Dawood K A, Briscoe C V, Thomas D B, Riches A C
Department of Biology and Preclinical Medicine, University of St. Andrews, Scotland.
J Anat. 1990 Feb;168:209-16.
Haematopoietic stem cells in murine fetal liver are in a proliferative state unlike those in normal bone marrow which are quiescent. A regulatory activity is produced by cells in the fetal liver which will switch quiescent normal bone marrow haematopoietic stem cells into cell cycle in vitro. This regulator from Day 15 fetal liver cells is produced by adherent cells and by cells fractionated on a Percoll gradient in the 1.064 and 1.076 g per cm3 density bands but not in the 1.123 g per cm3 band. Colony-stimulating factor cannot be detected in the supernatants containing the stem cell regulatory activity. The stimulator can be detected in supernatants produced from cell suspensions of liver cells at Day 15 and Day 17 of gestation and 24 hours and 72 hours after birth. However by 1 week after birth the production of the stimulator decreases and is undetectable 3 and 10 weeks after birth. The total numbers of haematopoietic stem cells (CFU-S) in fetal liver decrease from Day 15 of gestation and only small numbers are present 1 week after birth. Thus the decline in the production of haematopoietic stem cell proliferation stimulator correlates with the decrease in haematopoietic stem cell numbers in the liver through gestation and after birth.
与处于静止状态的正常骨髓造血干细胞不同，小鼠胎肝中的造血干细胞处于增殖状态。胎肝中的细胞会产生一种调节活性，这种活性在体外可使静止的正常骨髓造血干细胞进入细胞周期。来自妊娠第15天胎肝细胞的这种调节因子由贴壁细胞以及在Percoll梯度中密度为1.064和1.076克/立方厘米条带中分离得到的细胞产生，但在密度为1.123克/立方厘米的条带中未检测到。在含有干细胞调节活性的上清液中未检测到集落刺激因子。在妊娠第15天和第17天以及出生后24小时和72小时的肝细胞悬浮液产生的上清液中可检测到刺激因子。然而，出生后1周，刺激因子的产生减少，出生后3周和10周时无法检测到。从妊娠第15天起，胎肝中造血干细胞（CFU-S）的总数减少，出生后1周时仅存在少量造血干细胞。因此，造血干细胞增殖刺激因子产生的下降与整个妊娠期及出生后肝脏中造血干细胞数量的减少相关。
