The male reproductive system is a complex network of organs and glands working together to produce, nourish, and deliver sperm. From the in the to the accessory glands, each component plays a crucial role in fertility and sexual function.
Hormonal regulation orchestrates the intricate process of , while the composition of ensures sperm survival. Understanding these processes is key to grasping male reproductive health and potential issues that may arise.
Male reproductive system anatomy
Testes and scrotum
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Testes are the male gonads that produce sperm and male sex hormones, primarily
Suspended in the scrotum, which maintains the optimal temperature for spermatogenesis
Scrotum is a skin-covered sac that hangs outside the body to keep the testes cooler than core body temperature
Cremaster muscle in the scrotum can contract to pull the testes closer to the body for warmth or relax to allow them to hang lower for cooling
Epididymis, vas deferens, and ejaculatory ducts
is a highly coiled tube that sits atop each testis and stores and matures sperm
Connects the testis to the
Sperm mature and gain motility as they pass through the epididymis
Vas deferens is a muscular tube that transports mature sperm from the epididymis to the during
Also known as the ductus deferens
Passes through the inguinal canal and into the pelvic cavity
Ejaculatory ducts are formed by the union of the vas deferens and the duct from the seminal vesicle
Empty into the
Carry sperm and during ejaculation
Urethra and penis
Urethra is a tube that runs through the and carries both urine and semen, though not simultaneously
Sphincter muscle contracts during ejaculation to prevent urine from mixing with semen
Divided into prostatic, membranous, and spongy portions
Penis is the male copulatory organ
Consists of erectile tissue (corpora cavernosa and corpus spongiosum) that fills with blood during sexual arousal, causing an erection
Glans penis at the tip contains a high concentration of nerve endings
Foreskin (prepuce) is a fold of skin that covers the glans penis in uncircumcised males
Spermatogenesis and hormonal regulation
Stages of spermatogenesis
Spermatogenesis is the process of sperm production that occurs in the seminiferous tubules of the testes
Begins at puberty and continues throughout a man's life
Takes approximately 64-74 days to complete
, the immature germ cells, line the seminiferous tubules
Undergo mitosis to maintain their population and produce
Primary spermatocytes undergo meiosis I to produce
Secondary spermatocytes then quickly undergo meiosis II to produce
Spermatids differentiate into mature (sperm) through the process of
Involves the formation of the acrosome, condensation of the nucleus, and development of the tail
support and nourish the developing sperm throughout the process
Hormonal regulation of spermatogenesis
Testosterone, produced by the Leydig cells in the testes, is essential for spermatogenesis
Acts on the Sertoli cells, which nourish and support the developing sperm
Maintains libido and secondary sexual characteristics
and regulate testosterone production and spermatogenesis through a
Hypothalamus releases (GnRH), which stimulates the anterior pituitary
Anterior pituitary releases (FSH) and (LH)
FSH stimulates Sertoli cells to support spermatogenesis, while LH stimulates Leydig cells to produce testosterone
High levels of testosterone provide negative feedback to the hypothalamus and anterior pituitary, reducing GnRH, FSH, and LH secretion
Semen composition and ejaculation
Semen components and their functions
Semen, also known as seminal fluid, is the fluid that is ejaculated during sexual activity
Contains sperm and secretions from the , , and
Provides a protective and nutritive medium for sperm
Seminal vesicles contribute about 60% of the semen volume
Their alkaline secretions contain , which provides energy for the sperm
Also contain , which stimulate uterine contractions to aid in sperm movement
Prostate gland contributes about 30% of the semen volume
Its slightly acidic secretions contain enzymes, such as (PSA), which help to liquefy the semen and enhance sperm motility
Also contains zinc, citric acid, and other substances that support sperm function
Bulbourethral glands secrete a clear, alkaline fluid
Neutralizes any residual acidity in the urethra from urine
Lubricates the tip of the penis during sexual arousal
Ejaculation process
Ejaculation is the expulsion of semen from the urethra
Occurs in two phases: emission and expulsion
involves the smooth muscles of the vas deferens, seminal vesicles, and prostate contracting to push semen into the urethra
Bladder neck sphincter contracts to prevent retrograde ejaculation into the bladder
involves the rhythmic contraction of the bulbocavernosus muscle
Forcefully expels semen from the urethra
Accompanied by a feeling of orgasm due to the release of and
Prostate and accessory glands
Prostate gland
Prostate gland is a walnut-sized gland located inferior to the urinary bladder
Surrounds the urethra
Contributes secretions to the semen
Prostatic fluid is slightly acidic and contains enzymes, such as prostate-specific antigen (PSA)
Helps to liquefy the semen after ejaculation, allowing sperm to swim more freely
Also contains zinc, citric acid, and other substances that support sperm function
Disorders of the prostate gland can affect male reproductive and urinary function
(BPH) is a non-cancerous enlargement of the prostate that can cause urinary difficulties
is a malignant growth in the prostate that can spread to other parts of the body
Regular prostate screenings are important for early detection and treatment of these conditions
Seminal vesicles and bulbourethral glands
Seminal vesicles are a pair of glands located posterior to the urinary bladder
Produce a large portion of the seminal fluid
Secretions contain fructose for sperm nutrition, prostaglandins to stimulate uterine contractions, and other substances that enhance sperm survival and motility
Bulbourethral glands, also known as Cowper's glands, are pea-sized glands located inferior to the prostate on either side of the urethra
Secrete a clear, alkaline fluid that neutralizes residual urine acidity in the urethra
Provide lubrication for the tip of the penis during sexual arousal
Secretions may appear as pre-ejaculate (pre-cum) during sexual stimulation