Hamster zona-free ovum test

The hamster zona-free ovum test (HZFO test), or hamster egg-penetration test, or sometimes just hamster test, is an in-vitro test used to study physiological profile of spermatozoa.[1] The primary application of the test is to diagnose male infertility caused by sperm unable to penetrate the ova. The test has limited value, due to expense and a high false negative rate.[2]

Hamster zona-free ovum test
Purposeto diagnose male infertility

Procedure

In this test, sperm are incubated with several hamster eggs. After seven to twenty hours, the number of sperm penetrations per egg is measured. The hamster eggs have had the zona pellucida, the outer membrane, removed—hence, zona-free.[3]

Having all eggs penetrated by multiple sperm is considered to be a positive sign for fertility. Results suggest that men whose sperm fail the hamster test are a third as fertile than those whose sperm pass.[4]

Although medical professionals often present the procedure as unable to create an embryo,[5] these claims are not technically correct. If the human sperm succeeds in penetrating the hamster egg, a hybrid embryo is indeed created, known as a humster.[6] These embryos are typically destroyed before they divide into two cells; were they left alone to divide, they would still be unviable.[7]

The practice is made licensable in the United Kingdom by the Human Fertilisation and Embryology Act 1990.[8]

Use

The hamster zona-free ovum test was frequently performed by sperm banks when screening potential sperm donors. It was particularly useful in assessing the extent to which sperm from a potential donor could penetrate cervical mucus when artificial insemination was principally performed by ICI or IVI, rather than by IUI. It may still be used when the sperm of a donor is intended to be used in IVF procedures because it can illustrate the ease by which the sperm can penetrate the egg. However, owing to the unreliability of these tests and the advancement of computer tests for the screening of sperm, tests by sperm banks using these methods largely fell out of favour during the 1990s.

Significance

Donated sperm and intracytoplasmic sperm injection techniques are considered more strongly for those whose sperm fail this test.

This test evaluates the acrosome reaction of human spermatozoa. However, the incidence of acrosome reaction in freely swimming human sperm does not accurately reflect the fertilizing ability of the sperm.[9][10]

This test has a poor predictive value for the success of fertilization in IVF treatment at any insemination concentration.[10] No strong correlation has been found between hamster egg penetration rates and the various semen parameters and the role of the hamster egg penetration test in the investigation of the causes of infertility should be evaluated further.[11] However, a negative result on the hamster test correlates with a lower probability of the man's partner becoming pregnant.[12]

See also

References
  1. Mortimer, David (1994). Practical laboratory andrology. New York: Oxford University Press. pp. 221–237. ISBN 9780195065954.
  2. Padubidri; Daftary (2011). Shaw's Textbook of Gynaecology, 15e. p. 204. ISBN 9788131225486
  3. Peterson, C. Matthew; Jones, Kirtly Parker; Hatasaka, Harry H.; Wong, Kenneth H. H. (October 2002). "Hamster Egg Penetration Test" (PDF). University of Utah Health Sciences Center. Utah Center for Reproductive Medicine. Archived from the original (PDF) on 22 Jan 2019. Retrieved 17 April 2013.
  4. Koulischer L, Debry JM (1989). "[The hamster test. Practical consequences]". Acta Urol Belg (in French). 57 (1): 77–81. PMID 2718849.
  5. Peterson et al. 2002: "The human sperm does not fertilize the hamster eggs."
  6. Bonnicksen, Andrea (2009). Chimeras, Hybrids, and Interspecies Research Politics and Policymaking. Georgetown University Press. p. 62. ISBN 9781589015746.
  7. Final Report of the Human Embryo Research Panel (Report). Bethesda, MD: National Institutes of Health. 27 September 1994. As cited in Bonnicksen 2009.
  8. "Human Fertilisation and Embryology Act 1990, Schedule 2, Section 1(1)(f)".
  9. Yang, YS; Rojas, FJ; Stone, SC (Dec 1988). "Acrosome reaction of human spermatozoa in zona-free hamster egg penetration test". Fertility and Sterility. 50 (6): 954–9. doi:10.1016/S0015-0282(16)60380-1. PMID 3203761.
  10. Zainul Rashid, MR; Fishel, SB; Thornton, S; Hall, JA; Ndukwe, G; Aloum, M; Fleming, SD (Mar 1998). "The predictive value of the zona-free hamster egg penetration test in relation to in-vitro fertilization at various insemination concentrations". Human Reproduction (Oxford, England). 13 (3): 624–9. doi:10.1093/humrep/13.3.624. PMID 9572423.
  11. Osser, S; Wramsby, H; Liedholm, P (May–Jun 1988). "A comparison between the hamster egg penetration test and the seminal parameters in men of infertile couples". International Journal of Fertility. 33 (3): 207–11. PMID 2899568.
  12. Koulischer L, Debry JM (1989). "The hamster test. Practical consequences". Acta Urologica Belgica (in French). 57 (1): 77–81. PMID 2718849.
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