UROGENITAL SYSTEM OF MYXINOIDS 



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ever, where the duct is larger, the trunk of the tubules is only 

 from one-fourth to one-thii'd as large as the duct. At the 

 opening of the trunk of the tubule into the duct, the epithelial 

 cells of both are continuous with each other, including their 

 basal membranes (fig. 61). When the trunk of the tubule lies 

 close beside the duct, each has its own envelope of connective 

 tissue, but the two are bound together by a compact band of 

 connective tissue arranged in concentric layers. The trunk of 

 the compound tubules varies somewhat in length, but is not 

 more than a fraction of a millimeter, approximating 0.75 mm. 

 The trunk and neck together are about 1.5 mm. long. In some 

 cases the neck may be longer than the trunk, but it is usually 

 much shorter. 



Waste granules resembling those in the duct are present in 

 large quantity in the lumen of both the plain and compound 

 tubules along their entire length. The short columnar cells of 

 the plain tubules and of the necks of the convoluted tubules 

 lack the yellowish bodies which are found in the cells of the duct, 

 but the long columnar cells of the trunk of the compound tubules 

 have more or less of them. 



Each glomerulus almost entirely fills its Bo\vman's capsule. 

 The squamous epithelial lining of the capsule continues around 

 the glomerular mass. The capsule is usually oval in shape. 

 The glomeruli are usually largest at the anterior end of the 

 duct, and diminish in size gradually toward the posterior, the 

 most posterior being the smallest. For instance, the following 

 are measurements of glomeruli from different regions of the 

 duct: 



