NB 4-3:

NB 4-3 delaminates during S5.

There is no information about the lineage derived from NB 4-3 from other insects.

NB 4-3 expresses huckebein (hkb) and seven-up-lacZ (svp-lacZ) as it forms (Chu LaGraff et al, 1995; Broadus et al, 1995). Recent work has shown that it also expresses muscle-specific homeobox gene 1 (msh) and Klumpfuss (Klu) at S5 as well (Buescher et al, 1996; Isshiki, et al, 1997; Yang, et al, 1997).

Schmidt et al. (1997) described this lineage as containing 8-13 neurons, including many motoneurons projecting into the SN whose endings could not be identified. They also found an obligate epidermal clone and frequently observed a PNS clone. We generated 5 abdominal NB 4-3 clones, scoring 1 at stage 15, 2 at stage 16, and 2 at stage 17. We believe the cells previously identified as motoneurons (Schmidt et al., 1997) are actually neurosecretory cells of the TN.

A. Neurosecretory Cells

There are 2-3 neurosecretory cells that project together out of the CNS, appearing to join the TN in the periphery. These cells are slightly smaller than most motoneurons (5.3 mm; n=4) and correlate well with the positions and projections of the Bursicon-containing B1, B2 and B3 neurosecretory cells in Manduca (Taghert and Truman 1982a,b; Carr and Taghert, 1988a,b; Broadie et al., 1990; Tublitz and Sylwester, 1990).

B. Interneurons

There are an additional 10-12 small (3.1 mm; n=6) axonless interneurons at stage 17.



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