<P> Most first ejaculations (90 percent) lack sperm . Of the few early ejaculations that do contain sperm, the majority of sperm (97%) lack motion . The remaining sperm (3%) have abnormal motion . </P> <P> As the male proceeds through puberty, the semen develops mature characteristics with increasing quantities of normal sperm . Semen produced 12 to 14 months after the first ejaculation liquefies after a short period of time . Within 24 months of the first ejaculation, the semen volume and the quantity and characteristics of the sperm match that of adult male semen . </P> <Table> Semen development during puberty <Tr> <Th> Time after first ejaculation (months) </Th> <Th> Average volume (milliliter) </Th> <Th> Liquefaction </Th> <Th> Average sperm concentration (million sperm / milliliter) </Th> </Tr> <Tr> <Td> 0 </Td> <Td> 0.5 </Td> <Td> No </Td> <Td> 0 </Td> </Tr> <Tr> <Td> 6 </Td> <Td> 1.0 </Td> <Td> No </Td> <Td> 20 </Td> </Tr> <Tr> <Td> 12 </Td> <Td> 2.5 </Td> <Td> No / Yes </Td> <Td> 50 </Td> </Tr> <Tr> <Td> 18 </Td> <Td> 3.0 </Td> <Td> Yes </Td> <Td> 70 </Td> </Tr> <Tr> <Td> 24 </Td> <Td> 3.5 </Td> <Td> Yes </Td> <Td> 300 </Td> </Tr> </Table> <Tr> <Th> Time after first ejaculation (months) </Th> <Th> Average volume (milliliter) </Th> <Th> Liquefaction </Th> <Th> Average sperm concentration (million sperm / milliliter) </Th> </Tr>

When does a human male begin to make sperm
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