Expression pattern of the lipocalin apolipoprotein D during mouse embryogenesis.

Apolipoprotein D (ApoD) is a secreted protein that belongs to the lipocalin family. We describe the expression pattern of ApoD during mouse embryogenesis by in situ hybridization using RNA probes. ApoD is expressed at E9 in mesenchymal cells in the rombencephalic-mesencephalic region. At E9.5 the cephalic ApoD-positive cells appear in the mesenchyme, and at later stages (starting at E10.5) ApoD expression is seen in meninges. Within the neuroepithelium, ApoD is expressed in pericytes surrounding brain and spinal cord capillaries from E10.5 to birth. Other places of expression of ApoD are the mesenchyme surrounding the olfactory epithelium and semicircular canals, as well as chondroblasts of skull and vertebrae.