The effects of RLX on the microvasculature
of the mouse mammary gland are reported. RLX (pure
porcine standard NIH-RXN-P1) at a dose of 3 GPU was
administered subcutaneously to virgin adult mice
ovariectomized 12 days before.
The mammary glands were removed 18-20 h after
RLX injection and their examination by light microscopy
did not reveal any substantial growth-response to the
hormone .
Histology and morphometry indicated striking
dilation of microvessels, especially capillaries. and
electron microscopy revealed an increase in the
micropinocytotic vesicles, thus suggesting enhanced
transendothelial transport of substances.
Such phenomena, which were independent of
a release of granules by mast cells, may represent
an important component of the mammotrophic action
of RLX.