Changes in the protein spectrum of the chick embryo mesonephros and metanephros in the course of development.

The protein spectra of two fractions (the soluble and the membrane fraction) of chick embryo kidney homogenates were isolated by electrophoresis on polyacrylamide gels with the aim of detecting the kidney differentiation process at the molecular level and, at the same time, of evaluating similarities in the construction of the mesonephros and metanephros at this level. Corresponding stages of the above two types of kidney were chosen for studying changes in protein structure during differentiation--i.e.

[Succinate dehydrogenase activity in the mesonephros in the process of development of chick embryos].

The activity of succinate dehydrogenase in the mesonephros tissue of chick embryos is rather high on the 6th day of embryonal development and is not subjected to significant changes up to the 17th day. The absence of wide variations in the activity of this enzyme during the period of degeneration of the mesonephros may be due to a parallel decrease in the organ's mass and in the number of its mitochondria.

Formation of the chick mesonephros. 4. Course and architecture of the developing nephrons.

Using colour microinjections the course of mesonephric nephrons was visualized in embryos of White Leghorn chicks on days 5-18. From the stage of the S-shaped body until their full maturity, the nephrons generally retain the S-shaped form, with two main flexures. The first flexure is formed at the point where the tubule runs closest to the Wolffian duct, the second, more distal flexure, at the site of juxtaposition to Bowman's capsule.