506 THE EEPKODUCTIVE SYSTEM 



The tunica albuginea and trabeculae of the corpus spongiosum arc 

 formed by less dense connective tissue than is found in the corpora 

 cavernosa penis,, and their venous spaces are not so broad. The broad 

 anterior end of the corpus spongiosum forms almost the entire body 

 of the glans penis, being only indented beneath the corona by the conical 

 anterior ends of the corpora cavernosa penis which in this part are 

 blended together to form a single median mass. The urethral canal 

 occupies the axis of the corpus spongiosum from its bulb forward to 

 the urinary meatus at the tip of the glans penis. This canal has already 

 been described in the preceding chapter. It should be recalled that its 

 lining epithelium differs in the several segments, being transitional in 

 its prostatic and membranous portions, and stratified columnar through- 

 out the greater length of the spongy portio'n, changing to stratified 

 squamous in the dilated fossa navicularis of the glans penis. 



The skin of the glans penis is peculiar in the relatively moist char- 

 acter of its epidermis and the consequent imperfect development of its 

 superficial horny layer. Its dermal papillae are conspicuously developed. 

 In the region of the corona the derma contains a ring of large sebaceous 

 glands, the preputial glands, which open on the free epithelial surface. 

 Their secretion forms the smegma, a peculiarly odoriferous sebum. The 

 so-called glands of Tyson are shallow, non-glandular epithelial pockets 

 opening near the frenulum preputii (Lewis). 



The medullated sensory nerves (dorsal nerves of the penis; branches 

 of the pudic) are abundantly supplied with special nerve end-organs. 

 In the skin they form free varicose endings among the epithelial cells, 

 and are connected with tactile corpuscles of Meissner in the dermal 

 papillae. Deeper in the skin are many end bulbs of Krause, while still 

 deeper are the peculiar genital corpuscles. Naked fibrils pass to the 

 mucosa of the urethra. Pacinian corpuscles are also found in the loose 

 connective tissue and in the tunica albuginea of the corpora cavernosa. 

 Sympathetic nerve fibers are abundantly supplied to the walls of the 

 blood-vessels and to the smooth muscle of the erectile tissue. Branches 

 from the third and fourth sacral nerves also enter the penis as the 

 nervi erigentes, supposed to convey the impulse to erection as vasodilator 

 fibers. 



The lymphatics of the penis form an abundant superficial set in the 

 subcutaneous tissue; these follow the larger blood-vessels and empty 

 into the inguinal lymph glands. A less abundant deep set of lymphatics 

 in the erectile tissue, also, accompanies the blood-vessels of these parts, 

 but is distributed to the pelvic lymph glands. 



