Numerous investigations are dealing with anlage of the mammalian kidney and primary development of nephrons. However, only few information is available about the last steps in kidney development leading at birth to a downregulation of morphogen activity in the nephrogenic zone and to a loss of stem cell niches aligned beyond the organ capsule. Surprisingly, these natural changes in the developmental program display similarities to processes occurring in the kidneys of preterm and low-birth-weight babies. Although those babies are born at a time with a principally intact nephrogenic zone and active niches, a high proportion of them suffers on impairment of nephrogenesis resulting in oligonephropathy, formation of atypical glomeruli, and immaturity of parenchyma. The setting points out that up to date not identified noxae in the nephrogenic zone hamper primary steps of parenchyma development. In this situation, a possible therapeutic aim is to prolong nephrogenesis by medications. However, actual data provide information that administration of drugs is problematic due to an unexpectedly complex microanatomy of the nephrogenic zone, in niches so far not considered textured extracellular matrix and peculiar contacts between mesenchymal cell projections and epithelial stem cells via tunneling nanotubes. Thus, it remains to be figured out whether disturbance of morphogen signaling altered synthesis of extracellular matrix, disturbed cell-to-cell contacts, or modified interstitial fluid impair nephrogenic activity. Due to most unanswered questions, search for eligible drugs prolonging nephrogenesis and their reliable administration is a special challenge for the future.

中文翻译：

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治疗性延长早产儿和低出生体重婴儿肾发生的概念必须符合肾发生区的结构功能特性

许多研究涉及哺乳动物肾脏的原基和肾单位的初级发育。然而，关于肾脏发育的最后步骤的信息很少，导致出生时肾发生区的形态发生素活性下调，并导致器官囊外排列的干细胞壁龛丢失。令人惊讶的是，发育程序中的这些自然变化与早产和低出生体重婴儿肾脏中发生的过程相似。尽管这些婴儿出生时具有基本完整的肾源区和活跃的生态位，但其中很大一部分肾发生受损，导致少肾病、非典型肾小球形成和实质不成熟。该设置指出，迄今为止尚未在肾源区发现的 noxae 阻碍了实质发展的主要步骤。在这种情况下，一个可能的治疗目标是通过药物延长肾发生。然而，实际数据提供的信息表明，由于肾源区的显微解剖出人意料地复杂，在迄今为止尚未考虑到有纹理的细胞外基质和间充质细胞突起与上皮干细胞之间通过隧道纳米管进行特殊接触的壁龛中，给药存在问题。因此，仍然需要弄清楚形态发生素信号的紊乱是否会改变细胞外基质的合成、细胞间接触的紊乱或间质液的改变是否会损害肾源性活动。由于大多数未回答的问题，