Germcell

Germ cell refers to a reproductive cell lineage that gives rise to gametes in sexually reproducing organisms. In animals, the germline comprises the cells that pass genetic information to the next generation. Primordial germ cells (PGCs) are the embryonic precursors that migrate to developing gonads and later differentiate into mature gametes. Somatic cells are the non-reproductive cells of the body.

Development typically involves PGCs originating outside the gonads and migrating to the gonadal ridges, where they become gonocytes or later gonadal gametes. In males, spermatogonial stem cells divide and differentiate to form primary spermatocytes, which undergo meiosis I to yield secondary spermatocytes and then meiosis II to form haploid spermatids that mature into spermatozoa. In females, oogonia proliferate during fetal life to form primary oocytes, which arrest in prophase I; after puberty, select follicles resume meiosis to produce a haploid secondary oocyte and a polar body, with meiosis II completed only upon fertilization.

Function and heredity: Germ cells are the only cells that contribute genetic material to offspring in sexually reproducing organisms. They are diploid in the germline before meiosis and become haploid gametes through meiosis; sexual union restores diploidy in the zygote.

Germline mutations and tumors: Mutations in germ cells can be transmitted to progeny. Germ cell tumors can arise from germ cells in the testes or ovaries, including seminomas and dysgerminomas, as well as other tumor types in some contexts.