Evan A P, Gattone V H, Blomgren P M
Scan Electron Microsc. 1984(Pt 1):455-73.
The present study uses scanning electron microscopy to review mammalian kidney development using the dog model. Canine mesonephros and metanephros are examined, focusing on the structure of the nephron from each and the maturation of the different cell types found in the metanephric nephron. The mesonephros possesses numerous nephrons each with a glomerulus, proximal, distal, and collecting tubule which empty into the mesonephric (Wolffian) duct. The mesonephros does not have cortical and medullary regions. The metanephric nephron not only possesses a glomerulus and the same tubular segments as described for the mesonephric nephron (proximal, distal, and collecting tubules), but also has tubular segments that are found in the medulla, namely the loop of Henle and thick ascending limb. Mammalian metanephric glomerulogenesis and tubulogenesis follows an orderly centrifugal pattern (from inner to outer cortex). The glomerular visceral epithelium initially has a columnar shape which is modified into a cuboidal sheet possessing numerous slender foot processes. The endothelium begins as a double layer with minimal fenestrae. With maturation, a single cell layer is formed possessing many large fenestrae. The maturation of the proximal tubule is documented by changes in the apical microvilli, and the foldings of the lateral and basal cell surfaces. Initially, the collecting tubule is lined by a primordial cell which differentiates into both the principal and intercalated cells.
本研究使用扫描电子显微镜，以犬类为模型来观察哺乳动物肾脏的发育过程。研究对犬类的中肾和后肾进行了检查，重点关注每个肾单位的结构以及后肾肾单位中不同细胞类型的成熟情况。中肾包含许多肾单位，每个肾单位都有一个肾小球、近端小管、远端小管和集合小管，这些小管会汇入中肾（沃尔夫管）。中肾没有皮质和髓质区域。后肾肾单位不仅拥有一个肾小球以及与中肾肾单位相同的肾小管节段（近端小管、远端小管和集合小管），还具有在髓质中发现的肾小管节段，即亨氏袢和髓袢升支粗段。哺乳动物后肾的肾小球发生和肾小管发生遵循一种有序的离心模式（从内皮质到外皮质）。肾小球脏层上皮最初呈柱状，随后转变为具有许多细长足突的立方状薄片。内皮最初是具有极少窗孔的双层结构。随着成熟，形成了具有许多大窗孔的单层细胞。近端小管的成熟通过顶端微绒毛以及侧面和基底细胞表面的褶皱变化得以体现。最初，集合小管由原始细胞内衬，该原始细胞会分化为主细胞和闰细胞。
