Boyle M, DiNardo S
Rockefeller University, NYC, NY 10021-6399, USA.
Development. 1995 Jun;121(6):1815-25. doi: 10.1242/dev.121.6.1815.
The adult ovaries and testes contain several specialized somatic cell types that support the differentiation of germ cells into mature gametes. Each of these cell types arise from mesodermal cells that constitute the embryonic gonad. To explore the mechanisms governing the development and differentiation of these cells, we focus on the formation of the gonad during Drosophila development. Using markers for the precursors of the somatic cells of the gonad, we identify discrete steps in the development of the gonad. Our results suggest the existence of different populations of gonadal precursors at early stages in gonadogenesis that represent precursors of cell types found within the adult gonad. The functions of the homeotic genes abdominal A and Abdominal B are required for the development of gonadal precursors, however, here we provide evidence that each plays a distinct role. abd A activity alone specifies anterior gonadal precursor fates, whereas abd A and Abd B act together to specify a posterior subpopulation of gonadal precursors. Once specified, gonadal precursors born within posterior parasegments must move to the site of gonad formation. Here, we show that the proper regional identities, as established by homeotic gene function, are required for the arrest of migration at the correct position. Finally, our analysis of late stages of gonadogenesis suggests that abd A is required in a population of cells within parasegments 10 and 11 that partially ensheath the coalescing gonad. Mutations in iab-4 abolish expression of abd A within these cells, and as a result block the coalescence of the gonad.
成年卵巢和睾丸包含几种特殊的体细胞类型，这些体细胞支持生殖细胞分化为成熟配子。这些细胞类型中的每一种都起源于构成胚胎性腺的中胚层细胞。为了探究调控这些细胞发育和分化的机制，我们聚焦于果蝇发育过程中性腺的形成。利用性腺体细胞前体的标记物，我们确定了性腺发育中的离散步骤。我们的结果表明，在性腺发生的早期阶段存在不同群体的性腺前体，它们代表成年性腺中发现的细胞类型的前体。同源异型基因腹部A和腹部B的功能是性腺前体发育所必需的，然而，我们在此提供证据表明它们各自发挥着独特的作用。单独的abd A活性决定性腺前体的前部命运，而abd A和Abd B共同作用决定性腺前体的后部亚群。一旦确定，在后段出生的性腺前体必须迁移到性腺形成的部位。在此，我们表明，由同源异型基因功能建立的适当区域身份对于在正确位置停止迁移是必需的。最后，我们对性腺发生后期的分析表明，在第10和11段中部分包裹合并性腺的一群细胞中需要abd A。iab - 4中的突变消除了这些细胞中abd A的表达，结果阻断了性腺的合并。
