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We describe two complementary methods for the study of early thymus organogenesis in the mouse. The first is an in vitro technique for lineage analysis, where a chosen population of cells within the mouse embryo is labeled with a fluorescent cell tracker dye. The embryos are then transferred to who ...

All mature blood cells are derived from hematopoietic progenitors that have been defined by their ability to generate colonies of cells in semisolid media. Investigation of the cellular components of these colonies has confirmed the existence of unilineage, bilineage, and multilin ...

The progress of the last few years in the understanding of hematopoietic cell development during embryogenesis resulted from a combination of experimental approaches used in hematology and developmental biology. This methodology has been particularly powerful for the analys ...

Hematopoietic stem cells (HSCs) constitute a pool of very rare cells able to self-renew, proliferate, and/or differentiate to all the blood cell lineages during the life span. The first murine adult transplantable HSCs appear in the intraembryonic aorta-gonad-mesonephros region at em ...

In vertebrates, the earliest differentiated cell types (hematopoietic and endothelial) arise from mesoderm induced during the process of gastrulation. These cells become organized into the blood islands of the extraembryonic yolk sac and are morphologically apparent by around d 7 ...

In vivo experimental approaches that have been designed to study the ontogeny of the hematopoietic system in higher vertebrates are described in the present chapter. The avian embryo is directly available to manipulations in ovo during gastrulation and organogenesis. This permissi ...

Because zebrafish embryos are transparent, cell behaviors and interactions can be directly imaged noninvasely in live embryos using differential interference contrast-Nomarski light microscopy. We found that the imaging quality can be much improved by coupling differenti ...

The zebrafish (Danio rerio) has emerged as a powerful vertebrate genetic and developmental model that is particularly amenable to the study of hematopoiesis. The zebrafish embryo develops externally and its optical clarity allows the number and morphology of circulating blood cells ...

Xenopus embryos provide a model for studying the earliest stages in the development of the vertebrate hematopoietic system. This chapter provides detailed procedures describing the production of hematopoietic chimeras in Xenopus embryos and the analysis of these chimeras using ...

In this chapter, the procedures for specific detection of ontogenic emerging antigens during animal development are described. Anuran metamorphosis has provided us with a good experimental model for investigation of the mechanisms of tissue remodeling. The establishment of a syn ...

The primary sites of hematopoiesis change during murine ontogeny. The first blood cells emerge in two waves in the yolk sac; primitive erythroblasts, megakaryocytes, and macrophages emerge on embryonic d (E) 7.0, whereas definitive progenitor cells appear as clusters within the yolk sac v ...

In utero hematopoietic stem cell transplantation is an entirely nonmyeloablative approach to achieve mixed hematopoietic chimerism and associated donor-specific tolerance. This chapter provides the rationale and methodologic detail for the administration of stem cells ...

More than 30 yr ago, a collection of cells isolated from the bone marrow were first demonstrated to repopulate hematopoiesis in a radioablated animal. These cells self-renewed while producing all of the blood products and were named hematopoietic stem cells (HSCs). Since then, HSCs have been a tr ...

Extensive genetically determined quantitative variation exists in the number and function of hematopoietic stem cells in inbred mouse strains. Furthermore, aging of hematopoietic stem cells is genetically determined. Gene identification of quantitative trait loci invol ...

Embryonic stem (ES) cells serve as a potentially unlimited source of cells and tissues to treat a number of genetic and malignant diseases. The differentiation of these cells into specific cell types is an area of very active investigation. One method of manipulating ES cell differentiation is ...

The generation of gene-targeted and transgenic mouse models facilitates the in vivo study of mammalian gene function. Advances in technologies to engineer the mouse genome have extended the choice of gene manipulation from straightforward gene inactivation or overexpression to d ...

Today's clinical practice relies on the application of well-designed clinical research, the gold standard test of an intervention being the randomized controlled trial. Principles of the randomized controlled trial include emphasis on the principal research question, random ...

Statistical models are used to study the relationship between exposure and disease while accounting for the potential role of other factors' impact on outcomes. This adjustment is useful to obtain unbiased estimates of true effects or to predict future outcomes. Statistical models inc ...

Longitudinal and observational study designs are important methodologies to investigate potential associations that may not be amenable to RCTs. In many cases, they may be performed using existing data and are often cost-effective ways of addressing important questions. The major d ...

Clinical epidemiology is the science of human disease investigation with a focus on diagnosis, prognosis, and treatment. The generation of a reasonable question requires the definition of patients, interventions, controls, and outcomes. The goal of research design is to minimize err ...