Egger M D, Harris S, Peng B, Schneiderman A M, Wyman R J
Department of Anatomy, UMDNJ-Robert Wood Johnson Medical School, Piscataway 08854-5635.
Anat Rec. 1990 Mar;226(3):373-82. doi: 10.1002/ar.1092260315.
The tergotrochanteral (TTM) "jump" muscles in the second (T2) and third (T3) thoracic segments of the fruit fly, Drosophila melanogaster, were analyzed morphologically and morphometrically in wildtype (Canton-S) and bithorax mutants (abx bx3 pbx/Df(3R)P2). In the transformed T3 segments of mutant flies, the TTMs were greatly increased in fiber number (330% of wildtype), length (141%), and volume (460%), thus manifesting both hyperplasia and hypertrophy. In contrast, TTMs in the "untransformed" T2 segments of mutant flies were both hypoplastic and hypotrophic, in that significant decreases in fiber number (93% of wildtype), length (90%), and volume (80%) were observed. Two relationships emerged from analysis of the morphometric data: 1) Although the fiber numbers and volumes of the transformed T3 TTMs in bithorax flies were greatly increased, the total combined volumes of the TTMs in T2 + T3 remained approximately the same in bithorax compared to wildtype flies. 2) The changes in TTM volumes in bithorax flies compared to those in wildtype were proportional to the relative changes in fiber numbers times the relative changes in muscle lengths. These observations suggest that the genes of the bithorax complex influence the number and the length of tubular muscles fibers of the TTMs, but do not significantly affect the mean cross-sectional areas of these fibers. Fibrillar muscle fibers, which are not found at all in T3 segments in wildtype flies, were observed in the transformed T3 segments of bithorax mutants in 11 of 18 cases (61%), but typically as wisps, not in complete muscles. We suggest that, in the T3 segment of the bithorax flies, the relative differences between the massive transformation of tubular TTMs vs. the minimal appearance of fibrillar muscles may be related, in part, to the relative availability of muscle precursors.
对野生型（坎顿 - S）和双胸突变体（abx bx3 pbx/Df(3R)P2）果蝇黑腹果蝇第二胸节（T2）和第三胸节（T3）中的背转子肌（TTM）“跳跃”肌肉进行了形态学和形态计量学分析。在突变果蝇转化的T3节段中，TTM的纤维数量（野生型的330%）、长度（141%）和体积（460%）大幅增加，表现出增生和肥大。相比之下，突变果蝇“未转化”的T2节段中的TTM既发育不全又萎缩，因为观察到纤维数量（野生型的93%）、长度（90%）和体积（80%）显著减少。对形态计量数据的分析得出了两个关系：1）尽管双胸果蝇中转化的T3 TTM的纤维数量和体积大幅增加，但与野生型果蝇相比，T2 + T3中TTM的总组合体积在双胸果蝇中大致保持不变。2）双胸果蝇中TTM体积相对于野生型的变化与纤维数量的相对变化乘以肌肉长度的相对变化成正比。这些观察结果表明，双胸复合体的基因影响TTM的管状肌纤维数量和长度，但对这些纤维的平均横截面积没有显著影响。在18例中有11例（61%）的双胸突变体转化的T3节段中观察到了纤维状肌纤维，而野生型果蝇的T3节段中根本没有，但通常是细条，而非完整的肌肉。我们认为，在双胸果蝇的T3节段中，管状TTM的大量转化与纤维状肌肉的极少出现之间的相对差异可能部分与肌肉前体的相对可用性有关。
