This work follows from an interest in the total-dose
infusion method of administering iron to anaemic patients.
A colloidal iron dextran (ID) of mean particle size run
by 6 nm containing 200 mg Fe/ml was injected into 7-week-old healthy male rats giving single doses of 20, 60, 400
and 500 mg Fe/Kg body weight. Control rats were kept up
to 59 wk and ID-treated were killed between 10 min and 1 yr
after injection. Their livers were fixed by perfusion
through the portal veins, the most successful method being
with 1% OsO₄ in 0.17M sodium cacodylate at 0-4°C, pH 7.4
and at 8.8 mm Hg pressure.
The ultrastructure of sinusoidal lining cells is
described, and their great diversity shown. Membrane
phenomena, including micropinocytosis vermiformis, are
shown in control rats of various ages.
Particles of ID are seen in membranous vacuoles in
Kupffer cells 10 min after injection. Membrane changes
of these cells during ID uptake are micropinocytosis
vermiformis and invaginations, with both containing ID
in their lumina. Coated vesicles are seen on the
membranes, but do not appear to have any significant
role in the ID uptake.
The ID is seen in the space of Disse and is taken
up by both luminal and abluminal surfaces of lining cells.
It is concentrated in membrane-bound vacuoles, some
Use other side if necessary.
containing remains of organelles and identified as
secondary lysosomes. Acid phosphatase activity
increases in lining cells within 2 hr implying a rise
in lysosomal content, "but a noticeable increase in
primary lysosomes is not seen in electron micrographs.
This coincides with an increase in ferritin content in
the vacuoles which also contain modified ID and various
smaller electron-dense particles. The last ID is seen
at 27 wk after injection.
Within 2 hr of injection small aggregations of ID
particles are present in parenchymal cells; these
increase in size and number with time and concentrate in
the peribiliary region.
The tissue appeared healthy throughout the study,
with the only differences between control and ID-treated
being due to the high iron content in the cells.