"And made his progeny from a quintessence of the nature of a fluid despised." [Al-Qur'an 32:8]
The Arabic word sulâlah means quintessence or the best part of a whole. We have come to know now that only one single spermatozoon that penetrates the ovum is required for fertilization, out of the several millions produced by man. That one spermatozoon out of several millions is referred to in the Qur'an as sulâlah. Sulâlah also means gentle extraction from a fluid. The fluid refers to both male and female germinal fluids containing gametes. Both ovum and sperm are gently extracted from their environments in the process of fertilization.
(from "The Quran and Modern Science, Compatible or Incompatible?" by "Dr. Zakir Abdul Karim Naik" published by Darussalam)