Intravitelline injection of cultured rat embryos: An improved method for the identification of cytotoxic and non-cytotoxic teratogens.
A preliminary study of a novel developmental toxicity screen has been carried out. The technique involves the direct injection into the vitelline circulation of the 11.5-day rat conceptus, by-passing the metabolically active visceral yolk sac. The evaluation was performed blind using four coded model compounds: sulphanilamide (non-cytotoxic, non-teratogen), retinoic acid (teratogen) and methotrexate and cyclophosphamide (both cytotoxic teratogens). Seven parameters of teratogenicity and cytotoxicity were measured (yolk sac diameter, crown-rump length, somite number, yolk sac protein, yolk sac DNA, embryo protein, embryo DNA) and morphological abnormalities were also noted. The results showed that this technique successfully identified the developmental toxins and, moreover, differentiated between teratogens and cytotoxic teratogens. Additionally, the results show that methotrexate and cyclophosphamide produced an effect without prior exogenous activation as is necessary in other in vitro tests.
Cumberland
P F
PF
Anatomy Department, University of Leicester, PO Box 138, University Road, Leicester LE1 9HN, UK.
Richold
M
M
Parsons
J F
JF
Pratten
M K
MK