Classification and main functions
The organs of the male reproductive system are divided into two large groups:
- External: scrotum and penis.
- Internal: prostate gland, testes with their accessory apparatus, vas deferens, seminal vesicles, and bulbourethral glands.
The system performs three global physiological tasks. The main one is reproductive. The endocrine function is carried out by the prostate and testes, which are hormonally regulated organs involved in the metabolism and synthesis of sex hormones. The urinary role is assigned to the penis, through which urine excretion is carried out.
Anatomy of the testis and spermatic cord
The testis (testis, Greek orchis, didymis) is a paired male gonad located in the scrotum. It is an organ of mixed secretion: spermatogenesis (generative function) takes place here, and testosterone is synthesized (endocrine function).
The testis is connected to the pelvic organs through the inguinal canal by means of the spermatic cord (funiculus spermaticus). It is a paired anatomical structure covered by common fascial layers. It comprises a complex of nerves, blood vessels, and the vas deferens.
Structure of the penis and mechanism of erection
The penis is an unpaired organ externally covered by easily displaceable skin. Its internal framework is formed by three structures: two corpora cavernosa and one corpus spongiosum located beneath them. The urethra runs through the substance of the corpus spongiosum and opens at the glans via a slit-like external orifice.
Blood supply to the organ is provided by branches of the internal and partially the external pudendal artery. The physiological mechanism of erection consists in arterial blood actively filling the corpora cavernosa and corpus spongiosum, giving the organ the necessary rigidity.
Prostate gland
This is an unpaired fibromuscular and glandular organ localized in the lesser pelvis. Anatomically, the prostate consists of two lobes connected by an isthmus. The upper third of the urethra passes through it, and the base of the gland is in close contact with the neck of the urinary bladder and the seminal vesicles.
Histologically, the gland has a lobular structure due to extensions of the outer capsule growing inward. The stroma of the organ is rich in smooth muscle fibers, blood vessels, and nerves, while the parenchyma is formed by numerous glands whose ducts open into the urethra. The prostate secretes a fluid rich in biologically active substances (including hormones), which becomes an important component of semen.
Developmental anomalies and differentiation disorders
Developmental pathologies can affect the anatomy of internal organs. Such defects include monorchism (congenital absence of one testis) and cryptorchidism (failure of the testes to descend into the scrotum).
Disorders of sexual differentiation manifest as the presence of intermediate-type external genitalia in a newborn. These include:
- True hermaphroditism: presence of ovotestis (a single structure containing both testicular and ovarian tissues) or different gonads on each side.
- Male pseudohermaphroditism: incomplete masculinization with a male karyotype, arising from impaired androgen synthesis or testicular dysgenesis.
Impact of chromosomal abnormalities
Sex chromosome abnormalities often lead to delayed sexual development, infertility, and impaired formation of secondary sexual characteristics. Several specific genetic syndromes are distinguished in men:
- Klinefelter syndrome (47,XXY karyotype): accompanied by tall stature, eunuchoid body proportions, and testicular hypoplasia (small size).
- 47,XYY karyotype: characterized by tall stature, aggressiveness, adaptation disorders, and delayed speech development.
- Fragile X syndrome: manifests as intellectual disability and macroorchidism (pathologically enlarged testes).
Class and exam questions
What is cryptorchidism and what consequences does it lead to?
This is a congenital anomaly in which one or both testes fail to descend into the scrotum, remaining in the abdominal cavity or inguinal canal. Bilateral cryptorchidism often leads to infertility due to degeneration of the germinal epithelium and impaired spermatogenesis.
What is the difference between true and false hermaphroditism?
In true hermaphroditism, an individual possesses both testicular and ovarian tissues. Male pseudohermaphroditism is characterized by incomplete masculinization in the presence of a male karyotype due to testicular dysgenesis or a defect in androgen synthesis.
How to distinguish a male pelvis from a female pelvis using bony landmarks?
The male pelvis is narrower and longer compared to the female pelvis. The main distinguishing feature is the angle between the inferior rami of the pubic bones: in men, it forms a subpubic angle of 70–75°, whereas in women, the pubic arch is greater than 90°.
What else to study on this topic
- Instrumental and laboratory diagnostics of gonadal function
- Boundaries and bony structures of the lesser and greater pelvis
- Female pseudohermaphroditism and causes of virilization
- Ovarian developmental anomalies and Turner syndrome
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