A presentation on

Male Reproductive System

BSc II Semester IV

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M. H. Karennavar

Associate Professor in Zoology

Raje Ramrao College Jath

Dist Sangli Maharashtra

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�The Reproductive System- Male

The Reproductive System

• Gonads – primary sex organs
• Testes in males
• Ovaries in females
• Gonads produce gametes (sex cells) and secrete hormones
• Sperm – male gametes
• Ova (eggs) – female gametes

Developmental Aspects of the Reproductive System

• Gender is determined at fertilization
• Males have XY sex chromosomes
• Females have XX sex chromosomes
• Gonads do not begin to form until the eighth week

Developmental Aspects of the Reproductive System

• Testes form in the abdominal cavity and descend to the scrotum one month before birth
• The determining factor for gonad differentiation is testosterone

Developmental Aspects of the Reproductive System

• Reproductive system organs do not function until puberty
• Puberty usually begins between ages 10 and 15
• The first menses usually occurs about two years after the start of puberty
• Most women reach peak reproductive ability in their late 20s

Developmental Aspects of the Reproductive System

• Menopause occurs when ovulation and menses cease entirely
• Ovaries stop functioning as endocrine organs
• There is a no equivalent of menopause in males, but there is a steady decline in testosterone

Male Reproductive System

Male Reproductive System

• Testes
• Duct system
• Epididymis
• Ductus deferens
• Urethra

Male Reproductive System

• Accessory organs
• Seminal vesicle
• Prostate gland
• Bulbourethral gland
• External genitalia
• Penis
• Scrotum

Testes

• Coverings of the testes
• Tunica albuginea – capsule that surrounds each testis

Testes

• Coverings of the testes (continued)
• Septa – extensions of the capsule that extend into the testis and divide it into lobules

Testes

• Each lobule contains one to four seminiferous tubules
• Tightly coiled structures
• Function as sperm-forming factories
• Empty sperm into the rete testis
• Sperm travels through the rete testis to the epididymis
• Interstitial cells produce testosterone

Interstitial cells: produce testosterone

Sertoli cells ( nurse cells ) support sperm production.

Epididymis

• Comma-shaped, tightly coiled tube
• Found on the superior part of the testis and along the posterior lateral side
• Functions to mature and store sperm cells (at least 20 days)
• Expels sperm with the contraction of muscles in the epididymis walls to the vas deferens (ductus deferens)

Male Reproductive System

Ductus Deferens (Vas Deferens)

• Carries sperm from the epididymis to the ejaculatory duct
• Passes through the inguinal canal and over the bladder
• Moves sperm by peristalsis
• Spermatic cord – ductus deferens, blood vessels, and nerves in a connective tissue sheath

Ductus Deferens (Vas Deferens)

• Ends in the ejaculatory duct which unites with the urethra
• Vasectomy – cutting of the ductus deferens at the level of the testes to prevent transportation of sperm

Spermatic Cord and Inguinal Canal

Contents of Spermatic cord:

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• Cremasteric muscle- adjusts testes to control temperature

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• Testicular ( gonadal) artery

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• Ductus deferens

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• Nerves

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• Veins

 Development and descent of testes and formation of spermatic cord. 

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A: Two months in utero. 

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B: Three months in utero. 

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C: At birth.

Urethra

• Extends from the base of the urinary bladder to the tip of the penis
• Carries both urine and sperm
• Sperm enters from the ejaculatory duct

Urethra

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• Regions of the urethra
• Prostatic urethra –surrounded by prostate
• Membranous urethra – from prostatic urethra to penis
• Spongy (penile) urethra – runs the length of the penis

Seminal Vesicles

• Located at the base of the bladder
• Produces a thick, yellowish secretion (60% of semen)
• Fructose (sugar)
• Vitamin C
• Prostaglandins
• Other substances that nourish and activate sperm

Prostate Gland

• Encircles the upper part of the urethra
• Secretes a milky fluid
• Helps to activate sperm
• Enters the urethra through several small ducts

Bulbourethral Glands

• Pea-sized gland inferior to the prostate
• Produces a thick, clear mucus
• Cleanses the urethra of acidic urine
• Serves as a lubricant during sexual intercourse
• Secreted into the penile urethra

Semen

• Mixture of sperm and accessory gland secretions
• Advantages of accessory gland secretions
• Fructose provides energy for sperm cells
• Alkalinity of semen helps neutralize the acidic environment of vagina
• Semen inhibits bacterial multiplication
• Elements of semen enhance sperm motility

External Genitalia

• Scrotum
• Divided sac of skin outside the abdomen
• Maintains testes at 3°C lower than normal body temperature to protect sperm viability

External Genitalia

• Penis
• Delivers sperm into the female reproductive tract
• Regions of the penis
• Shaft
• Glans penis (enlarged tip)
• Prepuce (foreskin)
• Folded cuff of skin around proximal end
• Often removed by circumcision

External Genitalia

• Internally there are three areas of spongy erectile tissue around the urethra

Spermatogenesis

• Production of sperm cells
• Begins at puberty and continues throughout life
• Occurs in the seminiferous tubules

Processes of Spermatogenesis

• Spermatogonia (stem cells) undergo rapid mitosis to produce more stem cells before puberty
• Follicle stimulating hormone (FSH) modifies spermatogonia division
• One cell produced is a stem cell
• The other cell produced becomes a primary spermatocyte

Processes of Spermatogenesis

• Primary spermatocytes undergo meiosis
• Haploid spermatids are produced

Processes of Spermatogenesis

• Spermiogenesis
• Late spermatids are produced with distinct regions
• Head – contains DNA

covered by the acrosome

• Midpiece
• Tail
• Sperm cells result after maturing of spermatids
• Spermatogenesis takes 64 to 72 days

The acrosome contains digestive enzymes to penetrate the outer covering of the egg

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Mitochondria produce energy from secretions which is used to move the flagellum

Match the following:

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1. Interstitial Cells
2. Nurse cells
3. Seminiferous Tubules
4. Epididimys
5. Spermatic cord

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1. Contains testicular artery, nerves, ductus deferens
2. Support sperm formation
3. Produce testosterone
4. Site of sperm formation
5. Site of sperm maturation.

Conversion of haploid spermatids to spermatozoa is specifically called __________.

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The area of the sperm cell that contains many mitochondria is the __________.

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_________ acts upon the __________ to encourage the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH).

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1. Gonadotropin-releasing hormone (GnRH); Sertoli (nurse)cells

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• Testosterone; anterior pituitary

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• Testosterone; Sertoli (nurse) cells

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• Gonadotropin-releasing hormone (GnRH); anterior pituitary

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