Penis

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The penis is a copulatory organ of the external genitalia of the males. It consists of three parts; root (radix), body (shaft) and glans. 

From the perspective of histology, the most remarkable feature of the penis is its core of erectile tissue. The penis is composed of three cylindrical columns of erectile tissue, namely the two corpora cavernosa and the corpus spongiosum, which are bound together by a dense fibroelastic layer called the tunica albuginea. The corpora contain irregular vascular spaces, lined by endothelium. These fill with blood during erection, while the corpus spongiosum protects the urethra from compression by the engorged corpora cavernosa.

The tunica albuginea is surrounded by a layer of superficial fascia that contains connective tissue, prominent blood vessels, and nerves. Surrounding the superficial fascia is the outermost sheath of penile skin which is covered with stratified squamous keratinized epithelium. Unless circumcised, it extends over the glans as the prepuce or foreskin, which acts as a retractable protective fold of skin. 

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