METANEPHRIC ANLAGE OF CHICK 
415 
constitute the nephrogenous tissue proper. The cells in im¬ 
mediate contact with the ureteric epithelium appear somewhat 
hypertrophied. They have acquired an epithelial arrangement, 
grouping themselves radially around the ureteric epithelium. 
The cells at a distance from the ureteric branches are smaller 
and less densely packed. 
The accounts of the normal development of the metanephros 
usually describe the nephrogenous tissue as being divided into 
two zones-—an inner zone, the anlage of the secretory tubules 
Text figure A Diagrammatic drawing of metanephric analage, isolated from 
a seven-day chick embryo, as it appeared under dissecting microscope. H, 
cranial group of ureteric branches; N.T., nephrogenous tissue; T, caudal group of 
ureteric branches; U, unbranched portion of ureteric channel. 
proper, and an outer zone, the anlage of the connective-tissue 
capsule and stroma of the kidney. The outer zone is described 
as developing in advance of the inner zone and forming a rather 
broad investment around the organ. According to Felix, the 
two zones are particularly well defined in the sea-gull. But both 
Felix and Lillie agree that in the chick it is practically impossible 
to distinguish the two zones. As seen from figure 1, the two 
zones are indistinguishable in the anlage of the seven-day chick 
embryo. The denser tissue around the ureteric branches merges 
