Male Reproductive Anatomy Quiz

Male Reproductive System Overview

• The male reproductive system's primary functions are producing gametes (sperm) and hormones.
• The reproductive structures include external genitalia and internal genitalia.

Male Reproductive System Anatomy Overview - External Genitalia

• Penis: Contains erectile tissue, deposits sperm into the vagina.
• Urethra: Conducts semen to the exterior.
• Scrotum: Supports and surrounds the testes.

Male Reproductive System Anatomy Overview - Internal Genitalia

• Testes: Produce sperm and hormones.
• Epididymis: Site of sperm maturation.
• Ductus Deferens (Vas Deferens): Conducts sperm between the epididymis and prostate.
• Seminal Glands (Seminal Vesicles): Secrete fluid that makes up a large portion of semen volume.
• Prostate: Secretes fluid and enzymes.
• Bulbourethral Glands: Secretes fluids to lubricate the tip of the penis.

Male Reproductive System Anatomy Overview - Path of Sperm

• Sperm is produced in the testes.
• It travels to the epididymis.
• Then through the ductus deferens.
• Through the ejaculatory duct to the urethra.
• Accessory organs secrete fluids into the reproductive tract along the way.

Male Reproductive System Anatomy Overview - Scrotum and Associated Structures

• The scrotum is an outpouching of the abdomen that houses and supports the testes.
• The scrotal septum separates the right and left cavities.
• It's marked by a thickening called the raphe of the scrotum.
• The dartos and cremaster muscles regulate testicular temperature.

Male Reproductive System Anatomy Overview - Spermatic Cords

• Spermatic cords extend through the inguinal canals.
• They contain the ductus deferens, blood vessels, nerves and lymphatic vessels.
• The superficial inguinal ring is the entrance into the inguinal canal.

Male Reproductive System Anatomy Overview - Testes (Testicles)

• Testes have a length of 5 cm, width of 3 cm and a thickness of 2.5 cm.
• Each weighs 10-15 grams.
• They develop within the abdominal cavity adjacent to the kidneys.
• Connective tissue bands pull the testes into the scrotum during fetal development (about 7 months).
• The tunica vaginalis is a serous membrane derived from the peritoneum that partially covers the testes.

Male Reproductive System Anatomy Overview - Testes (Testicles) - Tunica Albuginea

• A dense, white and irregular connective tissue capsule deep to tunica vaginalis.
• It extends inward to form septa creating lobules.
• Each lobule contains 2-3 seminiferous tubules where spermatogenesis takes place.

Male Reproductive System Anatomy Overview - Testes (Testicles) - Cells of the Seminiferous Tubules

• Sustentacular Cells (Sertoli Cells): Extend from basement membrane to the lumen of seminiferous tubules; they protect, support, nourish, and phagocytize developing sperm. They also produce fluid that helps transport sperm, secrete hormone (inhibin) and form the blood-testis barrier.
• Interstitial Endocrine Cells (Leydig cells): Produce androgens (like testosterone) and androstenedione (important sex hormones).

Male Reproductive System Anatomy Overview - Testes (Testicles) - Cells of the Seminiferous Tubules - Pathways of Sperm

• Wall of the seminiferous tubules includes spermatogonia, spermatocytes, spermatids - which develop into mature sperm cells.

Male Reproductive System Anatomy Overview - Spermatogenesis

• The development of sperm takes 65-75 days.
• Millions of sperm are produced every day.
• The four basic steps are:
  • Creation of spermatogonia through mitosis
  • Meiosis to make sperm
  • Spermiogenesis to create functional sperm
  • Spermiation (release from nurse cells into the tubule lumen).

Male Reproductive System Anatomy Overview - Structure of Sperm

• Head: Contains the nucleus with 23 chromosomes and the acrosome which contains enzymes needed to penetrate the ovum.
• Neck: Connects the head to the mid piece.
• Middle Piece: Contains mitochondria needed for ATP for tail movement.
• Tail: Whip-like organelle for sperm movement.

Male Reproductive System Anatomy Overview - Spermatogenesis - Capacitation

• This is the process enabling sperm to become fully motile and functional.
• It usually occurs in two steps:
  • Mixing sperm with seminal gland secretions makes them motile.
  • Exposure to the female reproductive tract enables fertilization capability.

Male Reproductive System Anatomy Overview - Recap - Male Reproductive Tract

• The sperm travels through the epididymis, ductus deferens, ejaculatory duct and finally the urethra.
• Along the pathway, seminal vesicles, prostate and bulbourethral glands add fluids to become semen.

Male Reproductive System Anatomy Overview - Histology of Epididymis

• The epididymis is lined with pseudostratified columnar epithelium with stereocilia to increase surface area for sperm absorption.
• A layer of smooth muscle propels sperm through peristaltic contractions.

Male Reproductive System Anatomy Overview - Ductus Deferens

• The ductus deferens is lined with pseudostratified columnar epithelium covered by a thick coating of muscle to propel sperm by peristaltic contractions.

Male Reproductive System Anatomy Overview - Ejaculatory Ducts

• These are the unions of seminal vesicle ducts and ductus deferens.
• They eject sperm into the prostatic urethra.

Male Reproductive System Anatomy Overview - Urethra

• The urethra is the shared terminal duct of the reproductive and urinary systems.
• It's the passageway for semen and urine.
• It has three parts: prostatic, membranous, and spongy (cavernous).

Male Reproductive System Anatomy Overview - Seminal Glands

• These glands are located between the posterior wall of the urinary bladder and the rectum.
• Their secretion is alkaline, neutralizing the vagina and male urethra.
• The secretions include fructose, prostaglandins, and other components to facilitate sperm viability and motility.
• They produce roughly 60% of the semen volume.

Male Reproductive System Anatomy Overview - Prostate Gland

• The prostate encircles the urethra as it leaves the bladder.
• It's roughly the size of a golf ball.
• Secretions contain seminalplasmin, proteolytic enzymes, citric acid, and sperm ATP production.
• It contributes about 20-30% of the semen volume.

Male Reproductive System Anatomy Overview -

• The bulbourethral glands are located at the base of the penis.
• Each gland's duct empties into the urethra.
• They secrete an alkaline mucus, neutralising acids in the urethra and lubricating the tip of the penis.

Male Reproductive System Anatomy Overview - Semen

• Semen contains sperm and seminal fluid from the accessory glands.
• It's slightly alkaline and milky in appearance.
• A normal ejaculate contains 50-150 million sperm per ml.
• Immediately after ejaculation, semen coagulates, liquefies after 10 - 20 minutes.

Male Reproductive System Anatomy Overview - Penis - Two Functions

• Transports urine out of the body.
• Delivers semen into the vagina during intercourse.

Male Reproductive System Anatomy Overview - Penis - Structure of the Penis

• The penis includes a root, a body (shaft), and a glans (head).

Male Reproductive System Anatomy Overview - Penis - Erectile Tissue

• The penis's body (shaft) has three erectile tissue masses (corpora cavernosa and corpus spongiosum) filled with vascular spaces (sinusoids).
• In a relaxed state, this restricts blood flow.

Male Reproductive System Anatomy Overview - Penis - Phases of Sexual Response (Arousal)

• Erotic thoughts or stimulation increase parasympathetic stimulation, releasing nitric oxide.
• This causes arterial dilation, increased blood flow, and engorging and compressing the vascular channels.
• Blood is trapped, resulting in an erection.

Male Reproductive System Anatomy Overview - Penis - Emission or Ejaculation

• Sympathetic activation triggers peristaltic contractions in the ductus deferens.
• Sperm is pushed into the prostatic urethra.
• Contractions in the seminal glands and prostate mix secretions with sperm to form semen.

Male Reproductive System Anatomy Overview - Penis - Impotence (ED)

• The inability to achieve or maintain an erection.
• Possible causes are vascular changes, interference with neural commands, psychological factors, and certain medications.

Male Reproductive System Anatomy Overview - Hormones and the Male Reproductive System - Hypothalamic Regulation

• The hypothalamus secretes gonadotropin-releasing hormone (GnRH) at a steady pace.
• GnRH targets the anterior pituitary gland.

Male Reproductive System Anatomy Overview - Hormones and the Male Reproductive System - Anterior Pituitary

• Responds by producing two gonadotropins: luteinizing hormone (LH), and follicle-stimulating hormone (FSH).

Male Reproductive System Anatomy Overview - Hormones and the Male Reproductive System - Luteinizing Hormone (LH)

• LH targets the interstitial cells (Leydig cells) in the testes.
• Leydig cells secrete testosterone and other androgens.
• Testosterone levels are controlled by negative feedback, with high testosterone inhibiting GnRH release.

Male Reproductive System Anatomy Overview - Hormones and the Male Reproductive System - Follicle-Stimulating Hormone (FSH)

• FSH targets nurse cells (Sertoli cells) in the seminiferous tubules
• Sertoli cells promote spermatogenesis and spermiogenesis.
• Release of androgen-binding protein (ABP), which binds testosterone and keeps it in area of developing sperm.
• Sertoli cells secrete inhibin which inhibits FSH.
• The whole process provides feedback control of spermatogenesis.

Male Reproductive System Anatomy Overview - Hormones and the Male Reproductive System - Testosterone

• The principal androgen.
• Synthesized from cholesterol in interstitial cells (Leydig cells).
• Lipid-soluble, released by interstitial cells to interstitial fluid and blood.
• Controlled by negative feedback.
• External genitalia and prostate transform testosterone to dihydrotestosterone (DHT).

Male Reproductive System Anatomy Overview - Hormones and the Male Reproductive System - Prenatally

• Testosterone stimulates the development of the male reproductive system and the descent of testes.
• Dihydrotestosterone (DHT) stimulates the development of external genitalia.
• Brain testosterone converts to estrogen, supporting some brain development.

Male Reproductive System Anatomy Overview - Hormones and the Male Reproductive System - After Puberty

• Maintains libido and behaviors related to it.
• Stimulates bone and muscle growth.
• Maintains male secondary characteristics.
• Keeps accessory glands and organs of the male reproductive system functioning.

Male Reproductive System Anatomy Overview - Hormones and the Male Reproductive System - Effects of Dihydrotestosterone (DHT)

• Testosterone converts to DHT; only ~10% circulating testosterone.
• DHT acts on the same receptors as testosterone in certain tissues which are more sensitive to DHT (external genitalia and prostate).

Test your knowledge about the male reproductive system, specifically focusing on the epididymis and its functions. This quiz includes questions about the anatomy and the secretory glands involved in the male reproductive tract.