Early development of the human mesonephros

Abstract

The mesonephrogenic cord disintegrates into approximately 35-40 provesicular cell masses which are in close contact with the mesonephric (Wolffian) duct (WD) on their lateral side. Here, the epithelium of the WD is columnar and shares a common basal lamina with the provesicular cell masses. This in turn gives rise to a sickle-shaped pseudostratified epithelium. The concavity of the sickle is filled by spherical cells, the transition of which into the surrounding connective tissue is continuous. The sickle is transformed into a distillation flask and becomes separated from the mesonephric duct while the spherical cells maintain a connection to it by a-for the time being-solid outlet pipe. The columnar epithelium of the mesonephric duct becomes a multilayered cone, whose surface is in contact with the outlet tube. Shortly after, a continuous lumen is formed in the cone and the outlet pipe which is delimited by cells becoming columnar and forming a basal lamina. The epithelial anlage of the nephron is clearly separated from the surrounding mesenchyma by these processes. The flask eventually becomes a corpusculum, the outlet pipe a secretory (proximal) as well as collecting tubule, and the cone of the mesonephric duct a mesoureter. The various sections display differentially differentiated epithelia that are clearly distinct from each other. The mesoureter behaves differently during differentiation of epi-and paragenitale: in the epigenitale, it is short and runs into the collecting tubules of the nephrons at the lateral side of the convolved tubules, whereas a long mesoureter crosses the dorsal side of the convolved tubules and joins the corresponding collecting tubules at the far end of the mesonephros in the paragenitale.

Similar developmental patterns in immunolocalisation of stem cell factor and KIT in bovine meso- and metanephros

“…The epithelium of the outside wall showed similarities to the epithelium of the proximal tubule. The epithelium of the collecting duct system continued in the WolYan duct and was characterised by a bright subnuclear area (Ludwig and Landmann 2005). At 1.7 cm CRL, KIT was widely expressed along the entire epithelium lining the glomerular capsules and tubules (Fig.…”

“…Although further characterisation of the bovine cells is needed, the close vicinity of some of the bovine cells to capillary-like structures may indicate an involvement of KIT-positive stromal cells in the development of the kidney vasculature. The fact that the receptor and its ligand show similar distribution patterns in mesoand metanephric epithelia indicates the existence of similar developmental processes in the two foetal kidneys (Ludwig and Landmann 2005;Magro et al 2001;Sainio and Raatikainen-Ahokas 1999).…”

“…This duct interacts reciprocally with the mesenchyme of the intermediate mesoderm to form the two renal organs. In the case of the more cranial and earlier forming mesonephros, the WolYan duct epithelium proliferates in distinct sections, bulges out, becomes Wrst bi-and then multilayered, and Wnally forms the collecting ducts, which become connected to the distal parts of the nephrons (Ludwig and Landmann 2005). In the case of the more caudal and later-forming metanephros, a primary bud, known as the ureteric bud for the metanephros, sprouts out from the caudal end of the WolYan duct, invades the intermediate mesoderm, and then branches out to form a tree-like collecting duct system (O'Rahilly and Muecke 1972).…”

“…the loop of Henle is missing. However, the similarities in the structural formation of the two renal organs suggest that the reciprocal epithelial and mesenchymal cell-cell interactions which take place in both organs are under the control of similar factors and their receptors (Ludwig and Landmann 2005;Magro et al 2001;Vize et al 1997).…”

Sturge-Weber Syndrome and Haematuria: a Case Report of an Unusual Presentation

“…In utero, the renal system is derived from the intermediate mesoderm, and it is supplied by the right and left renal arteries, which branch into small segmental arteries, and then lobar branches subsequently-the latter gives off interlobular arteries supplying the individual glomeruli [20,21]. Infarction of the renal system is rare and most commonly is caused by thromboembolic events, which occlude the segmental arteries, thus giving the classical appearance of a wedge-shaped area of hypoperfusion on CT imaging [22].…”