Worm Breeder's Gazette 3(1): 18a
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
The phasmid is a sensilla in the tail analogous to the amphids in the head and probably functions as a chemosensory receptor. Like most sensillae it is apparently attached to the hypodermis by a specialized cell, the socket cell. The phasmid socket cell is derived from the T. seam cell after 3 rounds of division that occur in the first larval stage. The sister of the socket cell differentiates into a cell of unknown function which has been nick-named the 'wing' cell. In the hermaphrodite the lineage of the socket cell is T.Paa, whereas the wing is T.PaP. In the male these allocations are reversed. A male and hermaphrodite were fixed and sectioned in L2 lethargus to try to find out the reason for this reversal. It was found that at this stage (i.e. about 5 hours after the socket and wing had been born) both these cells looked like socket cells, one being concentric to the other, both in the hermaphrodite and in the male. Thus it seems that soon after birth these two cells are equivalent and that in the course of development one gets transformed into a wing cell; either may be chosen to do this depending on the sex of the animal. A further animal was fixed about 5 hours after hatching (i.e. before the T. cell had divided) and reconstructed. It was found that in this case the posterior part of the T. seam cell was functioning as a socket cell. The socket and wing cells are ultimately derived from the posterior daughter of the first division of the T. seam cell so that it seems that this differentiated function is propagated through the lineage.