Signals for death and survival: A two-step mechanism for cavitation in the vertebrate embryo

Abstract

Conversion of a solid primordium to a hollow tube of cells is a morphogenetic process used frequently during vertebrate embryogenesis. In the early mouse embryo, this process of cavitation transforms the solid embryonic ectoderm into a columnar epithelium surrounding a cavity. Using both established cell lines and normal embryos, we provide evidence that cavitation in the early mouse embryo is the result of the interplay of two signals, one from an outer layer of endoderm cells that acts over short distances to create a cavity by inducing apoptosis of the inner ectodermal cells, and the other a rescue signal mediated by contact with the basement membrane that is required for the survival of the columnar cells that line the cavity. This simple model provides a paradigm for investigating tube morphogenesis in diverse developmental settings.

Mammary-derived signals activate programmed cell death during the first stage of mammary gland involution

“…The interplay between death and survival factors in the mammary gland is reminiscent of their role during embryonic development. Cavitation in the vertebrate embryo occurs by inducing PCD of inner ectodermal cells through a presumed short-range signal; the columnar cells that line the cavity are simultaneously rescued by interactions with basement membrane (18). Our model of the first stage of involution shares similarities with this period of vertebrate development.…”

Establishment of new murine embryonic stem cell lines for the generation of mouse models of human genetic diseases

“…An important feature of ES cells is their ability to be induced to enter a program of differentiation in vitro. When transferred to a suspension culture, they spontaneously form aggregates of differentiating cells known as embryoid bodies (EBs) (3,(7)(8)(9)(10)(11)(12). Within the EBs, a variety of early embryonic lineages (hematopoietic, neuronal, vascular endothelial, cardiac and skeletal muscle) can be identified by morphological, immunohistochemical and RT-PCR analysis (3,6,(12)(13)(14)(15)(16).…”

D’Arcy Thompson aurait-il prédit un contrôle topologique de l’apoptose ?

“…Ainsi, il serait judicieux, à la lumière de ces nouvelles perspectives, de réévaluer expérimentalement quelques exemples bien connus d'apoptose massive et coordonnée observés au cours du développement embryonnaire, par exemple le phénomène de cavitation chez les mammifères [16] ou d'interdigitation chez les vertébrés. En effet, au moment de la maturation de l'extrémité des membres chez les vertébrés, une mort cellulaire programmée massive des cellules interdigitales se met en place, à l'origine de la forme finale des doigts ou des pattes (Figure 4).…”