In vitro production of haploid germ cells

A method of in vitro spermatogenesis comprising:

• isolating a plurality of Sertoli cells and a plurality of undifferentiated diploid germ cells from a testis of a male mammal;
• aggregating the Sertoli cells and the germ cells to yield Sertoli-germ cell aggregates;
• encapsulating the Sertoli-germ cell aggregates to yield a plurality of tubule-like structures containing both Sertoli cells and germ cells;
• transferring the tubule-like structures to a culture medium;
• and
• culturing the tubule-like structures under conditions effective to allow the Sertoli cells and the germ cells to interact, whereby the germ cells progress through spermatocytogenesis and meiosis to produce a plurality of differentiated haploid spermatids.