Liver as an extramedullary site of hematopoiesis in old GATA-1^low mice.

(A) Hematoxylin-eosin staining of liver sections from a 15-day postcoitum GATA-1^low fetus (left panel) or from adult GATA-1^low mice at 12 (middle panel) or 18 (right panel) months of age. The inset in the left panel presents CD45 immunohistochemical staining of the liver section immediately following that stained with hematoxylin-eosin. MK are indicated by solid arrowheads and solid nests of hemopoietic cells are indicated by solid arrows. Six mice were independently analyzed in the 12- to 18-month-old age group (original magnification, × 20 for the left panel, × 10 for the middle and right panels, and × 40 for the inset). (B) Frequency of hemopoietic colonies (BFU-E, CFU-E, CFU-GM, and CFU-Mk, as indicated) per 10⁵ liver cells from GATA-1^lowmice. Animals were arbitrarily divided into the same age groups used in Table 2. Results are presented as the mean (± SD) of 3 independent experiments for a total of at least 4 mice analyzed per experimental group.