Laboratory of Tissue Plasticity, Department of Molecular Cell Biology, University of Leuven (K.U. Leuven), Leuven, Belgium.
Stem Cells Dev. 2012 Mar 20;21(5):801-13. doi: 10.1089/scd.2011.0496. Epub 2011 Nov 16.
The rodent pituitary gland undergoes prominent maturation during the first weeks after birth, including a well-known increase in hormone-producing cells. In the past, it has frequently been postulated that stem cells are involved in this early-postnatal growth phase. This hypothesis can now be explored, as pituitary stem/progenitor cells were recently identified. Here, we analyzed in detail the mouse pituitary stem/progenitor cell compartment during the first postnatal week and compared its phenotype with that at the end of the first pituitary growth wave and at adult age. Stem/progenitor cells, as assessed by both side population phenotype and Sox2 expression, are most abundant at birth and gradually decline toward adulthood. The neonatal stem/progenitor cell compartment is clearly more active in terms of proliferation, stemness gene expression, and stem cell-related functional activity including sphere formation and multipotent differentiation capacity. In situ examination of pituitary sections reveals peculiar topographical arrangements of Sox2+ cells, again more pronounced at the neonatal age. Sox2+ cells are particularly prominent at the wedge junction of the anterior and intermediate lobe, and clusters of Sox2+ cells appear to sprout from this and other cleft-lining, marginal zone regions. Colocalization of Sox2 and hormones is generally not observed, thus suggesting mutually exclusive expression. Together, the neonatal pituitary stem/progenitor cell compartment displays an activated phenotype, thus supporting its involvement in the early-postnatal maturation process of the gland.
啮齿动物的垂体在出生后的头几周内经历显著的成熟过程，包括激素产生细胞的明显增加。过去，人们经常假设干细胞参与了这个早期的出生后生长阶段。现在可以探索这个假说，因为最近已经鉴定出垂体干细胞/祖细胞。在这里，我们详细分析了出生后第一周的小鼠垂体干细胞/祖细胞区室，并将其表型与第一个垂体生长波结束时和成年时的表型进行了比较。干细胞/祖细胞，如侧群表型和 Sox2 表达所评估的，在出生时最为丰富，并逐渐下降到成年期。与成年期相比，新生的干细胞/祖细胞区室在增殖、干性基因表达和与干细胞相关的功能活性方面更为活跃，包括球体形成和多能分化能力。对垂体切片的原位检查显示 Sox2+细胞的特殊拓扑排列，在新生儿期更为明显。Sox2+细胞在前叶和中间叶的楔形连接处特别突出，并且 Sox2+细胞簇似乎从该处和其他裂隙衬里、边缘区区域发芽。Sox2 和激素的共定位通常不观察到，因此提示它们的表达是相互排斥的。总之，新生的垂体干细胞/祖细胞区室显示出激活的表型，从而支持其参与腺体的早期出生后成熟过程。
