View Original Link:

https://www.schn.health.nsw.gov.au/files/factsheets/undescended_testes-en.pdf

When a baby boy is growing in the uterus, his testes form inside his abdomen before moving down into the scrotum. In full-term babies, both testes are generally down in the scrotum. Each testis needs to lie in the scrotum for it to develop normally.