Reproductive system

Scrotum

A pouch of skin that holds and protects the testes and keeps them at the right temperature for sperm production.

Penis

The organ that delivers sperm into the female reproductive system during sexual intercourse.

Testis (plural: testes)

Organs that produce sperm and the hormone testosterone.

Epididymis

A tube where sperm mature and are stored after being made in the testes.

Urethra

A tube that carries sperm (mixed with fluids as semen) out of the body through the penis during ejaculation.

Prostate gland

Adds fluid to sperm to help form semen; the fluid nourishes and protects the sperm.

Seminal vesicle

Produces a sugary fluid that provides energy for sperm and is part of semen.

Bladder

Stores urine; not directly part of reproduction, but it shares a connection with the urethra.

Vas deferens

A tube that carries sperm from the epididymis to the urethra before ejaculation.

Semen

A mixture of sperm and fluids from glands (like the prostate and seminal vesicles) that helps sperm survive and move.

Puberty

The stage of life when a person's body becomes able to reproduce, involving physical and hormonal changes like sperm production in males.

Oocytes

Immature egg cells that develop into ova (eggs) for reproduction.

Uterus

A muscular organ where a fertilized egg implants and grows into a baby.

Cervix

The lower part of the uterus that opens into the vagina; it controls entry to and from the uterus.

Vagina

The muscular canal that receives sperm during intercourse and serves as the birth canal.

Follicle

A small sac in the ovary that contains and nourishes a developing oocyte.

Ovum (plural: ova)

A mature egg cell ready to be fertilized by sperm.

Oviduct (also called fallopian tube)

The tube where the egg travels from the ovary to the uterus; fertilization usually happens here.

Ovary

Organs that produce oocytes (eggs) and female hormones like estrogen.

Polar body

A small cell formed during egg development that usually dies; it helps ensure the ovum has the right amount of genetic material.

Follicle-Stimulating Hormone (FSH)

This hormone is released by the pituitary gland. During the first part of the menstrual cycle, FSH stimulates the growth and maturation of ovarian follicles (which contain eggs).

Luteinizing Hormone (LH)

Also released by the pituitary gland, LH works with FSH to trigger ovulation. A sudden surge in LH causes the mature follicle to release an egg (ovulation).

Estrogen

Produced by the developing follicles, estrogen helps to build up the uterine lining (endometrium) in preparation for a potential pregnancy. Estrogen levels rise in the first half of the cycle and peak just before ovulation.

Progesterone

After ovulation, the empty follicle becomes the corpus luteum, which secretes progesterone. This hormone prepares the uterine lining for potential implantation of a fertilized egg. If pregnancy does not occur, progesterone levels drop, leading to menstruation.

Morula

A solid ball of cells formed after a fertilized egg divides several times.

Blastocyst

A hollow ball of cells that forms after the morula; it implants in the uterus and becomes the embryo.

Chorion

The outer membrane that forms part of the placenta and helps exchange nutrients between mother and baby.

Amnion

The membrane that surrounds the embryo and fills with fluid to protect it.

Embryo

The early stage of development from implantation until about 8 weeks, when organs start forming.

Umbilical cord

The cord that connects the embryo (or fetus) to the placenta; it carries oxygen and nutrients in, and waste out.

Allantois

A structure involved in early fluid and waste exchange between the embryo and mother; helps form part of the umbilical cord.

Yolk sac

An early source of nutrients for the embryo and the site of initial blood cell formation.

Fetal portion of the placenta

Made from the chorion; part of the placenta that comes from the baby and helps absorb nutrients.

Maternal portion of the placenta

Comes from the mother’s tissue; provides blood supply and nutrients to support the developing baby.

Morula

A solid ball of cells formed after a fertilized egg divides several times.

Blastocyst

A hollow ball of cells that forms after the morula; it implants in the uterus and becomes the embryo.

Chorion

The outer membrane that forms part of the placenta and helps exchange nutrients between mother and baby.

Amnion

The membrane that surrounds the embryo and fills with fluid to protect it.

Embryo

The early stage of development from implantation until about 8 weeks, when organs start forming.

Umbilical cord

The cord that connects the embryo (or fetus) to the placenta; it carries oxygen and nutrients in, and waste out.

Allantois

A structure involved in early fluid and waste exchange between the embryo and mother; helps form part of the umbilical cord.

Yolk sac

An early source of nutrients for the embryo and the site of initial blood cell formation.

Fetal portion of the placenta

Made from the chorion; part of the placenta that comes from the baby and helps absorb nutrients.

Maternal portion of the placenta

Comes from the mother’s tissue; provides blood supply and nutrients to support the developing baby.