358 THE ORGANS 



mucous, submucous, and muscular. The structure of the wall dilters 

 in the different parts of the urethra. 



The mucous membrane (Fig. 250) consists of ejnthelium and 

 stroma. The epithelium of the prostatic part is stratified squamous 

 (transitional), resembling that of the bladder. In the membranous 

 part it is stratified columnar or pseudostratified. In the penile 

 portion it is pseudostratified up to the fossa navicularis, where it 

 changes to stratified squamous. The epithelium rests upon a base- 

 ment membrane, beneath which is a thin stroma rich in elastic fibres 

 and "having papillae which are especially prominent in the terminal 

 dilated portion of the urethra, the fossa navicularis. The stroma 

 merges without distinct demarcation into the submucosa. 



The submucosa consists of connective tissue and, in the penile 

 portion, of more or less longitudinally disposed smooth muscle. It 

 contains a dense network of veins — cavernous veins — which give it 

 the character of erectile tissue (Fig. 250). 



The muscular coat is thickest in the prostatic and membranous 

 portions. Here it consists of a thin inner longitudinal and a thicker 

 outer circular layer. A definite muscular wall ceases at the beginning 

 of the penile portion, although circularly disposed smooth muscle cells 

 are found in the outer part of the submucosa of the penile urethra. 



Throughout the mucosa of the entire urethra, but most numerous 

 in the penile portion, are simple branched tubular mucous glands, 

 the glands of Littre. They are lined with columnar epithelium and 

 the longer extend into the submucosa. 



TECHNIC 



(i) For the study of the general topography of the penis, remove the skin 

 from the organ and cut into transverse slices about 0.5 cm. in thickness. Fix in 

 formalin-Miiller's fluid (technic 6, p. 7), cut rather thick sections across the 

 entire penis, stain with hasmatoxylin-picro-acid-fuchsin (technic 3, p. 21) or with 

 hjematoxylin-eosin (technic i, p. 20) and mount in balsam. 



(2) For the study of the structure of the penile portion of the urethra and of 

 the erectile tissue of the corpus spongiosum, cut away the corpora cavernosa, 

 leaving only the corpus spongiosum and contained urethra, and treat as above. 

 Sections should be thin and stained with hajmatoxylin-eosin. 



(3) The same technic is to be used for the membranous and prostatic 

 portions of the urethra. 



II. FEMALE ORGANS 



The Ovary 



The ovary is classed as one of the ductless glands. Its specific 

 secretion is the ovum. The ovary has no duct system which is 



