Gonocytes, the forgotten cells of the germ cell lineage

Abstract

Male germ cells, the repository cells of the genome, comprise several successive developmental stages starting in the embryo and ending up with the spermatozoon. Gonocytes represent the fetal and neonatal stages preceding the formation of spermatogonial stem cells. Recent findings shows that germline stem cells can be driven to pluripotency and used as alternative for embryonic stem cells prompted more effort in identifying the processes regulating the development of their precursors, the testicular gonocytes. Also called pre- or pro-spermatogonia, gonocytes represent not one, but several successive developmental stages between the time at which the germ cell becomes resident in the forming fetal testis to the time it migrates to the basement membrane of the seminiferous cord to adopt a spermatogonial phenotype. This review summarizes the findings regarding the genetic identity of gonocytes, providing a description of the "common" gene expression profiles of fetal and neonatal gonocytes, as well as information on the main regulatory factors of gonocyte functions. A better comprehension of gonocyte development should help in the understanding of how germline stem cells are formed, possibly providing valuable clues on the origins of germ cell tumors or infertility.

Neonatal Gonocyte Differentiation in Mongolian GerbilMeriones unguiculatusInvolves Asynchronous Maturation of Seminiferous Cords and Rapid Formation of Transitional Cell Stage

“…There is much disagreement about the behavior, properties and nomenclature of prespermatogenic germ cell populations. The term gonocyte was originally proposed by Clermont and Perey (1957) and it currently refers to the fetal germ cells derived from primordial germ cells that exhibit distinctive morphological characteristics as well as stages of quiescence and mitotic activity (de Rooij and Russell, 2000;Nagano et al, 2000;Culty 2009). Other authors employed the terms prospermatogonia and prespermatogonia to define the cells derived from primordial germ cells (Hilscher et al, 1974;Wartenberg, 1976;Byskov, 1986).…”

“…Relocation of gonocytes is already observed at one day of age but continues until the second postnatal week, and is followed by their rapid differentiation into the prospermatogonial transition phase. As recently emphasized by Culty (2009), gonocytes can be considered ''the forgotten cells of the germ cell lineage,'' as they are surely the least investigated germ cell type (only 100-200 papers versus several thousand directed at mature types of germ cells). Furthermore, most articles focus on rats and mice (Culty, 2009).…”

“…As recently emphasized by Culty (2009), gonocytes can be considered ''the forgotten cells of the germ cell lineage,'' as they are surely the least investigated germ cell type (only 100-200 papers versus several thousand directed at mature types of germ cells). Furthermore, most articles focus on rats and mice (Culty, 2009). The establishment of main morphological and temporal events during Gn maturation in gerbils is essential for investigating the differentiation of and unanswered questions about this germ cell.…”

High‐purity flow sorting of early meiocytes based on DNA analysis of guinea pig spermatogenic cells

“…1). During the first days after birth, guinea pig specimens display a great majority of 2C cells, and few 4C ones that correspond to mitotically dividing spermatogonia/ prespermatogonia (44) and somatic cells in G2 (Fig. 1A,A', 3 days post partum).…”

Effects of extracellular matrices and lectin Dolichos biflorus agglutinin on cell adhesion and self-renewal of bovine gonocytes cultured in vitro

“…Therefore, our results suggest the possibility that DBA-precoated plates may have resulted in transit characteristics of gonocytes towards SSCs and/or spermatogonia. This hypothesis could be supported by the evidence that characteristic changes of gonocytes have been observed when they reach the basement membrane of the seminiferous tubules (Culty 2009), and the proliferative activity of cultured gonocytes seems to be induced by the transition towards SSCs and/or spermatogonia in mice (Kanatsu-Shinohara et al 2005). The finding that the characteristic changes in colony formation and the expression of pluripotency-related genes support both the growth of colonies and the differentiation of some gonocytes indicates that the glycan epitope of gonocytes may be associated with further progression for the differentiation towards SSCs and/or spermatogonia during postnatal developmental stages.…”