Certain forms of morphological anomalies of spermatozoa may reflect chromosomal aneuploidies

Kayhan Yakin,1 and Semra Kahraman

Istanbul Memorial Hospital, Reproductive Endocrinology and ART Unit, Piyalepasa Cad.-Okmeydani, Istanbul, Turkey

Dear Sir,

We have read the paper by Viville et al. with great interest (Viville et al.2000Go). As mentioned by the authors, we have experienced poor fertilization and pregnancy rates with inevitable use of megalo-pinhead spermatozoa in intracytoplasmic sperm injection (ICSI) (Kahraman et al.1999Go). We have recently performed multicolour fluorescence in-situ hybridization (FISH) analyses with five DNA probes for simultaneous detection of chromosomes X, Y, 13, 18 and 21 in embryos developed from megalo-pinhead spermatozoa. Out of 35 embryos analysed from seven cases, 21 (60%) revealed chromosomal abnormalities (Figure 1Go). The majority of the chromosomally-abnormal embryos had aneuploidy (62%). Other abnormalities were triploidy (19%), haploidy (9.5%) and complex aneuploidy (9.5%). The high rate of aneuploidy in embryos developed from this particular form of spermatozoa was striking.



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Figure 1. The distribution of chromosomally-abnormal embryos developed from megalo-pinhead spermatozoa.

 
Controversy exists about whether morphological defects play a role in the fertilization or embryo development (Nagy et al.1995Go; Int Veld et al.1997Go; Vegetti et al.2000Go). The incidence of structural chromosomal aberrations were reported to be four times higher in spermatozoa with amorphous, round and elongated heads (Lee et al.1996Go). In animal models, it has been reported that abnormal karyotypes were significantly higher in oocytes injected with severely amorphous sperm heads (Kishikawa et al.1999Go). Some rarely seen morphological head abnormalities may be associated with anomalies in the nuclear constitution. A 60% chromosomal abnormality rate was found in embryos developed from megalo-pinhead sperm samples. In these samples, a high number of sperm heads without tails and abundant round spermatid forms were commonly observed. Round-headed spermatozoa were seldomly accompanied by these severly abnormal spermatozoa. The chromosomal abnormality rate was much higher than was expected in aneuploidy screening (Kahraman et al.2000Go). Although the number of cases was too limited to draw a conclusion, use of megalo-pinhead spermatozoa in ICSI may pose genetic risks in the developing conceptus and their use is an indication for pre implantation genetic diagnosis. Therefore, couples should be counselled about low rates of fertilization and pregnancy with ICSI when only megalo-pinhead forms are present in the ejaculate.

Notes

1 To whom correspondence should be addressed. E-mail: kyakin{at}hotmail.com Back

References

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Kahraman, S., Akarsu, C., Cengiz, G. et al. (1999) Fertility of ejaculated and testicular megalohead spermatozoa with intracytoplasmic sperm injection. Hum. Reprod., 14, 726–730.[Abstract/Free Full Text]

Kahraman, S., Bahçe, M., Samli H. et al. (2000) Healthy births and on-going pregnancies obtained by preimplantation genetic diagnosis in patients with advanced maternal age and recurrent implantation failure. Hum. Reprod., 15, 2003–2007.[Abstract/Free Full Text]

Kishikawa, H., Tateno, H. and Yanagimachi, R. (1999) Chromosome analysis of BALB/c mouse spermatozoa with normal and abnormal head morphology. Biol. Reprod., 61, 809–812.[Abstract/Free Full Text]

Lee, J.D., Kamiguchi, Y. and Yanagimachi, R. (1996) Analysis of chromosome constitution of human spermatozoa with normal and aberrant head morphologies after injection into mouse oocytes. Hum. Reprod., 11, 1942–1946.[Abstract]

Nagy, Z.P., Liu, J., Joris, H. et al. (1995) The result of intracytoplasmic sperm injection is not related to any of the three basic sperm parameters. Hum. Reprod., 10, 1123–1129.[Abstract]

Vegetti, W., Van Assche, E., Frias, A. et al. (2000) Correlation between sperm parameters and sperm aneuploidy rates investigated by fluorescence in-situ hybridization in infertile men. Hum. Reprod., 15, 351–365.[Abstract/Free Full Text]

Viville, S., Mollard, R., Bach, M.L. et al. (2000) Do morphological anomalies reflect chromosomal aneuploidies? Hum. Reprod., 15, 2563–2566.[Abstract/Free Full Text]