Further observations on the B-type neurosecretory cells in the thoracic ganglion of the crab, Potamon magnum magnum (Pretzman).

Only four types of the secretory neurones were observed in the thoracic ganglion of the fresh water crab, Potamon magnum magnum (Pretzman). These cells are classified as A, A', B and C types. Our results also confirmed that the B and B' types of cells (BAID et al. 1968) are one and the same type, the B cells. The B cells are of two forms, with and without the axons. They clearly showed sequential histological patterns pointing out to their phases. The secretory material is discharged either through the periphery or through the axon and periphery both. The vacuoles were observed in both the forms of the B cells. The remarkable sign of the activity of the nuclear membrane especially at the beginning of the secretory cycle and the appearance of the first secretory granules around the nucleus strongly support the vital role of the nucleus in the initiation of the secretory cycle.