Summary
Highlights
Humans inherit traits from both parents due to sexual reproduction, involving the joining of two sex cells (gametes) in a process called fertilization. Male and female reproductive systems mature during puberty to enable offspring production.
The testes produce sperm, the male gametes, and are located in the scrotum for optimal temperature. Sperm ducts carry sperm to the urethra, where it mixes with glandular secretions to form semen, which aids in sperm delivery to the female reproductive system.
The ovaries release female gametes (eggs or ova) monthly via ovulation. Females are born with all their eggs. During puberty, the monthly cycle of egg maturation and release begins as part of the menstrual cycle. After ovulation, the egg travels through the fallopian tube towards the uterus.
During sexual intercourse, semen enters the vagina, and sperm swim towards the uterus. If a sperm reaches and fertilizes an egg in the fallopian tube, conception occurs. An egg is viable for 24 hours, while sperm can survive for up to 5 days, creating a 6-day window for potential pregnancy.
A fertilized egg (zygote) divides and implants in the uterine lining. If unfertilized, the egg and uterine lining are shed during menstruation. In pregnancy, the ball of cells differentiates to form the embryo and placenta. The placenta facilitates the exchange of nutrients, oxygen, and waste products between the mother and embryo.
By the end of week 8, the embryo is called a fetus, possessing all organs but still very small. The fetus continues to develop for 38-42 weeks (gestation) until it can survive independently after birth.