ScienceAsia 16 (1990): 167-176 |doi: 10.2306/scienceasia1513-1874.1990.16.167

HISTOCHEMICAL LOCALIZATION OF ACETYLCHOLINESTERASE ACTIVITY IN NEURAL TISSUES OF THE GIANT FRESHWATER PRAWN, Macrobrachium rosenbergii DE MAN

KOSUM CHINSETHAGID,^a SUPAPORN AJPRU,^a BOONSIRM WITHYACHUMNARNKUL,^a CHAITIP WANICHANON^a AND BOONSERM POOLSANGUAN^b

ABSTRACT: The optic lobe, optic peduncle, brain and thoracic ganglion of the giant freshwater prawn, Macrobrachium rosenbergii de Man, were examined for the presence of specific acetylcholinesterase (AChE) by a histochemical technique. Neurons and axons containing AChE were detected in all the tissues studied. AChE-positive neurons were found in the medulla externa and medulla interna of the optic lobe; they were small monopolar neurons whose axons running proximally toward the optic peduncle. These axons, which also showed positive reactions for AChE, were detected in the medulla externa, medulla interna and optic peduncle, but not in the medulla terminalis. AChE-positive axons were seen as dark brown precipitate on axolemma along the width of the axons. In the optic peduncle, positive staining on axons was spared at intervals along the length of the axon fibers. A few small neurons and several nerve fibers in the brain were stained positively for AChE. The nerve fibers were of smaller width when compared to those of the optic peduncle. Regional distribution of AChE-positive fibers was also observed in the brain. Several nerve tracts in the thoracic ganglion were AChE-positive with dark brown precipitate along the axolemma, but without a characteristic sparing pattern as seen in the optic peduncle. The size of the axons were the same as that of the optic peduncle.

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a Department of Anatomy and b Department of Biology, Faculty of Science, Mahidol University, Rama 6 Rd., Bangkok 10400, Thailand.

Received 19 November 1990