Blastocyst – An embryo that is five to six days old and has formed a fluid-filled sac. The outer layer of cells will become the placenta, while the inner cell layer will become the fetus itself.
Cervix – The cervix is the lower end of the uterus, located at the top of the vagina, and is a passageway between the vagina and uterus.
Egg – See Oocyte.
Embryo – The fertilized egg after cell division begins until the start of the third month of pregnancy.
Epididymis – A convoluted tubule adjacent to each testis; carries sperm to the vas deferens.
Estrogen – The female sex hormone produced by the follicles, responsible for many functions including the development of the lining of the uterus.
Fallopian Tubes – Two thin tubes that extend from each side of the uterus toward the ovaries. They are a passageway for eggs and sperm and site of fertilization.
Fertilization – The union of sperm and egg.
Follicle – A small fluid-filled sac in the ovary containing the egg.
Follicle Stimulating Hormone (FSH) – Hormone secreted by the pituitary gland in the brain that stimulates the maturation of ovarian follicles in females and sperm cell maturation in males.
Luteinizing Hormone (LH) – Hormone secreted by the pituitary gland in the brain that stimulates the release and maturation of eggs in females and testosterone production in males.
Oocyte – The female sex cell, or egg, produced in the ovaries and released from a follicle during ovulation; also called ovum.
Ovaries – Female reproductive glands in which the ova, or eggs, are formed. The ovaries are located in the pelvis, one on each side of the uterus.
Ovulation – The release of the egg from the ovary.
Progesterone – A hormone secreted by the ovary after ovulation has occurred. It prepares the lining of the uterus for implantation of a fertilized egg.
Prostate – A gland in the male reproductive system just below the bladder. It secretes seminal fluid, a milky substance that combines with sperm (produced in the testicles) to form semen.
Semen – The fluid that is released through the penis during ejaculation. Semen is made up of sperm from the testicles and fluid from the prostate and other glands.
Sperm – The male reproductive cell, formed in the testicle. A sperm unites with an egg to form an embryo.
Testes – Also called testicles. Pair of male sex glands that produce sperm and male hormone testosterone.
Testosterone – A hormone produced by the testes, responsible for the development of male secondary sex characteristics and functioning of the male reproductive organs.
Uterus – The pear-shaped organ in women that holds and nourishes the growing embryo and fetus. Commonly called the womb.
Vas Deferens – Tube through which sperm travel from the epididymis as they mature.
Zygote – The fertilized egg before cell division begins.