Spermatogonium \Sper`ma*to*go"ni*um\, n. [NL., fr. Gr. ????, ???, sperm + ??? offspring.] (Physiol.) A primitive seminal cell, occuring in masses in the seminal tubules. It divides into a mass (spermosphere) of small cells (spermoblast), which in turn give rise to spermatozoids.