Maurizio Zuccotti, Carlo Alberto Redi and Silvia Garagna
Parma and Pavia
The sequence of papers starts with an interview of David Albertini and his extraordinary contribution to the knowledge of ‘the most wondrous of cells - the oocyte’ and follows with a road map of the life of an oocyte from its origin as a primordial germ cell (PGC) to completion of maturation, evidencing the hurdles encountered during this troubled journey. The female gamete is followed during its migration as a PGC towards the gonadal ridge (Mamsen et al.) and during its entry into meiosis (Spiller et al.), when, for the first time, we are able to read a whole genome transcriptional portrait of precious human PGCs in a comparative analysis with that of the mouse (Diedrichs et al.). Then, its growing phase in the adult ovary is described all through to the antral compartment, with a specific focus on metabolic changes (Collado-Fernandez et al.), the role of the Akt signalling pathway (Cecconi et al.) and the developmental relationship occurring between the oocyte and its companion theca, granulosa and cumulus cells within the antral follicle (Hennet and Combelles). During these stages of maturation, the oocyte acquires the zona pellucida, a glycoprotein layer crucial at the time of fertilisation, but, we learn here, also important for the growth of a healthy oocyte (Wassarman and Litscher). The long perdurance of the oocyte within the human ovary, maternal age, hormonal stimulation, disturbed metabolism, and depletion of the follicle pool contribute to mitochondrial dysfunction, spindle aberrations, and errors in chromosome segregation (Eichenlaub-Ritter)...