Paired Circumesophageal Connectives Fail to Form in Single-minded Mutants

Figure 7
Paired circumesophageal connectives fail to form in single-minded mutants.

(A-C) Lateral optical sections in plane in which circumesophageal connectives would normally develop (laser confocal microscopy). (D-I) Frontal optical sections in plane in which both circumesophageal connectives would normally develop (laser confocal microscopy). (J) Midsaggital section. (K) Frontal section. (L) Lateral views through brain and subesophageal ganglion of P[sim/lacZ] transformed wildtype (laser confocal microscopy). Neuron-specific anti_hrp immunoractivity (A, D, G), glial cell-specific immunoreactivity (B,E,H), combined anti-Hrp (red) and repo immunoreactivity (green/yellow) (C,F,I), axon-specific BP102 immunoreactivity (J,K), combined anti-HRP immunoreactivity (red) and anti-ß-galactosidase immunoreactivity (green/yellow) (L).

(A-C) Longitudinal axon pathways across a gap (A-C, arrows) between the brain hemispheres and the subesophageal ganglion do not form and the longitudinal glial cells do not bridge the gap.
(D-F) Commissural fascicles, preoral brain tracts and associated glial structures are established between the brain hemispheres but paired circumesophageal connectives (D, asterisks) do not form (compare with Fig.2G-I).
(G-I) Ectopic midline-descending pathways (G, arrow) seen in 1/5/ of the mutants. Longitudinal axons fuse medially and project aberrantly from the brain to the ventral ganglia (compare with Fig.2G-I).
(J) Aberrant ectopic midline pathway (arrows) projecting along the foregut-associated structures.
(K) Preoral commissure (filled arrow) and peoral brain tracts (arrowheads) are present despite the absence of paired circumesophageal connectives (asterisks).
(L) P[sim/lacZ] enhancer detector staining indicating that single-minded is expressed in the lower part of the brain (arrow) located just anterior and dorsal to the subesophageal ganglion. Some of the stained cells in this region are also labeled by the glial-specific anti-repo antibody and may, thus, be longitudinal glial cells.
Stages 12/3 (A,B,C), 14 (L), 16 (D-K). Scale bar10.

Flybrain    Development    Embryonic Brain Development    Formation of Commissural and Descending Pathways    Paired Circumesophageal Connectives Fail to Form

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