Introduction: Pituitary cells positive for S100 protein are non-hormone-producing cells and are composed of heterogeneous populations, including folliculo-stellate cell. They are argued for having various functions and are detectable only after birth, but their origin is not yet clarified. Recently, we had detected S100βmRNA in the cDNA library of embryonic pituitary by real-time PCR and observed invasion of non-hormone-producing cells from surrounding mesenchyme into the anterior lobe participating in pituitary vasculogenesis. These data indicate that a possibility of invasion of extra-pituitary precursor of S100-positive cells. This study aimed to verify whether S100-positive cells exist during embryonic period by using the transgenic rat expressing GFP driven by S100β-promoter (S100β-TG).
Materials and methods: S100-TG rat embryonic pituitaries at E15.5 to E20.5 were subjected to immunohistochemistry with various antibodies.
Results and discussion: Immunohistochemistry of the embryonic pituitary at E15.5 demonstrated that GFP-positive cells existed in the mesenchymal cells surrounding the pituitary and at the Atwells recess, the intraglandular fossa. Thereafter, they were observed in the parenchyma of the anterior lobe on E18.5. Immunohistochemistry for GFP, PRRX1 (mesenchyme/pituitary-progenitor cell marker) and SOX2 (stem/progenitor cell marker) showed that GFP-positive cells were negative for PRRX1 and SOX2 in the Atwells recess on E15.5, followed by conversion to PRRX1-positive/SOX2-negative cells. Further immunostaining with other markers suggested that GFP-positive cells have characters of mesenchymal-, neural crest- and/or vascular-cells. These data indicated that some of S100-positive cells in the pituitary gland are originated from the extra-pituitary cells during embryonic period.
02 - 04 Sep 2014
World Congress of Reproductive Biology