Molchanova V V
Arkh Anat Gistol Embriol. 1975 May;68(5):99-106.
The kidneys of tadpoles of different developmental stages were examined in preparations processed histologically and histochemically. It was found that differentiation of the provisory excretory organ tubules in frogs was "shortened" or "accelerated" after P. P. Ivanov's terminology, and developed differently as compared with differentiation of tubules of the definitive organ of excretion -- the primary kidney. When differentiating the epithelium of the proximal portion of the primary kidney nephron passes the stage of the high prismatic false-stratified epithelium. The pronephros tubules do not pass this stage and the epithelium becomes a strict monolayer from the very beginning. No mitoses are observed in the pronephros tubule epithelium even at the earliest differentiation stages. Later on, the beginning of tubule functioning, and with the reduction, and later disappearance of yolk granules in the epithelium solitary mitoses make their appearance. The mitotic activity of the primary kidney tubule epithelium is very high (70%) at the early stage of differentiation. Then its mitotic activity decreases (30%), and after the beginning of the tubule functioning mitoses in its epithelium become solitary.
对不同发育阶段蝌蚪的肾脏进行了组织学和组织化学处理的标本检查。结果发现，按照P. P. 伊万诺夫的术语，青蛙临时排泄器官小管的分化被“缩短”或“加速”，并且与最终排泄器官——初级肾脏的小管分化相比，发育方式有所不同。在初级肾脏肾单位近端部分的上皮细胞分化时，会经过高柱状假复层上皮阶段。前肾小管不经过这个阶段，上皮细胞从一开始就成为严格的单层。即使在最早的分化阶段，前肾小管上皮细胞中也未观察到有丝分裂。后来，随着小管功能的开始，以及上皮细胞中卵黄颗粒的减少和随后消失，单个有丝分裂开始出现。在分化早期，初级肾脏小管上皮细胞的有丝分裂活性非常高（70%）。然后其有丝分裂活性降低（30%），并且在小管功能开始后，其上皮细胞中的有丝分裂变得单个出现。
