Ooi E C, Youson J H
Am J Anat. 1979 Jan;154(1):57-79. doi: 10.1002/aja.1001540105.
The opisthonephric kidney of larval anadromous sea lamprey, Petromyzon marinus L., undergoes a programmed regression during metamorphosis. Degeneration is initiated in the anterior end of each kidney and progresses posteriorly until the kidneys are reduced to short, pigmented strands by the end of metamorphosis. The first sign of degeneration in both the epithelium of the renal corpuscles and the tubules is a folding of the basal lamina. Autolysis then occurs throughout the entire epithelium of the nephron with the gradual accumulation of larger and greater numbers of acid phosphatase-containing autophagic vacuoles, cytosomes, and myelin figures. Cytoplasmic debris and electron-dense material accumulates in the tubular lumina and in the urinary space. Although no definitive evidence is provided for the method of removal of the tubular epithelium, macrophages play a large part in the phagocytosis of the components of the renal corpuscle. Mesangial cells appear to engulf debris from the capillaries while a second type of macrophage is involved in the destruction of podocytes and parietal epithelial cells. The method of programmed degeneration of the renal corpuscle closely resembles descriptions of the mammalian renal corpuscle in diseased conditions. The sole surviving element of the degeneration of the entire nephron epithelium is a pleated basal lamina. The regressing larval opisthonephros has potential as an alternative system for studying a normal developmental pattern such as tissue regression.
溯河洄游型海七鳃鳗（Petromyzon marinus L.）幼体的后位肾在变态过程中经历程序性退化。退化始于每个肾脏的前端，并向后发展，直到变态结束时肾脏缩小为短的、有色素沉着的条索。肾小体和肾小管上皮细胞退化的第一个迹象是基膜折叠。随后，整个肾单位上皮细胞发生自溶，含有酸性磷酸酶的自噬泡、细胞小体和髓鞘样结构的数量逐渐增多并积累。细胞质碎片和电子致密物质积聚在肾小管腔和尿腔中。虽然没有提供关于肾小管上皮细胞清除方式的确切证据，但巨噬细胞在吞噬肾小体成分中起很大作用。系膜细胞似乎吞噬来自毛细血管的碎片，而另一种类型的巨噬细胞参与足细胞和壁层上皮细胞的破坏。肾小体程序性退化的方式与哺乳动物患病状态下肾小体的描述非常相似。整个肾单位上皮细胞退化后唯一存活的成分是褶皱的基膜。退化的幼体后位肾有潜力作为研究组织退化等正常发育模式的替代系统。
