ScienceAsia 19 (1993): 001-024 |doi: 10.2306/scienceasia1513-1874.1993.19.001

GENERAL ANATOMY AND HISTOLOGY OF THE NERVOUS SYSTEM IN ACHATINA FULICA

MALEEYA KRUATRACHUE,^a E. SUCHART UPATHAM,^a VIYADA SEEHABUTR,^b JITTIPAN CHAVADEJ,^b PRAPEE SRETARUGSA,^b AND PRASERT SOBHON^b

ABSTRACT: The nervous system of Achatina fulica is composed of 13 ganglia: a pair of buccal ganglia, a pair of cerebral ganglia, a pair of pleural ganglia, a pair of parietal ganglia, a pair of pedal ganglia, a pair of tentacular ganglia and a single visceral ganglion. All ganglia give rise to many nerve branches which supply the snail body. They are surrounded by two layers of connective tissues: the thick outer layer and the thin inner layer connective tissue. Within the ganglia, there are nerve cells or ganglionic cells of four sizes: (1) the small cells which have the diameter of <20 microns, (2) the medium-sized cells which have the diameter of 20 - 39 microns, (3) the large cells which have the diameter of 40 - 99 microns, and (4) the giant cells which have the diameter of > 100 microns. In addition, there are masses of very small cells or globuli cells which have the diameter of 5 - 7 microns in the cerebral ganglia and the tentacular ganglia. Furthermore, in the cerebral ganglia, there is a group of neurosecretory cells which are characterized by a round heterochromatic nucleus and a large vacuole. Similarly, neurosecretory cells or collar cells were found around the finger-like projections of tentacular ganglion. These cells contain small round nuclei and their cytoplasm is full of granules and droplets.

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a Department of Biology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
b Department of Anatomy, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.

Received November 5, 1992