Teratogenic effect of hydrosalpinx fluid in humans? A reply to Ng and Ajonuma

Louis Chan

Department of Obstetrics and Gynaecology,The Chinese University of Hong Kong,Prince of Wales Hospital,Shatin, SAR Hong Kong. E-mail: Lyschan{at}cuhk.edu.hk

Dear Sir,

We thank Ng and Ajonuma for their interest in our article. Whole embryo culture is a well-recognized screening tool for teratogenic studies (Steele, 1991Go). The advantage of this model is that the direct effect of the interested agent on embryogenesis can be evaluated. It is very difficult ethically, if possible, to study the teratogenic effects of hydrosalpinx fluid in vivo. The model that we employed studies embryogenesis from day 9.5 to 11.5, not because it is half the gestation of the rat’s pregnancy, but because it represents the critical period of organogenesis. This period in the rat’s pregnancy corresponded to week 3 to 4 of human development (Sadler and Warner, 1984Go). Important organs formed during this period include branchial arches, upper and lower limb buds, optic and otic vesicles, and neural tubes. Somite number reaches 33 by the end of fourth week (Moore, 1988Go). Hence this represents the best time-period for teratogenic studies.

During explantation of rat embryos, the Reichart membranes are ruptured artificially. Unlike human embryos, these rat embryos are located inside the yolk sac, which completely separate these embryos from the environment. Although human embryos are surrounded by amniotic and chorionic membranes, the toxic substance(s) in hydrosalpinx fluid may reach the embryo by simple diffusion. Because the toxic substance(s) has not been identified, it is not possible to determine the degree of trans-membrane passage of this substance. One should note that even a hydrosalpinx fluid concentration as low as 0.3% could be embryotoxic (Sachdev et al., 1997Go). Therefore a low concentration of hydrosalpinx fluid may be also teratogenic.

We fully agree that results from in-vitro experiments or animal studies do not equate to the situation in humans. But whole embryo culture does serve as a useful screening tool for teratogenic studies. Our findings suggest that further investigation and monitoring of teratogenic effects of hydrosalpinx fluid is warranted.

References

Moore, K.L. (1988) The Developing Human, 4th edn, W.B.Saunders, Philadelphia.

Sadler, T.W. and Warner, C.W. (1984) Use of whole embryo culture for evaluating toxicity and teratogenicity. Pharmacol. Rev., 36, 145S–150S.[Medline]

Sachdev, R., Kemmann, E., Bohrer, M.K. and el-Danasouri, I. (1997) Detrimental effect of hydrosalpinx fluid on the development and blastulation of mouse embryos in vitro. Fertil. Steril., 68, 531–533.[CrossRef][ISI][Medline]

Steele, C.E. (1991) Whole embryo culture and teratogenesis. Hum. Reprod., 6, 144–147.[Abstract]





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