99 Fun Facts About Female Anatomy

The human uterus is usually described as being shaped like which fruit?

A pear: it sits just behind and almost over the bladder, which is why a growing pregnancy makes women need to urinate more often.

What is the inner lining of the uterus, shed during a period, called?

Endometrium: each cycle it thickens to receive an embryo, and if none implants, the lining breaks down and leaves the body as a period.

The thick muscular wall of the uterus that contracts during childbirth is called what?

The myometrium: it stretches during pregnancy, letting the uterus grow to several times its usual size before it contracts in labour.

Roughly how many oocytes (immature eggs) are present in the ovaries at birth?

About 1 million: most of them die off naturally, so by puberty well over half are already gone.

Approximately how many eggs does a woman release over her whole reproductive life?

About 400: usually just one egg is released each menstrual cycle, so decades of cycles add up to only a few hundred.

Which test collects cells from the cervix to check for signs of cancer?

Pap smear: it spots precancerous changes before cancer develops, which is how cervical screening helps prevent the disease.

Fertilization normally happens in which part of the fallopian tube, its widest section?

The ampulla: from there, tiny hairs lining the tube sweep the fertilized egg, dividing as it goes, down into the uterus.

What are the finger-like projections at the end of each fallopian tube called?

The egg is actually released into the abdominal cavity first; beating cilia on the fimbriae draw it into the tube.

What is the surgical removal of the uterus called?

Hysterectomy: afterwards periods stop for good, and pregnancy is no longer possible.

What is the median length of the human menstrual cycle?

28 days: yet cycles anywhere from 21 to 35 days long count as normal.

Which day is counted as day one of the menstrual cycle?

The first day of bleeding: pregnancies are dated from it too, so at conception a pregnancy already counts as about two weeks along.

What is the medical term for a girl's first period?

Menarche usually comes before a girl ovulates regularly, which is why early periods are often irregular and can take years to settle.

A surge in which pituitary secretion triggers ovulation?

Luteinizing hormone: home ovulation predictor kits work by detecting this surge in urine.

After ovulation, the follicle's remains form a temporary progesterone gland called what?

Corpus luteum is Latin for 'yellow body'; if no pregnancy begins, it breaks down into a white scar called the corpus albicans.

What are Braxton Hicks contractions?

Practice contractions: they're often mistaken for labour, but unlike real labour they don't build up or come closer together.

When a pregnant woman's waters break, which structure has ruptured?

The amniotic sac: if labour doesn't follow soon after it breaks, doctors usually offer to induce labour because of the risk of infection.

What does IVF stand for?

In vitro fertilisation: eggs are fertilised in a lab and the embryo placed in the womb, getting round problems such as blocked or damaged fallopian tubes.

What does the medical term 'amenorrhoea' mean?

Absence of periods: it is normal in pregnancy and breastfeeding, but can also follow sudden weight loss or too much exercise.

What happens to a woman's resting body temperature just after ovulation?

It rises slightly: progesterone released after ovulation lifts it, which is why fertility-awareness methods record temperature every day.

What does it mean when a baby is breech late in pregnancy?

Bottom or feet first: from about 36 weeks, a doctor may try to turn the baby head down by pushing on the mother's belly, a procedure called ECV.

Which condition becomes more likely after menopause, as bone loss speeds up?

Osteoporosis: it can weaken bones so much that even a minor fall, which a healthy bone would withstand, causes a fracture.

The hot flushes of menopause are mainly linked to falling levels of which hormone?

Estrogen: hormone replacement therapy, which supplies it again, can relieve the flushes.

Which bone is the most sexually dimorphic in the human skeleton, and so most reliable for determining sex from remains?

The pelvis: a woman's is larger and broader, a trade-off between efficient walking and a birth canal wide enough for a baby's head, as the obstetrical dilemma hypothesis proposes.

Which skin condition, nicknamed the 'mask of pregnancy', causes dark patches on the face?

Melasma: sunlight can darken the patches or bring them back after they fade, so protecting the skin from the sun matters.

What is the most common cause of heavy bleeding just after childbirth?

The uterus failing to contract: after birth its muscle normally clamps shut the blood vessels where the placenta was attached.

Which mineral are women with heavy periods most at risk of running low on?

Iron: blood lost each period carries iron with it, and heavy periods and pregnancy are very common causes of iron deficiency anaemia.

What is usually the first physical sign of puberty in girls?

Breast budding: it usually begins between 8 and 13, so signs of puberty before 8 can mean early puberty, which a GP can check.

What is the medical term for the onset of breast development at puberty?

In the two years after it, the uterus, ovaries and follicles all grow; menarche follows later.

Besides connective tissue, which two tissue types make up the breast?

Adipose and glandular: breasts with more glandular tissue look denser on a mammogram, where tumours can be harder to spot.

The suspensory bands that support the breast are named after which English surgeon?

Cooper: Sir Astley Cooper, who described the ligaments in 1840, had removed a cyst from King George IV's scalp and was made a baronet.

What is the name of the pigmented area of skin surrounding the nipple?

The areola: its small Montgomery glands release an oil that protects the skin during breastfeeding.

What is colostrum?

An early form of breast milk: thick and golden yellow, colostrum carries antibodies that help protect a newborn against infection.

Which hormone is the main driver of milk production during breastfeeding?

Prolactin: high levels while breastfeeding are linked to suppressed ovulation, one reason exclusive breastfeeding can delay periods returning.

Which hormone contracts the cells around the milk-producing alveoli in the "let-down" reflex?

Oxytocin: a synthetic version is given through a drip to start or speed up labour.

Pre-eclampsia in pregnancy is marked mainly by a new rise in what?

Blood pressure: it often comes with protein in the urine, and it usually eases only once the baby and placenta are delivered.

During childbirth the cervix must dilate to more than what diameter?

10 cm: that is roughly how wide the opening must be for a full-term baby's head to pass through.

Around ovulation, cervical mucus becomes thin and more what, to help sperm survive?

Alkaline: the thinner mucus also turns stretchy, a quality called Spinnbarkeit, which lets sperm enter the uterus.

The word 'vagina' comes from the Latin for what?

A sheath or scabbard: the Romans never used the word for anatomy; it entered English medicine only in the 1680s.

Which bacteria dominate a healthy vagina and keep it acidic?

Lactobacilli: their lactic acid holds germs in check, and when the natural balance of bacteria shifts, bacterial vaginosis can follow.

What do Bartholin's glands produce?

Lubricant: the glands secrete mucus that moistens the vagina, and if a gland's opening gets blocked, fluid builds up into a painful Bartholin's cyst.

Skene's glands are sometimes called the 'female' version of which male organ?

The prostate: like it, Skene's glands produce prostate-specific antigen, the protein PSA blood tests measure to screen for prostate cancer.

What does the medical term 'mittelschmerz' describe?

Ovulation pain: the word is German for 'middle pain', because it strikes around the middle of the menstrual cycle.

A Barr body, seen in the cells of females, is what?

An inactivated X chromosome: Murray Barr and his student spotted it in 1949, and in 1961 Mary Lyon explained that one X in each female cell is switched off.

Which hormone, produced after implantation, do home pregnancy tests detect?

Human chorionic gonadotropin: cells around the growing embryo make it after implantation, so a test taken too early may give an unreliable result.

The word 'placenta' comes from a Latin word for what, referring to the organ's shape?

A flat cake: if the placenta attaches low and covers the cervix, called placenta praevia, the baby usually has to be born by caesarean.

Roughly how much does a full-term human placenta weigh?

About 500 grams: it lets oxygen and nutrients pass between mother and baby without their bloodstreams ever mixing.

About how big is a typical non-pregnant adult uterus?

A fist: in pregnancy it grows so much that it can push the stomach muscles apart, often leaving a gap after the birth.

Which condition occurs when a fertilised egg implants outside the womb, usually in a fallopian tube?

An ectopic pregnancy cannot be saved, and if the tube ruptures it can be life-threatening, though that is uncommon and treatable if caught quickly.

What is an episiotomy, sometimes done during childbirth?

A cut widening the vaginal opening: it can help prevent a severe tear, or speed up the birth when the baby needs to be born quickly.

Which marine mammals are among the few animals whose females live for decades after menopause?

Orcas are led by their eldest females, who stop breeding yet can live to 80 or more, guiding sons, daughters and grandchildren in the same family group.

A myth drawn from the story of Adam and Eve claims women have one more of which bone than men?

A rib is the bone Eve is made from in Genesis, yet both sexes have 12 pairs; Vesalius caused a controversy by counting them in 1543.

Which cell structures carry their own small set of genes, inherited almost entirely from the mother?

Mitochondria in sperm are usually destroyed by the egg after conception, so their DNA lets researchers trace a maternal line far back in time.

Which tube is only about 4 cm long in women, one reason bladder infections are more common than in men?

The urethra in women runs from the bladder to an opening just below the clitoris, while the male one averaged over 22 cm in one study of 109 men.

Which inherited eye condition affects about 1 in 12 men but only about 1 in 200 women?

Color blindness is rarer in women because the red-green genes sit on the X, and a woman's second copy usually covers for a faulty one.

The linea nigra, a brownish line on the abdomen in pregnancy, typically runs from the pubis up to where?

The navel is where it usually ends, though it can climb higher; a pigment signal from the placenta darkens the line, and it fades away after the birth.

Which rare, life-threatening illness led Procter & Gamble to recall its super-absorbent Rely tampons in 1980?

Toxic shock syndrome comes from toxins made by bacteria that can multiply on a tampon left in too long, though it can also follow an infected wound or burn.

Which virus, the target of a vaccine offered to young teenagers, causes nearly all cases of cervical cancer?

Human papillomavirus is so common that most people catch it at some point, yet just two of its strains, 16 and 18, account for about 70% of cervical cancers.

Besides primates, elephant shrews and one spiny mouse, which animals are among the few mammals known to menstruate?

Bats complete a very short list, because most female mammals have an estrous cycle in which the womb lining is quietly reabsorbed instead of being shed.

Which exercises, described by an American gynecologist in 1948, strengthen the muscles that hold up the bladder?

Kegels carry Arnold Kegel's name, although a woman, Margaret Morris, had published the same idea in 1936 and received little credit for it.

Which severe form of pregnancy sickness put Catherine, Princess of Wales, in hospital during her first pregnancy?

Hyperemesis gravidarum means vomiting so relentless that a woman loses at least 5% of her body weight, and it is treated as an emergency because of dehydration.

Which word for a mother first feeling her baby move was once a key legal boundary in English common law?

Quickening tends to come at around 20 weeks in a first pregnancy and a little earlier in later ones, and it can feel like light tapping or fluttering.

Which pregnancy condition, screened for at 24 to 28 weeks, clears up in about 90% of cases after the birth?

Gestational diabetes is any glucose intolerance first recognised in pregnancy, and when poorly treated it raises the odds of an unusually large baby.

Which benign muscle growths in the womb, also called leiomyomas, develop in up to 80% of women by age 50?

Fibroids usually go unnoticed, since most women who have them get no symptoms and need no treatment, while others have heavy or painful periods.

Which yeast causes the vaginal infection that about three-quarters of women get at least once in their lives?

Candida also lives harmlessly in the vaginas of roughly one in ten healthy women, and tends to flare after antibiotics or when immunity is low.

Which sexually transmitted infection causes no symptoms in about 70% of infected women yet can lead to infertility?

Chlamydia that goes undetected spreads upward in about half of symptomless women, inflaming the womb, tubes and ovaries.

Which instrument, examples of which were found at Pompeii, holds the vagina open during a cervical examination?

A speculum in its modern form began as a pewter spoon, which the American surgeon Marion Sims bent into the shape of a duck's beak.

Which kind of ovarian growth can contain clumps of long hair, teeth, bone and even thyroid tissue?

A dermoid cyst grows from germ cells that can turn into almost any tissue, and because it develops slowly from mature tissue it is nearly always benign.

Which term describes the non-identical twins that run in families through a tendency to release more than one egg?

Dizygotic twins each grow from their own egg and sperm, so they are no closer genetically than ordinary siblings and, very rarely, have different fathers.

Which B vitamin are women advised to take before and during early pregnancy to protect the baby's developing spine?

Folic acid is needed in the first few weeks, often before a woman knows she is pregnant, which is why many countries fortify food with it by law.

In humans, the ovaries are homologous to which pair of male organs, sharing their role as sex glands?

The testes are the male match, and Herophilus, the ancient Greek physician who first described the ovaries, even called them the "female testes".

The cervix, the narrow lower end of the womb, takes its name from the Latin word for which body part?

The neck is what "cervix" means in Latin, a word that could also describe any narrowed part of an object, as in the full medical name cervix uteri.

The words "menstruation" and "menses" both derive from the Latin word "mensis", which means what?

Month is the meaning of "mensis", a word that is itself related to the ancient Greek for moon and to the roots of the English words month and moon.

Which metal gives the hormone-free IUD its power, releasing ions that damage sperm and stop them moving?

Copper makes the coil one of the most effective contraceptives available, and a single device can keep working for up to twelve years.

What is the medical term for period pain, which is driven by chemicals that make the womb muscle tighten?

Dysmenorrhea is caused by prostaglandins released from the womb, which is why painkillers such as ibuprofen, which block their production, are effective.

What lines the inside of each fallopian tube and beats in waves to help move an egg toward the womb?

Cilia do the job together with squeezing of the tube's muscular wall, and damage to them can stop an egg or sperm from getting through.

What are the ridged folds in the wall of the vagina, which let it stretch during childbirth, called?

Rugae add surface area so the wall can extend, and the same name is given to the folds inside the stomach, which flatten out as it fills with food.

Which part of the brain releases pulses of GnRH, the signal that sets the whole menstrual cycle in motion?

The hypothalamus sends GnRH in bursts, and the size and frequency of those bursts tell the pituitary which of its two reproductive signals to release.

What is the hollow ball of 100 to 200 cells that implants in the womb about a week after conception?

A blastocyst forms about five days after conception, when a fluid-filled cavity opens up inside what had been a solid ball of cells.

The G-spot is named after which German gynecologist, who in 1929 described the first well-recorded IUD?

Ernst Gräfenberg lost his Berlin hospital post in 1933 because he was Jewish; the term G-spot was coined in his honor only in the early 1980s.

The mature follicle of the ovary is named after which 17th-century Dutch physician, who studied it in rabbits?

Regnier de Graaf reasoned from rabbits that the follicle held the egg, though he never saw one; a mammalian egg was first described only in 1827.

Which paired embryonic ducts, which wither away in males, develop into the fallopian tubes, womb and upper vagina?

Müllerian ducts form in every embryo, but in males a chemical signal makes them degenerate, leaving the neighboring Wolffian pair to take over.

The pouch between the womb and rectum, the lowest point of a woman's abdominal cavity, is named after which anatomist?

James Douglas, a Scottish anatomist and physician to Queen Caroline, gave it his name; as the lowest point, it is where pus and fluid tend to collect.

Which coat of proteins surrounds a human egg and stops more than one sperm from getting in?

The zona pellucida also lets in only sperm of the right species, and about five days after conception the embryo hatches out of it.

When a human egg divides unevenly during meiosis, what is the tiny cast-off cell with almost no cytoplasm called?

A polar body takes half of the genetic material but hardly any of the cytoplasm, so the egg keeps the stored nutrients an embryo will need.

Human eggs begin meiosis before a girl is born, then pause for years at which stage of cell division?

Prophase I is where each egg waits, holding four copies of its genome, which seems to help it repair DNA damage during the long pause.

Which gene, normally carried on the Y, steers an embryo toward male development about six to eight weeks in?

SRY, short for sex-determining region Y, flips a switch in gonads that could otherwise go either way; embryos without a working copy usually develop as female.

What is the vaginal discharge that continues for four to eight weeks after childbirth as the womb heals called?

Lochia starts out red with blood and shreds of membrane, then thins and turns brownish or pink as the weeks pass.

What is the term for cells from a fetus living on in the mother's body long after the pregnancy?

Microchimerism explains why male DNA has turned up in the brains of women who once carried a son; the cells can persist and multiply for decades.

What is the collective term for sex cells such as eggs and sperm, each carrying half a set of genes?

Gametes are haploid, so that when two of them fuse the new cell ends up with one complete set of genetic instructions from each parent.

Cells taken from which woman's cervical tumor in 1951 became HeLa, the first immortal human cell line?

Henrietta Lacks was 31, and the sample was taken without her knowledge; until 1973 the cell line was wrongly credited to a "Helen Lane".

What seals the cervical canal during pregnancy, keeping bacteria out of the womb until labor approaches?

The mucus plug carries antimicrobial agents much like those in nasal mucus, and losing it does not necessarily mean that labor is about to begin.

What is the medical term for a so-called tipped womb, found in up to one in three women?

Retroverted wombs lean back toward the spine instead of tilting forward, and they generally cause no problems with fertility or carrying a baby.

What is the rounded top of the womb, which midwives measure from the pubic bone to track a baby's growth, called?

The fundus lies above the openings of the fallopian tubes, and its height in centimeters roughly matches the weeks of pregnancy from 16 to 36.

The Hogben pregnancy test, widely used from the 1940s to the 1960s, injected a woman's urine into which animal?

A frog given a pregnant woman's sample would lay eggs within a day, and trade in the African species used is blamed for spreading a fungus that has devastated amphibians.

What is the gap that the growing womb can open between the two halves of the "six-pack" muscle called?

Diastasis recti is more common in women who have had several pregnancies, and physical therapy is often enough to close the separation.

Which thin outer layer covers the womb, lying outside its muscular wall and its inner lining?

The perimetrium is a sheet of peritoneum draped over the organ, folding back onto the bladder in front and onto the rectum behind.

Which British pediatrician gave his name to the five-stage scale that tracks physical development through puberty?

James Tanner built it from a two-decade study that followed girls through puberty, and he argued against using the stages to estimate someone's age.

Which score, first published in 1964, rates how ready the cervix is for labor to be induced?

Bishop scoring weighs how soft, thin and open the cervix is and how low the baby sits, and a total of 9 makes a successful induction very likely.

Which autoimmune disease, known for a butterfly-shaped facial rash, is about nine times more common in women?

Lupus strikes mostly during the childbearing years, and only some patients ever develop the classic rash across the cheeks and nose.