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Gonocytes are the precursors of spermatogonia that differentiate in the testis from primordial germ cells around week 7 of embryonic development and exist up until the postnatal period, when they become spermatogonia. Despite some uses of the term to refer to the precursors of oogonia, it was generally restricted to male germ cells. Germ cells operate as vehicles of inheritance by transferring genetic and epigenetic information from one generation to the next. Male fertility is cetered around continual spermatogonia which is dependent upon a high stem cell population. Thus, the function and quality of a differentiated sperm cell is dependent upon the capacity of its originating spermatogonial stem cell (SSC).

History
Gonocytes are described as large and spherical, with a prominent nucleus and two nucleoli. The term, gonocyte, was created in 1957 by Canadian scientists Yves Clermont and Bernard Perey. They considered it essential to study the origin of spermatogonia and carried out a study on rats to investigate this. In 1987, Clermont referred to gonocytes as the cells that differentiate into type A spermatogonia, which differentiate into type B spermatogonia and spermatocytes.

Later studies found that the process from primordial germ cell to spermatogonial development is gradual, without clear gene expression markers to distinguish the precursor cells. A 2006 study found that some gonocytes differentiate straight into committed spermatogonia (type B) rather than spermatogonial stem cells (type A).

Origin of SSC Pool
Gonocytes are long-lived precursor germ cells responsible for the production of spermatogonial stem cells (SSCs). Gonocytes relate to both fetal and neonatal germ cells from the point at which they enter the testis primordial until they reach the base membrane at the seminiferous cords and differentiate. At the time of gasturalation, certain cells are set aside for later gamete development. These cells are called post migratory germ cells (PGCs). The gonocyte population develops from the post migratory germ cells (PGCs) around embryonic day (ED) 15. At this point of development, PGCs become dormant and remain inactiveted until birth. Shortly after birth, the cell cycle continues and the production of postnatal spermatogonia commences. Gonocytes migrate to the basement membrane to proliferate. Gonocytes that do not migrate undergo apoptosis and are cleared from the seminiferous epithelium. Spermatogonia are formed in infancy and differentiate throughout adult life.

Formation of Spermatogonial Lineage
There are currently two proposed models for the formation of the spermatogonial lineage during neonatal development. Both models theorize that the gonocyte population develops from a subset of post migratory germ cells (PGCs) but, differ in the proposed subsets of derived gonocytes. One of the models proposes that the PGCs give rise to a single subset of pluripotent gonocytes that either become SSCs from which progenitors then arise or differentiate into type A spermatogonia directly. The other model proposes that the PGCs give rise to multiple predetermined subsets of gonocytes that produce the foundational SSC pool, initial progenitor spermatogonial population, and initial differentiating type A spermatogonia.