Does male seed come from between the back and the ribs? What does 86:7 mean?

While the actual meaning of this is best known by God, it has often been translated in the manner described in the question. However, as is the case with other descriptions found within the Qur'an, the reality may be discovered later. Linguistically, it seems possible that the water, or fluid, that is referred to in the verse could emanate from anywhere between the front and back of the body, which would include the testes. It could also be referring to the combination of seminal and prostatic fluid. Perhaps as medical science catches up to Qur'anic explanation, we will see clearer evidence in the future.