Male Anatomy

Male anatomy - sagittal view 1. Testis: Produce and store millions of sperm cells. Makes testosterone 2. Epididymis: Coiled tubes that hold sperm for 2-3 months until they mature. 5 4 3. Vas deferens: Tube that passes mature sperm from epididymis to penis. 3 4. Prostate gland: Provides 30-35% of the seminal fluid. 2 5. Seminal vesicles: Sac-like structures attached to the vas deferens that produce 60% of seminal fluid. 1

Cowper’s gland (also called the bulbourethral gland) produces the fluid that is released from the penis before ejaculation. This fluid “flushes out” the urethra before the arrival of semen.

6. Scrotum: Pouch-like structure outside the body that maintain the testicles at a certain temperature. 7. Bladder: Organ that collects/stores urine. 7 8. Urethra: Channel that carries semen and urine out of the body 10 8 9. Penis: Made up of spongy tissue that can expand and contract. 9 10. Anus: Opening from which feces leaves the body. 6

Semen Production & Ejaculation 4. Seminal vesicle and prostate gland add fluid to make semen 3. Sperm leave through vas deferens 5. Semen leaves through urethra 2. Sperm mature in epididymis 1. Sperm are made in the testicles

Sperm production Beginning at puberty, the pituitary gland stimulates the testicles to start producing testosterone, the male sex hormone

Testosterone initiates sperm production Sperm production starts in seminiferous tubules, organized into lobules

Cross section of seminiferous tubules

Leydig cells produce testosterone

Germ cells are any cells that give rise to gametes (sex cells) Male germ cells are called spermatogonia (spermatogonium is singular) Every day, about 25 million spermatogonia begin the process to become mature sperm

Spermatogonia enter meiosis (begin to mature and divide) to become primary spermatocytes Primary spermatocytes split into two cells called secondary spermatocytes Now the two secondary spermatocytes each split to become four spermatids cells

Spermatogonia If 25 millions spermtogonia begin the meiosis process every day… that means 100 million sperm are made every day! primary spermatocytes 2 secondary spermatocytes 4 spermatids

Anatomy of sperm The nucleus contains all the genetic information from the male body The acrosome covers the nucleus. The job of the acrosome is to penetrate the protective layer of the ovum The flagellum whips back and forth to move the sperm towards the ovum

Once mobile, the sperm travel from the seminiferous tubules into the rete testis

From the rete testis, the sperm enter the epididymis where they are stored until they finish maturing and are ejaculated

Cross section of the penis The corpora cavernosa and corpus spongiosum are erectile tissue. Inside these chambers have a lot of blood vessels. When a person is aroused the vessels fill with blood and expand  causing an erection.

Base or root of penis Shaft of penis Head or glans of penis

Circumcision Whether a person is circumcised depends on their family, culture, religion, and personal preferences.