Hematopoietic and Vascular System Toxicity - Zebrafish: Methods for Assessing Drug Safety and Toxicity - page 72

poiesis moves from the AGM at 36hpf to the caudal hematopoietic tissue (CHT)
(Murayama et al., 2006). By 3-4 days post fertilization (dpf), all hematopoiesis occurs
in the thymus and pronephros (kidney). Blood cells of all types develop in the kidney
in between the renal tubules, referred to as “kidneymarrow.” One exception is T cells,
which originate from the kidney but are educated in the thymus (Traver et al., 2003a).
7.2.4 Differentiated Blood Cells
Hematopoietic cell types can be differentiated based on morphological features when
cells are stained with May-Grunwald and Giemsa stains (Fig. 7.1). In addition, some
blood cell types can be identified by other staining methods described in this chapter.
Each lineage can also be characterized by specific gene expression profiles.
7.2.5 Lymphocytes
Zebrafish have both B cells and T cells that express many of the same genes as
mammalian lymphocytes (Langenau et al., 2004) and are morphologically very
similar (Fig. 7.1). Study of rag1 expression patterns demonstrates that B-cell
lymphopoiesis begins in the pancreas by 4dpf, but later occurs in the kidney (Danilova
and Steiner, 2002). T-cell progenitors, on the other hand, are first seen in the thymi at
3-4dpf as determined by expression of ikaros, lck, rag1, rag 2, and other genes
Figure 7.1 Hematopoiesis in the adult zebrafish. All blood cells are derived from a hematopoietic stem
cell. Images are cells stained with May-Grunwald and Giemsa stains (Traver et al., 2003a).