title: Zinc is a possible toxic contaminant of silicone oil in microdrop cultures of preimplantation mouse embryos.
abstract: A batch of silicone oil (dimethylpolysiloxane) is described which had differential effects on the development of 1- and 2-cell preimplantation mouse embryos in vitro when used as a microdrop overlay over two culture media: CZB and KSOM. A high rate of development into blastocysts was observed when using CZB medium; in contrast, development was strongly inhibited when KSOM was used. Other batches of silicone oil or paraffin oil permitted development from the zygote to the blastocyst of an outbred strain of mouse without arrest at the 2-cell stage. Our results show that the higher concentrations of ethylenediaminetetraacetic acid (EDTA) and bovine serum albumin (BSA) in CZB medium, in comparison with KSOM, protect against the toxic component in the oil. Observations also gave circumstantial evidence that the toxic component in the oil is zinc. The beneficial effect of including EDTA in a medium is usually attributed to its chelating toxic metals introduced as impurities in other components of the medium. Our results now show that EDTA also protects against impurities in the oil overlay.
authors.affiliation: Laboratory of Human Reproduction and Reproductive Biology, Harvard Medical School, USA.
authors.forename: G T
authors.initials: GT
authors.lastname: Erbach
authors.forename: P
authors.initials: P
authors.lastname: Bhatnagar
authors.forename: J M
authors.initials: JM
authors.lastname: Baltz
authors.forename: J D
authors.initials: JD
authors.lastname: Biggers
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000187:drug effects*; D002417:Cattle; D002614:Chelating Agents; D003470:Culture Media / Q000633:toxicity*; D046508:Culture Techniques; D004340:Drug Contamination; D004492:Edetic Acid; D005314:Embryonic and Fetal Development / Q000187:drug effects; D005260:Female; D008297:Male; D051379:Mice; D012710:Serum Albumin, Bovine; D012827:Silicone Oils / Q000633:toxicity*; D015032:Zinc / Q000633:toxicity*
chemical_list: D002614:Chelating Agents; D003470:Culture Media; D012827:Silicone Oils; D012710:Serum Albumin, Bovine; D004492:Edetic Acid; D015032:Zinc