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MANUAL OF HISTOLOGY. 



epithelial cells in their acini, and at their orifices with lami- 

 nated epithelium, are also present. The muscular tissue in 

 this part of the urethra is intimately connected with that of 

 the prostate ; its fasciculi have generally a longitudinal direc- 

 tion, and send off oblique bundles into the mucous mem- 

 brane, (b) The membranous por- 

 tion of the urethra has its mucous 

 membrane covered by an epithe- 

 lium similar to that met with in 

 the prostatic portion. The glands 

 of Littre are absent. Beneath the 

 mucous membrane a long-meshed 

 erectile tissue of a cavernous na- 

 ture is found. Here the organic 

 muscular layer is poorly devel- 

 oped, and it is covered by trans- 

 verse bundles of striped muscular 

 fibres, the musculus uretliralis. (c) 

 Passing to the spongy portion, the 

 mucous membrane is found thrown 

 into longitudinal folds, which are 

 in places connected by transverse 

 ones, forming depressions, known 

 as the lacuncB Morgagnii. These 

 are not glandular in their nature. 

 The epithelium covering the mu- 

 cous membrane in this portion is 

 mostly cylindrical, but as it ap- 

 proaches the meatus urinarius 

 gradually assumes a pavement 

 character. Glands of Littre are found throughout this part. 

 The muscular elements are even less prominent here than in 

 the membranous portion. 



Well-developed and numerous papillae are seen projecting 

 from the mucous membrane of the urethra into the epithelium. 

 They possess a single capillary loop, or several loops are ob- 

 served, especially in the fossa navicularis. These papillae are 

 absent or imperfectly developed at the points where a transitional 

 epithelium is met with. Here the capillaries are arranged to con- 

 stitute a reticulum beneath and parallel to the epithelial covering. 

 The nerves of the urethra are found forming a network 



FIG. 103. Transverse section through 

 the spongy portion of the urethra (corpus 

 cavernosum nrethrae) : &, tunica mucosa ; c, 

 muscular cords; d, vascular spaces of the 

 corp. cavern. ; #, glands ; /, excretory duct 

 of gland ; g, longitudinal muscles ; A, tunica 

 albuginea. Klein. 



