
etiology of trypan blue induced antenatal
hydrocephalus in the albino rat
wistar strain albino rats were injected with 1 cm3 of a 1% solution
of trypan blue.  three types of dye were used: matheson, coleman and bell,
chroma-gesellschaft and a highly purified sample.  the dyes were injected on
days 6, 7, and 8 of gestation.  fetuses were excised from days 16 through 20,
fixed, decalcified where necessary, embedded in paraffin, serially sectioned
and stained.  newborn young were treated similarly.  chroma-gesellschaft
trypan blue was without reproductive or teratogenic effect at the above doses.
increasing the dose did not increase the teratogenicity but did yield a
decrease in litter size.  both matheson, coleman and bell trypan blue and the
purified sample were teratogenic.  the most frequent neural defect observed
was hydrocephalus.  serial sections of the newborn hydrocephalics showed an
occluded or extremely tenotic aqueduct of sylvius in 31 of 33 sectioned
animals.  the fetuses collected from days 18 through 20 also had occluded or
stenotic aqueducts if hydrocephalic.  aqueductal stenosis or occlusion was
present in 17-day-old fetuses, but hydrocephalus was not conclusively
demonstrated at this age.  sixteen-day-old fetuses did not have aqueductal
occlusion in any of those examined, but stenosis was evident.  it is concluded
that the defect predisposing to hydrocephalus in the young of trypan blue
treated rats of this strain is aqueductal stenosis or occlusion.
