496 



THE EEPEODUCTIVE SYSTEM 



much thinner, and a characteristic mucosa. The tunica propria of the 

 mucous membrane is a thin layer of delicate cellular connective tissue 



which loosely attaches the lining epithelium 

 to the muscular coat. The surface of the 

 mucosa presents numerous folds which not 

 only form longitudinal rugae but also pos- 

 sess an intricate network of secondary ridges 

 which are both longitudinal and transverse 

 in direction. This peculiar arrangement re- 

 sults in the appearance of diverticula of 

 various forms and sizes which, except that 

 their epithelium does not differ from that 

 of the surface, might often be interpreted, 

 when seen in section, as representing sec- 

 ondary secreting glands within the mucosa. 

 Slender processes of the corium extend into 

 all the folds of the mucous membrane. 



The lining epithelium of the seminal 

 vesicles is of the columnar type and usually 

 contains but a single layer of cells. Occa- 

 sionally basal cells are also found in the 

 deeper part of the epithelial layer; in such 

 case the epithelium may be said to be of the 

 pseudo-stratified type. This variation may 

 possibly be partly dependent upon the dis- 

 tention or relaxation of the vesicles. The 

 cells of the epithelium contain peculiar 

 granules of yellowish pigment which are 

 present in considerable numbers and are 

 quite characteristic of the organ. The su- 

 perficial cells appear to be readily desquam- 

 ated, and together with coarse granules of 

 secretion form the chief contents of the 

 lumen. Occasional small concretions of ir- 

 regular form, and homogeneous or lamellar 

 structure, similar to those of the prostate 

 gland, are also found. The seminal vesicles 

 usually contain but few spermatozoa. Occasionally these are present in 

 large numbers; at other times they may be entirely absent. Their chief 

 function is now thought to be secretory. 



FIG. 440. MODEL OF A 

 RECONSTRUCTED PROS- 

 TATE GLAND OF MAN. 



The figure includes one 

 lobule. The narrow duct 

 expands and terminates in 

 a large number of alveoli of 

 very varied size and form. 

 X 40. (After Maziarski.) 



