Abstract
In the brain of the brown dog tick, Rhipicephalus sanguineus (LATREILLE) 15 groups of neurosecretory cells are divided into 2 types, β and α cells. Among β cells, the function of the groups 2-5 in the dorsal ganglion are correlated with ecdysis, whereas group 18 in the ventral ganglion is required for the normal development of most tick tissue. Cells of groups 6, 72 and 71 (α-cell), 8-9, 10, 11, 12, 13, 14, 15, 16 and 17 are possibly related to digestion and maturation of the reproductive system respectively. The granules of β cells can be further divided into 2 groups by electron microscopy: large opaque droplets 1200Å-3000Å in diameter, and small opaque droplets 400Å-700Å in diameter. Lucent vesicles are also found.
