Comparative analysis of mesonephric transcriptomics: Conservation of the developmental lineage of nephron stages.

The mammalian kidney develops in three sequential stages referred to as the pronephros, mesonephros, and metanephros, each developing from the preceding form. All three phases of kidney development utilize epithelized tubules called nephrons, which function to take in filtrate from the blood or coelom and selectively reabsorb solutes the organism needs, leaving waste products to be excreted as urine. The pronephros are heavily studied in aquatic organisms such as zebrafish and Xenopus, as they develop quickly and are functional. The metanephros is a preferred mammalian kidney model, as it best recapitulates human disease. However, very little is known about the mesonephric stage of kidney development in any organism. The pronephros extend to form the mesonephric duct, which ultimately develops into the Wolffian duct in male amniotes. Meanwhile, in organisms that lay their eggs in aquatic environments, the mesonephric kidney is the final form that is generated. Therefore, further understanding of the development and physiology of these kidneys will provide insight into the urogenital system as well as its evolutionary conservation. To gain a better understanding of its structure and cell types, we analyzed the developing mesonephros by in situ and single-cell mRNA sequencing of cells the that make up the developing mesonephros. By comparing these data to those published for the pronephros and mammalian metanephros, we were able to evaluate nephron conservation between the three kidney stages.