Older texts describe the pronephros as forming through the fusion of multiple nephrotomes.
Modern visualization methods, such as scanning electron microscopy, in situ hybridization, and confocal microscopy, combined with the simple approach of peeling off the epidermis to see the forming kidney, have shown that this is not the case.
[citation needed] Nephric mesenchyme separates from the intermediate mesoderm as a single elongated primordia.
These rounded bumps are the structures observed in histological sections that are referred to as nephrotomes.
[citation needed] Nephrotomes are not related to nephrostomes, which are thin ciliated funnels that link pronephric nephrons to the coelom.