Male Reproductive system

Male Reproductive system



At the end of this lecture, student will be able to

• List the organs of male reproductive system

• Describe the structure of male reproductive system

• Describe the process of spermatogenensis

• Explain the negative feedback control on blood levels of testosterone


• Reproduction – process by which new individuals of a species are produced and the genetic material is passed from generation to generation

The organs of reproduction are grouped as

• Gonads (produce gametes)

• Ducts (transport and store gametes)

• Accessory sex glands (produce materials that support gametes) and

• Supporting structures (have various roles in reproduction)

Male reproductive system

Sagittal section of male reproductive system


Anatomy of male reproductive system


• A sac that hangs from the root of the penis 

• Consists of loose skin and underlying subcutaneous layer

• Supports the testes

• Single pouch of skin separated into lateral portions by a median ridge called the raphe

Scrotal septum divides the scrotum into two sacs, each containing a single testis

Septum – made up of a subcutaneous layer and muscle tissue, the dartos muscle

• Each testis in the scrotum is associated with cremaster muscle, a series of small bands of skeletal muscle

Testes/ Testicles

• Paired oval glands (gonads) in the scrotum

– Seminiferous tubules – sperm cells are made

– Sertoli cells (sustentacular cells)- nourish sperm cells and secrete inhibin

– Leydig (interstitial) cells, produce the male sex hormone testosterone

• Testes descend into the scrotum through the inguinal canals

• Failure of the testes to descend, cryptorchidism

Sertoli cells – secrete androgen-binding protein (ABP) à binds to testosterone àkeeps its concentration high in the seminiferous tubule

– Secrets inhibin à inhibition of FSH helps à regulate the rate of spermatogenesis.

• Testosterone

  Controls the growth, development, and maintenance of sex organs

  Stimulates bone growth, protein anabolism, sperm maturation

  Stimulates development of masculine secondary sex characters

System of ducts

• Ducts of the Testis

– Seminiferous tubules

– Straight tubules

– Rete testis

• Sperm flow out of the testes through the efferent ducts

• Ductus epididymis – site of sperm maturation and storage

• Ductus (vas) deferens

– Stores sperm

– Propels them toward the urethra during ejaculation

• Ejaculatory duct

– Union of the duct from the seminal vesicle and vas deferens

– Passage for ejection of sperm and secretions of the seminal vesicles into the first portion of the urethra, the prostatic urethra

• Urethra in males is subdivided into 3 portions:

– Prostatic

– Membranous

– Spongy (penile) urethra- ends at the external urethral orifice

Sagittal section of a testis showing seminiferous tubules


Accessory Sex Glands


Seminal Vesicles/Seminal glands

– Convoluted pouch like structures

– Posterior to the base of the urinary bladder

– Anterior to the rectum

Secrete alkaline, viscous fluid

– Neutralize acid in the female reproductive tract

– Fructose for ATP production by sperm

– Sperm motility and viability

– Semen coagulate after ejaculation

Prostate gland

• A single, doughnut-shaped gland

• About the size of a golf ball; Inferior to the urinary bladder

• Surrounds the prostatic urethra

• Secretes a milky, slightly acidic fluid (pH 6.5) contains

– Citric acid in prostatic fluid – ATP production via the Krebs cycle

– Proteolytic enzymes – break down the clotting proteins from the seminal vesicles

– Seminal plasmin in prostatic fluid- an antibiotic, destroy bacteria

Bulbourethral Glands

• Paired bulbourethral glands/Cowper’s glands; about the size of peas.

• Inferior to the prostate on either side of the membranous urethra

• Their ducts open into the spongy urethra

• Secrete an alkaline fluid into the urethra

– Protects the passing sperm by neutralizing acids from urine

• Secrete mucus

– Lubricates the end of the penis and the lining of the urethra

– Decreases the no. Of sperm damaged during ejaculation


• Contains the urethra

• Passageway for the ejaculation of semen and the excretion of urine

• Consists of

– A body

– Glans penis

– A root

Body of the penis, composed of 3 cylindrical masses of tissue, each surrounded by fibrous tissue, tunica albuginea

– Two dorsolateral masses, corpora cavernosa penis

– Smaller midventral mass, the corpus spongiosum penis, contains spongy urethra

Glans penis

• Enlarged acorn-shaped region

• At the distal end of the corpus spongiosum penis

   Its margin is the corona

• Covering the glans in an uncircumcised penis is the loosely fitting prepuce or foreskin

Root of the penis – attached portion

Has – Bulb of the penis

– The expanded portion of the base of the corpus spongiosum crura of the penis

Internal structure of the penis



• Mixture of sperm and seminal fluid

• Consists of the secretions of the seminiferous tubules, seminal vesicles, prostate, and bulbourethral glands

• Provides the fluid in which sperm are transported

• Supplies nutrients

• Neutralizes the acidity of the male urethra and the vagina

Internal structure of the penis



• Process whereby immature spermatogonia develop into sperm

• Occurs in the testes

• Takes 65–75 days

• Sequence includes

– Meiosis I

– Meiosis II

– Spermiogenesis

• Forms 4 haploid sperm (spermatozoa) from each primary spermatocyte

• Mature sperm consist of a head and a tail

• Function – fertilize a secondary oocyte

Hormonal Control of the Testes

• Release of FSH is stimulated by GnRH and inhibited by inhibin

• Release of LH is stimulated by GnRH and inhibited by testosterone.


Negative feedback control of blood level of testosterone


Gonadotrophs of the anterior pituitary produce luteinizing hormone (LH).


• Reproduction is the process by which new individuals of a species are produced and the genetic material is passed from generation to generation

• Reproductive organs – Gonads, Ducts, Accessory sex glands andS upporting structures

• Male structures of reproduction include the testes, ductus epididymis, ductus (vas) deferens, ejaculatory duct, urethra, seminal vesicles, prostate, bulbourethral (Cowper’s) glands, and penis

• Spermatogenesis, occurs in the testes, is the process whereby immature spermatogonia develop into sperm

• Testosterone controls the growth, development, and maintenance of sex organs; stimulates development of masculine secondary sex characteristics

• Levels of testosterone in blood is controlled by negative feedback mechanism

Also, Visit:

B. Pharma Notes | B. Pharma Notes | Study material Bachelor of Pharmacy pdf

B. Pharma Handwritten Notes

B. Pharma PDF Books

B. Pharma Lab Manual

D. Pharma Lab Manual

B. Pharma 8th Semester Previous Year Question Paper

D. Pharma Notes

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