The Origin of a New Progenitor Stem Cell Group in Human Development.

The observation of two precursor groups of the early stem cells (Groups I and II) leads to the realization that a first amount of fetal stem cells (Group I) migrate from the AMG (Aortal-Mesonephric-Gonadal)-region into the aorta and its branching vessels. A second group (Group II) gains quite a new significance during human development. This group presents a specific developmental step which is found only in the human.

Cell death as a regulator of cerebellar histogenesis and compartmentation.

Programmed cell death is essential for the homeostasis of tissues and organs. During the development of the central nervous system, programmed cell death is highly regulated and restricted to distinct developmental time points of histogenesis. In this review, we will summarize recent data on the temporal and spatial distribution of programmed Purkinje cell death within the cerebellar cortex.

Local desynchronization of cellular development within mammalian male germ cell clones.

Mammalian male germ cells go through the process of spermatogenesis as cell clones. The members of a clone are joined by intercellular bridges which are responsible for synchronizing the spermatogenetic process. The present ultrastructural study on pubertal and adult golden hamster and mouse testes, however, demonstrates that a strict synchronization of germ cell development is not attained by this clonal association in any single instance.

Physiological purkinje cell death is spatiotemporally organized in the developing mouse cerebellum.

Physiological cell death is crucial for matching defined cellular populations within the central nervous system. Whereas the time course of developmental cell death in the central nervous system is well analyzed, information about its precise spatial patterning is scarce. Yet, the latter one is needed to appraise its contribution to circuit formation and refinement.

Alopecia and male infertility in oligotriche mutant mice are caused by a deletion on distal chromosome 9.

The recessive mutation oligotriche (olt) affects the coat and male fertility in the mouse. In homozygous (olt/olt) mutants, the coat is sparse, most notably in the inguinal and medial femoral region. In these regions, almost all hair shafts are bent and distorted in their course through the dermis and rarely penetrate the epidermis because the hair cortex is not fully keratinized.

Engrailed-2 regulates genes related to vesicle formation and transport in cerebellar Purkinje cells.

Engrailed transcription factors regulate survival, cell fate decisions and axon pathfinding in central neurons. En-2 can also attenuate Purkinje cell (PC) maturation. Here, we use array analysis to scrutinize gene expression in developing PCs overexpressing Engrailed-2 (L7En-2).

The bridge-partitioning complex is absent in a distinct type of defective germ cell division in the gonads of the golden hamster.

Intercellular bridges (IBs) connecting the cytoplasms of a defined type of defective germ cell division ("arrested mitoses") in male and female gonads of the immature golden hamster were studied by electron microscopy. In both sexes, such cells appear at the time when germ cells switch from mitotic proliferation to the onset of meiotic prophase, i.e.