Skip to content
Login Register

#germ cells

3 public questions tagged with this topic.

Developmental biology Basics

Cells specifically set aside for reproduction in an organism are termed:

Weismann introduced germ-plasm theory distinguishing immortal lineage carrying hereditary information from mortal body-building lineage. Germ cells include primordial germ cells, spermatogonia, oogonia, specified early via BMP4 and Blimp1 signaling, migrating to gonadal ridge, undergoing meiosis to haploid gametes. Somatic cells constitute supporting tissues such as skin, muscle, neurons that die with individual. This separation explains why acquired somatic mutations are not typically inherited, while germline mutations transmit to offspring. Protecting germ cells from differentiation and maintaining pluripotency networks ensures continuity of species across generations.

Ref: Weismann, Germ-Plasm Theory 1893; Gilbert, 12th ed., Chapter 1: Germ versus somatic cells.

View Details
Drosophila -l

Pole cells in Drosophila embryo give rise to:

Pole cells arise at posterior pole early, incorporating germ plasm containing oskar, vasa helicase, nanos and mitochondrial ribosomal RNAs organized within polar granules. They bud from blastoderm before cellularization via actin-dependent budding, cease division early and maintain germ lineage transcriptional quiescence via Polar granule component suppressing transcription. During gastrulation they involute with posterior midgut, migrate through midgut lumen and actively move towards dorsal mesoderm coalescing with somatic gonadal precursors to form embryonic gonad. Genetic lineage tracing demonstrates pole cells contribute exclusively to germ cells differentiating into sperm or eggs providing continuity across generations.

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 9: Pole cells as primordial germ cells.

View Details
Fertilization in mammals-lll

Pole cells give rise to:

Pole cells are earliest identifiable primordial germ cell precursors in Drosophila, formed at posterior pole of syncytial blastoderm via inheritance of germ plasm containing Oskar protein, Vasa, Nanos mRNA and mitochondria. Cellularization incorporates these determinants into cluster of pole cells that detach and migrate through midgut into gonadal mesoderm coalescing into gonad. Genetic ablation of Oskar eliminates pole cells causing sterility while somatic lineages remain intact. They do not contribute to neural, epidermal or muscle soma; they exclusively generate functional gametes, transmitting genomic continuity via preformation rather than epigenetic induction.

Ref: Rongo et al., Development 1997: Pole cells and germ plasm determinants Oskar Vasa specifying Drosophila germ line.

View Details