Fig. 2. Defects in the adult GF and TTMn are induced by blocking endocytosis at various stages in development. (A) Anatomy of the GF system after various temperature shifts when UAS-shi^ts was driven by the A307 Gal4 enhancer. (A1) A temperature shift at 16% of pupal development followed by regeneration and examination in the adult stage. Two specimens are represented. In one a GF is trapped in the brain, in the thorax of another both GFs exhibit the `overgrowth' phenotype. (A2) A temperature shift at 33% of pupal development produced a bendless-like phenotype where the large lateral bend is missing from both GFs in the adult. (A3) A temperature shift at 75% of development had no detectable effect on the structure of the GF. (A4) Both late temperature shifts and controls exhibit normal bends. This particular specimen was never temperature shifted and illustrates the structure of the GF in the adult stage. Scale bar: 20 µm. (B) Physiology of the GF system. Each pair of traces is taken from a specimen temperature shifted at the time indicated. (B1) Early temperature shifts disrupted the TTM muscle and no recordings could be obtained. The DLM was often excited by the GF but latencies were long and very few stimuli in a train elicit a response. (B2) Temperature shifts during synapse formation increased the latencies and decreased following frequency. (B3) Response latencies were increased and, following frequency, decreased when temperature shifts occurred between 62.5-75% of pupal development. (B4) Temperature shifted at 84% had no statistically significant effect on the physiology and this specimen illustrates the normal physiology (see Table 1 for quantification). In control specimens, the latency for TTM is about 0.9 mseconds and for DLM was 1.4 mseconds; both motoneurons could follow the 100 Hz stimulus without fail. The upper trace in each panel is taken from the TTM, the lower trace from the DLM. In each set of traces, the individual stimulus illustrates the latency and wave form of the response, the sweep with 10 stimuli illustrates the response to repetitive stimuli.