Ontogenèse des cellules germinales primordiales

Abstract

Chez les animaux à reproduction sexuée, les gamètes proviennent d’une petite population cellulaire apparaissant très tôt au cours du développement embryonnaire, les cellules germinales primordiales (PGC). Ces cellules représentent une population cellulaire clé responsable de la survie et de l’évolution des espèces. En effet, la production de gamètes permet la fécondation et donc l’établissement de la génération suivante. Chez les mammifères, l’étude des PGC est restée, jusqu’à peu, très confidentielle. Elles ont récemment acquis un nouvel intérêt dans la mesure où il est possible d’en dériver des cellules pluripotentes, les cellules germinales embryonnaires (EGC), dont les caractéristiques sont très proches de celles des cellules souches embryonnaires (ESC).

In sexually reproducing animals all gametes of either sex arise from primordial germ cells (PGC). PGC represent a small cell population, appearing early during embryo development. They represent a key cell population responsible for the survival and the evolution of a species. Indeed, the production of gametes will assure fertilisation and therefore the establishment of the next generation. Until recently only few laboratories were working on PGC biology. A new interest emerged since these cells have the ability to function as pluripotent stem cells when established as cell lines. Indeed, like embryonic stem cells (ESC), embryonic germ cells (EGC) are able to differentiate in a wide variety of tissues. In vivo, EGC are able, after injection into a host blastocyst cavity to colonise the inner cell mass and to participate in embryonic development. In vitro studies in human and mouse have also shown their capacity to differentiate into a large variety of cell types allowing the study of processes involved in cardiomyocyte, haematopoietic, neuronal and myogenic differentiation pathways. We present here the last updates of PGC ontogeny focusing mainly on the murine model.