This book presents the current state of knowledge on the origin and differentiation of cell lines involved in the development of the vertebrate male and female gonads with particular emphasis on the mouse. It also discusses the processes leading to the testis- and ovary-specific structures and functions. The individual chapters review the origin and differentiation of the somatic cells of the genital ridges; the formation and migration of primordial germ cells in mouse and man; the gonadal supporting cell lineage and mammalian sex determination; differentiation of Sertoli and granulosa cells; mesonephric cell migration into the gonads and vascularization; origin and differentiation of androgen-producing cells in the gonads; germ cell commitment to the oogenic versus spermatogenic pathway and the role of retinoic acid; ovarian folliculogenesis; control of oocyte growth and development by intercellular communication within the follicular niche; biology of the Sertoli cell in the fetal, pubertal and adult mammalian testis; mechanisms regulating spermatogonial differentiation; stem cells in mammalian gonads; the role of microRNAs in cell differentiation during gonad development; human sex development and its disorders; as well as methods for the study of gonadal development.

One of the oldest problems in developmental biology is the differentiation between germ line and somatic cells. The continuity of germ line cells between subsequent generations of multicellular organisms was first suggested by Owen, and later elaborated by A. Weismann to his famous germ line theory. His additional assumption that cellular differentiation was based on a differential representation of the genetic material in somatic cells was soon disproved. In some, apparently exceptional, cases, however, such differences in the genetic material between germ line and somatic cells were discovered. The best-known example is the nematod Ascaris. Boveri discovered and studied the fundamental differences in the karyotypes of germ line and soma of Parascaris equorum. Later, similar situations were found in some other organisms. However, in particular the work ofSpemann demonstrated that cellular differentiation in general is not accompanied by fundamental changes of the genetic material. Subsequently, the relatively few examples of germ line-soma differences achieved by chromatin elimination processes have been considered as a curiosity. Experimental studies have been essentially restricted to Ascaris species and to the pioneering cytological studies of chromatin elimination by S. Beermann. Despite the large proportions of the genome involved in chromatin elimina tion, our knowledge of this process is still very restricted. In particular the biological meaning of this differentiation process is entirely obscure. In this context one must, however, consider that also for the majority of DNA sequences in eukaryotic genomes the biological relevance is unclear.

Recent scientific breakthroughs, celebrity patient advocates, and conflicting religious beliefs have come together to bring the state of stem cell researchâ€"specifically embryonic stem cell researchâ€"into the political crosshairs. President Bush's watershed policy statement allows federal funding for embryonic stem cell research but only on a limited number of stem cell lines. Millions of Americans could be affected by the continuing political debate among policymakers and the public. Stem Cells and the Future of Regenerative Medicine provides a deeper exploration of the biological, ethical, and funding questions prompted by the therapeutic potential of undifferentiated human cells. In terms accessible to lay readers, the book summarizes what we know about adult and embryonic stem cells and discusses how to go about the transition from mouse studies to research that has therapeutic implications for people. Perhaps most important, Stem Cells and the Future of Regenerative Medicine also provides an overview of the moral and ethical problems that arise from the use of embryonic stem cells. This timely book compares the impact of public and private research funding and discusses approaches to appropriate research oversight. Based on the insights of leading scientists, ethicists, and other authorities, the book offers authoritative recommendations regarding the use of existing stem cell lines versus new lines in research, the important role of the federal government in this field of research, and other fundamental issues.

1 Kevin Moses It is now 25 years since the study of the development of the compound eye in Drosophila really began with a classic paper (Ready et al. 1976). In 1864, August Weismann published a monograph on the development of Diptera and included some beautiful drawings of the developing imaginal discs (Weismann 1864). One of these is the first description of the third instar eye disc in which Weismann drew a vertical line separating a posterior domain that included a regular pattern of clustered cells from an anterior domain without such a pattern. Weismann suggested that these clusters were the precursors of the adult ommatidia and that the line marks the anterior edge of the eye. In his first suggestion he was absolutely correct - in his second he was wrong. The vertical line shown was not the anterior edge of the eye, but the anterior edge of a moving wave of patterning and cell type specification that 112 years later (1976) Ready, Hansen and Benzer would name the "morphogenetic furrow". While it is too late to hear from August Weismann, it is a particular pleasure to be able to include a chapter in this Volume from the first author of that 1976 paper: Don Ready! These past 25 years have seen an astonishing explosion in the study of the fly eye (see Fig.

The relationship of cell lineage and differentiation is one of the most intriguing problems in developmental biology. In most higher organisms, the analysis of the cell lineage has to rely on indirect methods. Only in the most suitable systems, like the nematodes, can the pattern of cell division be determined by direct observation under the microscope. In cases where this is not possible, the fate of the cells has to be examined by using cell markers. Most suitable for this purpose are genetic markers, provided that they do not interfere with the developmental pathway to be studied. However, suitable genetic markers and techniques for generating genetic mosaics are available in a few organisms only. Therefore, this volume is largely concerned with Drosophila and the mouse, which have been studied most extensively. In 1929 STURTEVANT introduced the analysis of gynandromorphs into devel opmental genetics. However, this important contribution remained largely unnoticed until the late sixties, when the potential of this technique for deter mining embryonic fate maps and the number of primordial cells was exploited, and the methodology extended to the mapping of mutational foci. Mitotic recombination was demostrated by STER:-

This book presents an overview of various aspects of chromosome research, written by leading experts of the respective fields, combining classic and recent molecular biological results. The variety and comprehensiveness make it a handbook of chromosome research for all scientists, teachers and graduate students interested in this field. Dieses Buch faßt die unterschiedlichen Aspekte der Chromosomenforschung in Beiträgen von führenden Wissenschaftlern zusammen, wobei die klassischen Erkenntnisse mit neuesten Forschungsdaten zu einem umfassenden Überblick über das Gebiet kombiniert werden.