756 HANDBOOK OF PHYSIOLOGY. 



the second part of the urethra. They are small round bodies, of the 

 size of a pea, yellow in color, resembling the sublingual gland; in 

 structure they are compound tubular mucous glands. 



The Prostate Gland. The prostate is situated (fig. 451) at the 

 neck of the urinary bladder, and incloses the commencement of the 

 urethra. It is somewhat chestnut-shaped. It measures an inch and a 

 half in breadth, and an inch and a quarter long, and half an inch in 

 thickness. 



Structure. The prostate is made up of small compound tubular 

 glands imbedded in an abundance of muscular fibres and connective tissue. 



The glandular substance, which is nearly absent from the front part 

 of the organ, consists of numerous small saccules, opening into elongated 

 ducts, which unite into a smaller number of excretory ducts. The acini 



Rig. 453. Section of a small portion of the prostate, a, gland duct cut across obliquely; b, 

 gland structure; c, prostatic calculus. (Cadiat.) 



of the upper part of the prostate are small and hemispherical; while 

 in the middle and lower parts the tubes are longer and more convoluted. 

 The acini are of two kinds, namely, those (a) lined with a single layer of 

 thin and long columnar cells, each with an oval nucleus in outer part of 

 wall; and those (b) acini resembling the foregoing, but with a second 

 layer of small cortical, polyhedral, or fusiform cells between the mem- 

 brana propria and the columnar cells. The ducts, twelve to twenty in 

 number, open into the urethra. They are lined by a layer of columnar 

 cells, beneath which is a layer of small polyhedral cells. 



The tunica adventitia consists of dense fibrous tissue of two layers, 

 between which is situated a plexus of veins. Large vessels pass into the 

 interior of the organ, to form a broad, meshed, capillary system. Nerves 

 with numerous large ganglion-cells surround the cortex. Pacinian 

 bodies are sometimes found in the substance of the organ. 



