic ganglia possessed five types of neurosecretory cells such as giant neuron (>80 um), A (60-80 um), B (40-60 um), C (20-40 um) and D (<20 um). They were seen arranged in several groups in different parts of brain. While B, C and D cells were localized in anterior region, giant neurons and A cells dominated in posterior region. In lateral regions A, B, C and D cells were distributed. The thoracic ganglia could be divided into anterior, middle and posterior regions. NSCs were distributed in anterior and posterior portions but were lacking in middle part. A and B cells were present in anterior regions followed by C and D cells. In posterior region, giant neurons and A cells were present. Histochemical tests demonstrated the neurosecretory cells of the prawn to be strongly positive for acid fuchsin, aldehyde fuchsin and paraldehyde fuchsin and also exhibited feeble reaction to Sudan black B and periodic acid-Schiff (PAS) reagent.