Abstract
The anterior and intermediate lobes of the pituitary gland develop through invagination of the oral ectoderm and as they are endocrine tissues, they participate in the maintenance of vital functions via the synthesis and secretion of numerous hormones. We recently observed that several extrapituitary cells invade the anterior lobe of the developing pituitary gland. This raised the question of the origin(s) of these S100β-positive cells, which are not classic endocrine cells but instead comprise a heterogeneous cell population with plural roles, especially as stem/progenitor cells. To better understand the roles of these S100β-positive cells, we performed immunohistochemical analysis using several markers in S100β/GFP-TG rats, which express GFP in S100β-expressing cells under control of the S100β promoter. GFP-positive cells were present as mesenchymal cells surrounding the developing pituitary gland and at Atwell's recess but were not present in the anterior lobe on embryonic day 15.5. These cells were negative for SOX2, a pituitary stem/progenitor marker, and PRRX1, a mesenchyme and pituitary stem/progenitor marker. However, three days later, GFP-positive and PRRX1-positive (but SOX2-negative) cells were observed in the parenchyma of the anterior lobe. Furthermore, some GFP-positive cells were positive for vimentin, p75, isolectin B4, DESMIN, and Ki67. These data suggest that S100β-positive cells of extrapituitary origin invade the anterior lobe, undergoing proliferation and diverse transformation during pituitary organogenesis.
Highlights
The adenohypophysis, which is composed of anterior and intermediate lobes, develops through invagination of the oral ectoderm under the influence of several growth factors by contactingPLOS ONE | DOI:10.1371/journal.pone.0163981 October 3, 2016S100β+ Mesenchymal Cells in Embryonic Pituitary the diencephalon and both sides of the ectoderm [1,2,3]
The recess is characterized as an intraglandular fossa that receives several blood vessels [16]; we have previously suggested that PRRX1-positive cells are present here and invade in order to participate in pituitary vasculogenesis [18,19]
We performed triple immunostaining for green fluorescent protein (GFP), PRRX1, and SOX2
Summary
S100β+ Mesenchymal Cells in Embryonic Pituitary the diencephalon and both sides of the ectoderm [1,2,3]. Both the anterior and intermediate lobes contain six types of differentiated cells that play important roles in the synthesis and secretion of several hormones. These endocrine cells are required in all vertebrates for the maintenance of vital functions such as reproduction, metabolism, growth, and homeostasis. Substantial populations of non-hormone-producing cells exist in the anterior and intermediate lobes and participate in maintaining, assisting, and supplementing hormone-producing cells and the vessel system. S100β-positive cells in the anterior lobe are believed to have several roles, acting as stem cells, phagocytes, cells that regulate hormone release, and cells that participate in cell-cell communication [5,6,7]
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