Dr. Shamley et al., TROPHOBLASTIC GIANT-CELLS OF THE MOUSE PLACENTA CONTAIN CALBINDIN-D-9K BUT NOT THE VITAMIN-D-RECEPTOR, Journal of Endocrinology, 150(1), 1996, pp. 25-32
The effects of vitamin D deficiency on the ontogeny of calcium-binding
proteins (CaBPs) and the vitamin D receptor (VDR) in the placenta and
yolk sac of the mouse were examined. Maternal vitamin D status did no
t affect the time of appearance of CaBP-D-9k (9 kDa) in the yolk sac e
ndoderm or trophoblastic giant cells (TGCs) of the placenta. VDRs were
undetectable in TGCs and yolk sac endoderm, but were present in the i
ntraplacental yolk sac. Since yolk sac endoderm and TGCs contain CaBP
but not VDR, it is unlikely that CaBP synthesis and/or activity in the
se cells is controlled by vitamin D. The TGCs, therefore, may be invol
ved in vitamin D-independent transplacental transfer of calcium.