Human Reproduction

• Acrosome


  An organelle in the tip of a sperm containing hydrolase enzymes which digest the zona pellucida of a secondary oocyte
• Amniotic fluid


  The liquid surrounding the embryo in the amniotic sac that protects the foetus and acts as a shock absorber
• Blastocyst


  A ball of cells that arises from the repeated mitotic divisions (cleavage) of a zygote
• Cervix


  A neck of tissue that connects the uterus and the vagina and protects the fetus
• Chorionic villi


  Finger-like projections that arise from part of the placenta known as the chorion and provide a large surface area for the exchange of products between maternal and fetal blood
• Corona radiata


  An outer layer of follicular cells that protect the secondary oocyte in the oviduct
• Corpus luteum


  A mass of cells that forms from the Graafian follicle after ovulation. It serves as a temporary endocrine structure during pregnancy, secreting progesterone
• Cortical granules


  Secretory organelles found in oocytes that, upon entry of a sperm, fuse with the plasma membrane and harden the zona pellucida to prevent polyspermy
• Endometrium


  The inner lining of the uterus, which, during the menstrual cycle, thickens in preparation for embryo implantation
• Epididymis


  A coiled tube in the male reproductive system that links a testicle to a vas deferens and stores sperm prior to ejaculation
• Female reproductive system


  An organ system in females that includes the ovaries, oviducts, uterus, endometrium, cervix and vagina
• Fertilisation


  The fusion of the nuclei of a male and female gamete to form a zygote
• Follicle-stimulating hormone (FSH)


  A hormone secreted by the anterior pituitary gland that binds to follicle cells, stimulating them to mature and secrete oestrogen
• Gametogenesis


  A sequence of nuclear and cellular divisions that result in the production of gametes
• Germinal epithelium


  A surface layer of cells surrounding the ovaries in females and testicles in males that is involved in gametogenesis
• Graafian follicle


  A mature fluid-filled follicle in the ovary within which an egg cell develops
• Human chorionic gonadotropin (hCG)


  A hormone secreted by the developing embryo that maintains the corpus luteum during early pregnancy
• Implantation


  The early stage of pregnancy in which the blastocyst adheres and sinks into the endometrium
• Intervillous spaces


  Spaces between the chorionic villi that contain maternal blood
• Leydig cells


  Cells located adjacent to the seminiferous tubules in the testes that secrete testosterone. Also known as interstitial cells of Leydig
• Luteinising hormone (LH)


  A hormone secreted by the anterior pituitary gland that initiates ovulation and stimulates the development of the Graafian follicle into a corpus luteum
• Male reproductive system


  An organ system in males which includes the scrotum, testes, epididymis, vas deferens, seminal vesicles and prostate gland
• Menstrual cycle


  The monthly cycle in women that involves the development of the endometrium, ovulation and the shedding of the endometrium
• Oestrogen


  A female sex hormone secreted by a mature follicle that inhibits the production of FSH and causes a surge in LH production. During pregnancy, it stimulates uterine growth and the development of the mammary glands
• Oogenesis


  Gametogenesis in females that takes place in the ovaries and results in the production of secondary oocytes
• Oogonia


  Immature female reproductive cells that have formed from primordial germ cells and mature to give primary oocytes
• Ovary


  An organ in the female reproductive system responsible for the production of egg cells in follicles
• Oviducts


  The tubes that transport egg cells from the ovaries to the uterus. They are the site of fertilisation and are commonly known as fallopian tubes
• Ovulation


  The release of an ovum from a mature ovarian follicle into the oviduct
• Ovum


  The female haploid gamete produced by gametogenesis
• Oxytocin


  A hormone secreted by the posterior pituitary gland that triggers the contraction of the uterus wall. It is controlled by a positive feedback mechanism
• Penis


  The male sex organ that penetrates the vagina and releases sperm
• Placenta


  A temporary organ attached to the lining of the uterus during pregnancy. It has a variety of roles including the exchange of gases and nutrients, serving as a barrier between fetal and maternal blood, and hormonal control
• Polar body


  A haploid cell produced during meiosis in females that does not have the ability to be fertilised
• Primary follicle


  An immature ovarian follicle surrounded by two layers of follicular cells
• Primary oocyte


  A diploid oocyte that has undergone growth but has not completed its first meiotic division
• Primary spermatocyte


  A diploid spermatocyte that has undergone growth but has not completed its first meiotic division
• Progesterone


  A female sex hormone secreted by the corpus luteum that causes the development of the endometrium and inhibits the production of FSH and LH. During pregnancy, it suppresses contractions of the uterine wall
• Prolactin


  A hormone secreted by the anterior pituitary gland that stimulates lactation during and after birth
• Prostate gland


  A gland found between the bladder and the penis that secretes an alkaline fluid to neutralise vaginal acidity