What Is Germ Cell Aplasia?

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Germ cell aplasia is a cause of infertility in people with testes. This condition is also known as Sertoli cell-only syndrome and del Castillo syndrome. People with germ cell aplasia produce few or no sperm cells and cannot impregnate their partners naturally through sexual intercourse.

The testes contain seminiferous tubules, where sperm cells develop. These sperm cells are nourished by Sertoli cells, which line the insides of the tubules. People with germ cell aplasia have Sertoli cells but no sperm cells. This is referred to as azoospermia. People with azoospermia produce no sperm or very few sperm. 

It is estimated that less than 3% to 7% of infertile males have germ cell aplasia. In this article we’ll explain the causes, diagnosis, and treatments for this condition.

Couple affected by infertility diagnosis of germ cell aplasia hold hands

fizkes / Getty Images

Germ Cell Aplasia Symptoms

Infertility is typically the only symptom of germ cell aplasia. Many people who have this condition do not exhibit any additional outward symptoms.

Some underlying causes of germ cell aplasia, such as Klinefelter's syndrome, may cause symptoms that range from mild to severe.

Klinefelter's syndrome is a genetic abnormality. People with this condition are born with one Y sex chromosome and two X sex chromosomes. Symptoms of Klinefelter's syndrome include:

  • Small testicles
  • Above-average height
  • Low testosterone levels (determined through a blood test)
  • Reduced amounts of facial and body hair
  • Decreased muscle mass
  • Decreased bone density


There are several potential causes of germ cell aplasia. In many instances, an underlying cause will not be found. Causes of germ cell aplasia include:

  • Klinefelter's syndrome
  • History of prolonged exposure to toxins
  • Severe trauma to the reproductive tract
  • History of radiation therapy


Azoospermia is usually discovered during an infertility evaluation that includes a semen analysis. A semen analysis is a diagnostic tool that checks for male factor infertility. This test analyzes the quantity and quality of sperm within an ejaculate.

To take this test, you will masturbate into a sterile container, usually in a clinic setting. If very few or no sperm are found, a second semen analysis may be done several months later to see if there is any change.

If germ cell aplasia is suspected after these tests, your healthcare provider may recommend further testing with a testicular biopsy (a sample is removed to be analyzed in the laboratory).

A testicular biopsy is an outpatient procedure done under local or general anesthesia. This test will help your healthcare provider uncover and rule out other potential diagnoses that affect sperm production, such as a tubal blockage or infection.

A testicular biopsy may also be done to extract sperm cells from the testes that can be used to fertilize an egg during fertility treatments.


There is no cure or treatment for germ cell aplasia. However, treatments exist that may help you become a parent, if that is your goal.

People with a very low sperm count may have sperm cells extracted during a testicular sperm extraction (TESE) procedure. To achieve pregnancy, TESE is done in conjunction with in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI).

During a TESE procedure, your surgeon will make a small incision in the testis and examine the tubules to check for sperm. If usable sperm are found, the sperm may be cryopreserved (frozen) for future use or used during an IVF-ICSI procedure.

Instead of TESE, your healthcare provider may recommend microdissection testicular sperm extraction (MicroTESE) to you. MicroTESE may be more effective than TESE in some people who are azoospermic. MicroTESE is done under general anesthesia using an operating microscope.

During this procedure, testicular tissue will be viewed and checked for sperm under the microscope. MicroTESE requires the removal of less testicular tissue than TESE and is considered safer and more effective for retrieving viable sperm. Sperm extracted with microTESE are used for IVF-ICSI or frozen for later use.

ICSI is a laboratory procedure that is done before IVF. During ICSI, a single sperm is injected directly into an egg that has been surgically removed from a person with ovaries (egg-producing organs). If fertilization occurs, the fertilized egg (embryo) will mature in a laboratory for one to five days.

The embryo will then be implanted during IVF into the uterus (womb) of the person who will carry the pregnancy to term.


If you have germ cell aplasia, the procedures needed to achieve pregnancy can be stressful and expensive. If you have a partner, you may both feel a range of emotions that include worry, anxiety, and depression. There is also no guarantee that these procedures will work. For all of those reasons, holding onto hope can be challenging.

Setting reasonable expectations can help. Talk to your healthcare provider about what you can expect, and the anticipated odds for success. While not a guarantee, knowing your healthcare provider's opinion can help you decide on an appropriate course of action.

Therapy, either alone or as a couple, can also help you manage your emotions and provide a roadmap that includes options for parenting. These may include living child-free, using donor sperm, adoption, or foster care adoption.


Germ cell aplasia (Sertoli cell-only syndrome) is a cause of infertility in people with testes. People with this condition are azoospermic and ejaculate very few or no sperm.

In many cases, the cause of germ cell aplasia is not known. Klinefelter’s syndrome, trauma to the reproductive system, and toxin exposure are potential causes. While not a cure, treatments exist that may help some people with this condition become parents.

A Word From Verywell

It can be upsetting to find out you have germ cell aplasia. If you have actively been attempting conception with a partner, this diagnosis can be challenging to hear. Unfortunately, the path to parenthood is not always an easy one.

Even if there are challenges along the way, you may be able to find the right course of action for you. Many people with this condition go on to form families and have happy lives.

5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Genetic and Rare Diseases Information Center (GARD). Sertoli cell-only syndrome.

  2. Ghanami Gashti N, Sadighi Gilani MA, Abbasi M. Sertoli cell-only syndrome: etiology and clinical managementJ Assist Reprod Genet. 2021;38(3):559-572. doi:10.1007/s10815-021-02063-x

  3. MedlinePlus. Klinefelter syndrome.

  4. Krzastek SC, Farhi J, Gray M, Smith RP. Impact of environmental toxin exposure on male fertility potential. Transl Androl Urol. 2020;9(6):2797-2813.

  5. American Society for Reproductive Medicine. What is intracytoplasmic sperm injection (ICSI)?

By Corey Whelan
Corey Whelan is a freelance writer specializing in health and wellness conntent.