9 The male genitalia
Unlike the female genitalia, the male organs are readily accessible for examination. As for women, taking a sexual case history and examining a male is embarrassing and intrusive, so care must be taken to ensure confidentiality, privacy and comfort. An overview of structure and function will help you gain confidence when taking a history and examining the genitalia and will aid the interpretation of symptoms and signs.
Structure and function
The male genitalia include the penis, scrotum, testes, epididymides, seminal vesicles and prostate gland (Fig. 9.1). The penis provides a common pathway to the exterior for both urine and semen. In fetal development, the testes develop close to the kidneys and slowly migrate caudally, emerging at the external inguinal ring in the eighth month of development and descending into the scrotum in the ninth month. The neural, vascular and lymphatic supply to the testes also arise from near the kidney and the migrating testes drag these structures through the inguinal canal into the scrotum. This has important clinical implications, as renal pain is often referred to the scrotum and the natural route for lymphatic spread of testicular cancer is to para-aortic (rather than inguinal) nodes.
PUBERTY
Hormonal changes in puberty
Throughout male puberty, LH levels increase slowly and steadily (Fig. 9.2), whereas FSH levels increase more sharply in early puberty, with a more gentle increase afterwards. FSH stimulates the Sertoli cells and regulates the growth of seminiferous tubules and spermatogenesis. As most of the testis is formed of tubules, the increased testicular volume in puberty is largely under the control of FSH. LH stimulates the Leydig (interstitial) cells which synthesise testosterone from cholesterol (Fig. 9.3). Testosterone circulates bound to sex hormone-binding globulin (SHBG). The linear growth spurt follows closely behind the surge of testosterone. Some testosterone is converted to oestradiol in the Leydig cells and other extragonadal tissue sites. The effects of testosterone are shown in Table 9.1. The importance of oestrogen in males remains unclear, although it does regulate the synthesis of SHBG.
Table 9.1 Effects of testosterone
Development of secondary sexual characteristics
Tanner described the pubertal development of the male genitalia and pubic hair growth (Fig. 9.4). Initially, the testes enlarge and the scrotal skin becomes thin and red (stage 2). The enlargement of the phallus occurs later in the growth spurt and is associated with thickening, crinkling and pigmentation of the scrotal skin (stage 3). Increasing levels of gonadal and adrenal androgens stimulate the growth of pubic, axillary and facial hair. Pubic hair begins to develop as sparse, long, slightly curly hair at the base of the phallus (stage 4). Later, coarser, curlier hair extends to cover the symphysis pubis and finally extends to the inner thigh and along the linea alba (this constitutes the male escutcheon) (stage 5).
Male fertility
The male testis is composed of a network of tightly coiled and convoluted seminiferous tubules that drain through the rete testis into the epididymis. Spermatozoa develop from the germinal epithelium of the seminiferous tubules which lie in close contact with the Leydig and Sertoli cells (Fig. 9.5). LH binds to the Leydig cells, stimulating the production of testosterone from cholesterol. FSH binds to the Sertoli cells, stimulating the synthesis of inhibin, a peptide hormone that inhibits FSH production by the pituitary (Fig. 9.6). The development from immature spermatogonia to mature spermatozoa takes 72 days. The passage of the sperm through the epididymis to the ejaculatory ducts takes a further 14 days, during which time the spermatozoa become motile.
PENIS
The penis consists of the two sponge-like cylinders, the corpora cavernosa, forming the dorsal and lateral surfaces, and the corpus spongiosum, which ends in a bulbous expansion, the glans penis (Fig. 9.7). The urethra passes through the corpus spongiosum. The skin covering the corpora extends over the glans to form the prepuce.
Tactile and psychogenic stimuli cause sexual arousal. An autonomic (parasympathetic) reflex causes increased arterial flow through branches of the pudendal artery to the penis and fills the corpus spongiosum. The organ assumes the erectile position necessary for vaginal penetration. The reflex is completed by a sympathetic neural outflow that results in contraction of the ejaculatory ducts and the bladder neck, causing ejaculation of semen and orgasm. This is followed by increased tone in the arterioles and sinusoids of the corpora, diversion of blood away from the penis and, finally, detumescence.
SCROTUM AND ITS CONTENTS
The left testis almost always lies lower than the right. Each testis is ovoid in shape, measuring approximately 4 × 3 × 2 cm. A fibrous capsule, the tunica albuginea, invests the testis. The seminiferous tubules converge and anastomose posteriorly to form the efferent tubules which converge to form the head of the epididymis (Fig. 9.8). This, in turn, gives rise to the body and tail which drain into the vas deferens. The vas deferens passes through the inguinal canal (Fig. 9.9), joining the seminal vesicles, which, in turn, converge to form the ejaculatory duct. The epididymis attaches along the posterior border and upper pole of the testis. Both the testis and the epididymis have vestigial remnants of fetal development known as theappendix testis and hydatid of Morgagni, respectively. These occasionally twist and can cause severe testicular pain.
PROSTATE
The structure of the prostate is described in Chapter 7. The organ envelops the first part of the urethra and the ejaculatory ducts from the seminal vesicles, which open into the prostatic urethra. The prostate secretes a specialised fluid that provides lubrication before intercourse and serves also to increase the volume of the ejaculate.
Symptoms of genital tract disease
At the outset of your history-taking, you will already have ascertained whether the patient is single or married and if he has fathered any children. The genital and sexual history follows on naturally from the urinary tract history (see Ch. 7). Ask about penile discharge, pain or swelling of the testes and ability to enjoy normal sexual relations. These questions should provide the cue for a shy or inhibited patient to talk about sexual or genital problems. Depending on the nature of the presenting symptoms, you may wish to ask about homosexual contact. You may feel uneasy about phrasing the question but in societies in which AIDS is acknowledged as a problem, the majority of patients understand the importance of the question and most often will not take offence to a question like ‘Have you ever had a homosexual partner?’ or ‘Do you practise safe sex?’ If a genital or sexual symptom becomes apparent, assure the patient of the confidentiality of the interview and attempt to analyse the problem in greater depth.
URETHRAL DISCHARGE
A urethral discharge is a common presenting symptom. Remember that a discharge of smegma from a normal prepuce is very different from a discharge caused by urethritis. In urethritis, the patient may notice staining of his underwear and complain of urinary symptoms such as burning or stinging when passing urine. Sexually transmitted disease is a common cause of urethral discharge and patients concerned about sexually transmitted disease will usually mention fear of it. If this information is not forthcoming, ask the patient directlyabout the possibility of contact with sexually transmitted disease. Ask about a recent episode of gastroenteritis, for urethritis may follow a few weeks later. Reiter’s syndrome (Fig. 9.10) is the most florid manifestation of this association and is characterised by a urethral discharge, balanitis, painful joints (arthritis and tendinitis) and bilateral conjunctivitis.
Questions to ask
Differential diagnosis
