Funny Looking Sperm: What You Should Know About Sperm Morphology

Andrew Siegel MD      1/29/2022

Sperm need to be supremely hale and hardy to meet the challenge of their long and arduous odyssey. The one that gets the gold medal is a true Olympian. The entire lot of them are given a jump start advantage with ejaculation–the equivalent of a dive off the blocks–but thereafter are on their own and must be powerful swimmers with tremendous endurance, as capable as Mark Spitz (for you boomers) and Michael Phelps (for you millennials), to finish the marathon from vagina to fallopian tubes.

Thank you Imgflip.com; https://imgflip.com/i/18tvmw; made by Tate Ellison

The first obstacle to the journey of the sperm is the cervical mucus, which can act like an impenetrable net, although at the time of peak female fertility it loosens up and eases its grip, allowing the strongest swimmers access to the womb. Sperm then need to travel about 7-8 inches or so from the cervical opening through the uterus and into the fallopian tubes, the equivalent of a human swimming 100 laps or so of an Olympic pool. In addition to being power swimmers, the sperm need to be capable of tremendous endurance, surviving in the fallopian tubes for up to a week or so.  Only a handful of sperm make it to the finish line, the rest failing to survive because of being trapped in the mucus, entering the incorrect fallopian tube, or perishing along the demanding journey. The handful of survivors that make it to the egg need to retain sufficient energy to power the final sprint enabling penetration of the egg before the other competitors have a chance to do so. Sperm size, shape, and form matters, the topic of today’s entry.

Here’s a bizarre fact:  The vast majority of sperm in any given semen sample are ABNORMAL in appearance: they may be deformed, misshapen, distorted, malformed, contorted, crooked, warped, buckled, disfigured, marred, what some would refer to as “fugly.

According to World Health Organization guidelines, when one’s sperm count and motility are satisfactory, if more than 4% of sperm are normal in appearance, it bodes well for fertility. How insane is it that 4% right is a passing grade!  That was certainly not the case when I went to school! If this was baseball, it would be the equivalent of a batting average of 40 being a good one!  So, don’t be under the misconception (pun intended) that you need many normal appearing sperm to be fertile.

How Can One Be Fertile With So Much Damaged Goods?

How is it that even with 96% abnormal sperm forms you can still be quite fertile?  Well, consider that the average ejaculation contains well over 100 million sperm, so having “only” a few million normal sperm is not so shabby.

Semen Analysis

A microscopic examination of freshly ejaculated sperm is a simple means of assessing male fertility potential. Several parameters are assessed in a semen analysis, including semen volume, sperm count, sperm motility, and sperm morphology. The most common causes of male infertility are low sperm count and/or low sperm motility, but sperm morphology (the physical appearance of sperm) certainly plays a role as well. 

Normal Sperm

A normal sperm cell has an oval-shaped head, an intact midsection and a straight, uncoiled single tail. These attributes enable the sperm to swim capably in a forward direction in the marathon race from vagina to fallopian tube and effectively penetrate the egg. Normal shaped sperm with perfectly shaped heads are most likely to carry healthy DNA and are best suited to penetrate and fertilize the egg.

Funny Looking Sperm

Funny looking sperm with abnormally shaped or multiple heads often carry too many or too few chromosomes. Those with tail abnormalities often lack the motor power for the lengthy journey to the egg. The medical term for large numbers of abnormal sperm is “teratozoospermia.” 

Abnormalities of sperm head, mid-piece, and tail
Mariana Ruiz, CC0, via Wikimedia Commons 

Sperm can have abnormal morphology based upon head size, head shape, number of heads, midsection size and shape, tail size, tail shape, number of tails, and tail positioning.  Some of the abnormalities of morphology include the following: big heads (macrocephaly), small heads (microcephaly), pinheads, tapered heads, narrow heads, de-condensing heads (unraveled DNA filling head), multi-heads, headless, tailless, vacuolated sperm, swollen neck, coiled-tail, and stump tail.

Select examples of normal and abnormal sperm morphology
Xenzo at English Wikipedia, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0&gt;, via Wikimedia Commons 

Big-headed sperm may carry extra genetic material, whereas small-headed sperm may have reduced genetic material, or alternatively, a defect in the packet of enzymes used to help penetrate the egg. A pinheaded sperm is an extreme example of a small-headed sperm, one in which there may be no DNA content present. Taper-headed sperm have cigar-shaped heads and often have abnormal DNA or abnormal DNA packaging.  An extreme form of a taper-headed sperm is a thin, narrow-headed sperm that may harbor damaged DNA.

Round-headed sperm have globe-shaped heads that may indicate absence or damage to the packet of enzymes that facilitate sperm penetrating the egg. This may also occur if the sperm nucleus breaks down and its coiled DNA unravels and fills the sperm head. Vacuolated nuclei sperm have large bubbles (vacuoles) within the sperm head that may adversely affect fertility. Headless sperm completely lack genetic material and tailless sperms lack the wherewithal to swim the long journey from vagina to fallopian tube. Multi-headed sperm have more than one head and low fertilization potential.

Large midsection sperm may harbor defective mitochondria (the powerhouse of the cell) or a missing or defective system for moving the chromosomes stored in the midsection.

Coiled-tail sperm have tails like pigs and cannot swim effectively.  Absent-tail sperm lack the wherewithal to move to where they are needed to fertilize the egg. Short-tail sperm have defective tails that are insufficient for motility.

What Is the Cause of Abnormal Morphology?

A number of underlying factors may contribute to abnormal morphology, including testes exposure to elevated temperatures, toxin exposure, viral and bacterial infections, and genetics.

Management of Abnormal Sperm Morphology

Simple Measures to Optimize Sperm Parameters

(It’s pretty much always about a healthy lifestyle):

  • Healthy weight
  • Healthy diet with plenty of vegetables and fruits (rich in anti-oxidants)
  • Regular exercise
  • Avoid tobacco and limit alcohol
  • Avoid marijuana and anabolic steroids
  • Avoid excessive stress and learn how to manage it
  • Avoid exposure of testes to excessive heat: steam baths, saunas, hot baths, laptops, etc.

If abnormal sperm morphology adversely affects fertility and does not respond to simple measures, some couples will need to resort to assisted reproductive methods, including intra-uterine insemination (IUI), invitro fertilization (IVF), or intra-cytoplasmic sperm injection (ICSI).

Wishing you the best of health,

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Dr. Andrew Siegel is a physician and urological surgeon who is board-certified in urology as well as in female pelvic medicine and reconstructive surgery.  He is an Assistant Clinical Professor of Surgery at the Rutgers-New Jersey Medical School and is a Castle Connolly Top Doctor New York Metro AreaInside Jersey Top Doctor and Inside Jersey Top Doctor for Women’s Health. His mission is to “bridge the gap” between the public and the medical community. He is a urologist at New Jersey Urology, the largest urology practice in the United States.  He is the co-founder of PelvicRx and Private Gym.  His latest book is Prostate Cancer 20/20: A Practical Guide to Understanding Management Options for Patients and Their Families. 

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Video trailer for Prostate Cancer 20/20

Preview of Prostate Cancer 20/20

Andrew Siegel MD Amazon author page

PROSTATE CANCER 20/20 is now available at Audible, iTunes and Amazon as an audiobook read by the author (just over 6 hours). 

Dr. Siegel’s other books:

THE KEGEL FIX: Recharging Female Pelvic, Sexual, and Urinary Health

Video on THE KEGEL FIX

MALE PELVIC FITNESS: Optimizing Sexual and Urinary Health

PROMISCUOUS EATING— Understanding and Ending Our Self-Destructive Relationship with Food

FINDING YOUR OWN FOUNTAIN OF YOUTH: The Essential Guide to Maximizing Health, Wellness, Fitness and Longevity



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