Tracing the emergence of primordial germ cells from bilaminar disc rabbit embryos and pluripotent stem cells.

Toshihiro Kobayashi,Aracely Castillo-Venzor,Naoaki Mizuno,Masao Hirao,Walfred W.C Tang,M Azim Surani,Yasuyuki Osada,Masumi Hirabayashi,Hiromitsu Nakauchi,Hideyuki Sato,Michael Morgan,Fumika Yoshida,Chris A Penfold

doi:10.1016/j.celrep.2021.109812

Abstract

Rabbit embryos develop as bilaminar discs at gastrulation as in humans and most other mammals, whereas rodents develop as egg cylinders. Primordial germ cells (PGCs) appear to originate during gastrulation according to many systematic studies on mammalian embryos. Here, we show that rabbit PGC (rbPGC) specification occurs at the posterior epiblast at the onset of gastrulation. Using newly derived rabbit pluripotent stem cells, we show robust and rapid induction of rbPGC-like cells invitro with WNT and BMP morphogens, which reveals SOX17 as the critical regulator of rbPGC fate as in several non-rodent mammals. We posit that development as a bilaminar disc is a crucial determinant of the PGC regulators, regardless of the highly diverse development of extraembryonic tissues, including the amnion. We propose that investigations on rabbits with short gestation, large litters, and where gastrulation precedes implantation can contribute significantly to advances in early mammalian development.

Highlights

Germline is a unique lineage that transmits genetic and heritable epigenetic imprints that confer functional differences on the parental genomes in mammals
Recent studies have highlighted the differences in the mechanism of primordial germ cells (PGCs) specification in embryos that develop as egg cylinders as in rodents, and those that develop as bilaminar discs as in humans and non-human primates (Kobayashi and Surani, 2018)
Development of bilaminar disc rabbit embryos First, we examined development of the rabbit epiblast by wholemount immunofluorescent staining (IF) in the early embryos

Summary

Introduction

Germline is a unique lineage that transmits genetic and heritable epigenetic imprints that confer functional differences on the parental genomes in mammals. Specification of primordial germ cells (PGCs), the precursors of sperm and eggs, is among the first crucial branchpoints where the pluripotent epiblast cells are subject to germline versus soma cell-fate decision (McLaren, 1981). Investigation of this fundamental cell-fate decision is of inherent interest and a paradigm for cell-state transitions that occur during development as epiblast cells start to exit from the pluripotent state. Studies on early non-human primate embryos and representative in vitro culture models provide a glimpse of primate PGC specification, including the spatiotemporal aspects and gene-expression regulating germ cell fate (Ma et al, 2019; Niu et al, 2019; Sasaki et al, 2016)

Methods

Results

Discussion

Conclusion