BIO 004 · Human Anatomy
The Male Reproductive System
Block 4 · Module 5: The Reproductive System, Male
A reference for the male reproductive system video and lab. This page covers the scrotum and testes, the duct system and the path of sperm, the structure of a sperm cell, the accessory glands, and the penis. The focus is on the structures and the job each one does.
How to use this sheet Toggle the toolbar above. Notes prints the full reference for review. Study prints as a fill-in-the-blank worksheet. Print it, then write each definition while you watch the video or read your book. Quiz me is on-screen typing practice: type the term, click Reveal to check yourself. The comparison grids respond to Study and Quiz too, with a Reveal button on each row.
The Foundations video gives you a complete foundational understanding of this topic, enough on its own for a foundational course. Learn it first, then move on to the Deep dive, which adds the majors-level depth for this course.
- Identify the structures of the scrotum and the testes.
- Trace the path of sperm through the duct system.
- Name the accessory glands and the parts of a sperm cell and the penis.
Your pre-work
Work through these the evening before class. None of it is turned in. It is how you learn the material and build your spaced recall.
This is more than a checklist. Ticking these boxes is the start, not the finish. Committing this material to memory and being able to apply it takes considerable time and repeated effort. You are not done when the boxes are checked. Put in the real hours, and keep coming back for frequent recall and review until the material is genuinely yours.
The male reproductive tract
Add a labeled sagittal view of the testis, duct system, glands, and penis.
The testis
Add a labeled view of the lobules, seminiferous tubules, and the tunica layers.
A sperm cell
Add a labeled diagram of the head, acrosome, and the parts of the tail.
The Male Reproductive System, an Overview
The male reproductive system produces sperm and delivers it. Its parts sort into the gonads, a duct system, the accessory glands, and the supporting structures.
- Testesthe male gonads; they produce sperm and secrete hormones
- Duct systemthe epididymis, ductus deferens, ejaculatory ducts, and urethra, which store, mature, and transport sperm
- Accessory glandsthe seminal vesicles, prostate, and bulbourethral glands, which add fluid to form semen
- Supporting structuresthe scrotum and the penis, which help deliver sperm into the female tract
The Scrotum and Testes
The testes hang outside the body in the scrotum, which keeps them a few degrees cooler than the core. Inside each testis, coiled tubules produce the sperm.
- Scrotumthe pouch of skin and subcutaneous tissue that supports the testes; a raphe marks its surface and a scrotal septum divides it within
- Dartos musclethe smooth muscle of the scrotum that wrinkles the skin to reduce heat loss
- Cremaster musclethe skeletal muscle that raises and lowers the testes to regulate their temperature
- Tunica vaginalisthe serous membrane, derived from the peritoneum, that partly covers each testis
- Tunica albugineathe white fibrous capsule that divides each testis into 200 to 300 lobules
- Seminiferous tubulesthe tightly coiled tubes within the lobules where sperm are produced
- Sustentacular cellsthe Sertoli cells lining the seminiferous tubules; they nourish developing sperm and form the blood-testis barrier
- Interstitial cellsthe Leydig cells between the tubules; they produce testosterone
The Duct System and the Path of Sperm
After they form, sperm travel a fixed series of ducts that store them, mature them, and carry them out.
- Epididymisthe comma-shaped, coiled duct on the testis where sperm are stored and gain motility
- Ductus deferensthe vas deferens; the duct that carries sperm from the epididymis up toward the urethra
- Ejaculatory ductthe short duct formed where the ductus deferens meets the seminal vesicle duct; it empties into the prostatic urethra
- Urethrathe shared final duct; it passes through the prostate, the perineum, and the penis
- Spermatic cordthe bundle that contains the ductus deferens, blood vessels, nerves, and the cremaster muscle
Sperm follow one route from the testis to the outside.
- Seminiferous tubulessperm are produced inside the testis
- Epididymissperm are stored and gain the ability to move
- Ductus deferenssperm are carried up out of the scrotum
- Ejaculatory ductthe ductus deferens joins the seminal vesicle duct
- Urethrasperm pass through the prostatic, membranous, and spongy urethra to the outside
The Structure of a Sperm Cell
A mature sperm cell is built for one job, reaching and entering an oocyte. It has a head and a tail.
- Headthe part of the sperm that holds the nucleus with its 23 chromosomes
- Acrosomethe enzyme-filled cap over the head that helps the sperm penetrate the oocyte
- Neckthe part of the tail just behind the head, containing the centrioles
- Middle piecethe part of the tail packed with mitochondria, which power movement
- Principal piecethe longest part of the tail
- End piecethe tapering terminal part of the tail
The Accessory Glands and Semen
Three sets of accessory glands add fluid to the sperm. The mixture of sperm and these fluids is semen. Compare the glands.
| Gland | What it adds |
|---|---|
| Seminal vesicles | an alkaline fluid rich in fructose that nourishes the sperm; the largest share of semen |
| Prostate | a milky, slightly acidic fluid that helps the sperm stay active |
| Bulbourethral glands | the Cowper's glands; an alkaline mucus that neutralizes urine in the urethra and lubricates |
- Sementhe mixture of sperm and the fluids of the three accessory glands
The Penis
The penis delivers semen and carries the urethra. It is built around three columns of erectile tissue.
- Rootthe attached portion of the penis, containing the bulb and the crura
- Bodythe free, movable portion of the penis
- Glans penisthe enlarged, acorn-shaped tip, an extension of the corpus spongiosum
- Prepucethe foreskin; the loose fold of skin over the glans
- Corpora cavernosathe two dorsal columns of erectile tissue
- Corpus spongiosumthe single ventral column of erectile tissue that surrounds the spongy urethra
- Erectile tissuethe spongy tissue of the columns that fills with blood during an erection
Common Disorders of the Male Reproductive System
Compare the common disorders of the male reproductive system by the structure each one affects.
| Disorder | What it is |
|---|---|
| Cryptorchidism | one or both testes fail to descend into the scrotum |
| Hydrocele | a collection of serous fluid in the tunica vaginalis around a testis |
| Varicocele | an abnormal swelling of the veins that drain the testis |
| Benign prostatic hyperplasia | a non-cancerous enlargement of the prostate that can squeeze the urethra |
| Prostate cancer | a malignant tumor of the prostate gland |
| Testicular cancer | a malignant tumor of the testis |
| Inguinal hernia | a loop of intestine pushes through a weak point in the abdominal wall at the inguinal canal |
See also: The Urinary System for the shared urethra, and The Female Reproductive System, the next page in this block.
Study questions
Work on answering these in writing, in your own words. They are the questions to bring to class, and good practice for the reasoning the exams ask for.
- Trace the path of a sperm cell from where it is made to where it leaves the body, naming each duct.
- Name the accessory glands of the male reproductive system and what each one adds to semen.
- Explain, anatomically, why the testes sit outside the main body cavity.
- Compare the structures that produce sperm with the structures that store and carry them.
Step 2 . Retrieval check
Now explain it back, in your own words.
In 60 words or more, pull together what the video just taught you. Include the key concepts. This is the point where the learning actually sticks. After you submit, your spaced-recall cards for this topic unlock.