Midwest Reproductive Center

Basic Male Biology

Understanding Basic Male Biology

As your fertility specialist, Dr. Dan Gehlbach will likely recommend resources such as this website as you progress from consultation to male infertility diagnosis and treatment. Years may have passed since high school biology, so a refresher on anatomy and the male reproductive system will prove helpful in the days to come.


Understanding basic male biology will empower you to fully engage in treatment decisions. Dr. Gehlbach may begin your male infertility consult with an overview of the mechanics at work in conceiving a baby.


The success of a male reproductive system hinges

on 3 key functions:

Sperm (reproductive cells) production; structural performance of the penis, scrotum and testes; and hormonal signals that control the entire reproductive system.


Sperm Production


5 Stages of a Sperm Lifecycle Sperm is produced in the leydig cells, located in a man’s testes.

  1. The immature sperm is generated in response to Follicle Stimulating Hormone (FSH), Luteinizing Hormone (LH) and testosterone.
  2. Sperm then passes into the epididymus, where it is stored for several days.
  3. Over 9 to 10 weeks, the sperm becomes mature so that it is ready for the next ejaculation.
  4. During an ejaculation, sperm is pushed into the ejaculatory duct where other fluids are added by the various glands.
  5. Sperm is then ejaculated by muscular movements and pushed forward into the vagina.

How many sperm do you suppose the average man ejaculates at one time?

A. 70 million sperm

B. 150 million sperm

C. 15 million sperm


The answer is (A) 70 million sperm. A

concentration of fewer than 20 million

sperm will likely cause you to see a

fertility specialist.


Sperm is made in the testes, contained

within the scrotum and transported

through the vas deferens tubes to a

“holding tank” called the seminal vesicles.

This is where sperm is mixed with

protective fluid to become semen.


You may present with an adequate sperm count, but

still encounter trouble conceiving. Other issues can

occur because sperm must also travel, or swim,

through a woman’s cervix, uterus and fallopian tubes

to fertilize an egg.


In a male infertility workup, fertility specialists like Dr. Gehlbach evaluate sperm count, motility (movement) and morphology (size and shape).


Male Reproductive Anatomy


  • Reproductive Organs

The penisscrotum and testicles (testes) work together to produce, protect and release sperm into ducts. Ducts serve as a plumbing system to transport sperm.

  • Ducts

Epididymis tubes on each testicle store, transport and incubate sperm; the vas deferens tube continues the journey by carrying sperm to another tube — the urethra, where it will be ejaculated during sexual climax from the penis. Ejaculatory ducts expel fluid into the urethra.

  • Glands

Seminal vesicles are responsible for nourishing sperm with a fructose-based fluid; the prostate serves the same purpose, and also resides on the ejaculate’s route from the urethra; and bulbourethral (Cowper’s) glands act like a cleaning agent, adding a lubricating, slippery liquid to the ejaculate fluid to neutralize trace amounts of urine. (An erect penis temporarily prevents urine from entering the urethra.)


You may need to be seen by a urologist to uncover the underlying causes of male infertility. Rest assured that many treatment options (intrauterine insemination and in-vitro fertilization, for instance) exist to improve your chances of conceiving a baby, even when physical barriers are present.


Male Sex Hormones

Your brain houses the male reproductive system’s control center. The pituitary gland signals the body to release hormones that are instrumental in producing and regulating sperm production.


Gonadotropin Releasing Hormones (GRH) create two hormones:


  • Luteinizing Hormones (LH) stimulate the cells of the testes to make the male sex hormone testosterone. Testosterone aids in the development of male characteristics: facial hair, muscle and bone mass, voice changes and sex drive.
  • Follicle-Stimulating Hormones (FSH), with the help of testosterone, produce sperm.


Hormonal imbalances that interfere with sperm production can lead to male infertility.


One-third of all cases of infertility can be attributed to male factors, so taking proactive steps to identify the problem will help you avoid months of frustration and failed attempts at conceiving a baby.


Each intricate part of the male reproductive system plays a critical role in fertility. If you have tried for longer than 1 year to get pregnant, or 6 months when the female partner is older than 35, consider scheduling a consultation with a fertility specialist like Dr. Gehlbach.