Figure 10.

Schematic representations of stages during formation of the metanephridial system in Lepidochitona corrugata.A. Initial anlage appearing. B. Kidney components become separated from the common anlage, first differentiations of the heart appear in remaining anlage. C. Further differentiation of kidney components and heart. D. Basic filtration organization completed, kidneys become enlarged, heart formation finished. E. Additional substantial growth of the kidneys. ahp, anlage of heart and pericardium; ark, anlage of renopericardial duct and kidney; ed, efferent nephroduct; h, heart; ia, initial anlage of the metanephridial and circulatory system; k, kidney; pe, pericardium; rp, renopericardial duct.