Colostrum: a fluid rich in antibodies and low in fat, secreted by the mother's breasts at the birth of a baby, before the true milk starts to flow.

Corpus Luteum: a body which forms in each ovary after a Graafian follicle has ruptured.

Oestrogen: steroid hormone which stimulates the development of secondary sexual characteristics in females at puberty.

Hormone: a chemical secreted by endocrine glands that can regulate the functions of specific organs.

Inferior Vena Cava: the main vein carrying blood from the lower part of the body to the heart.

Progesterone: a hormone which is produced in the second part of the menstrual cycle by the Corpus Luteum and which stimulates the formation of the placenta if an ovum is fertilized.