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Narrator: 4 1/2 BILLION YEARS AGO, THE YOUNG PLANET EARTH
WAS A MASS OF COSMIC DUST AND PARTICLES.
IT WAS ALMOST COMPLETELY ENGULFED
BY THE SHALLOW PRIMORDIAL SEAS.
POWERFUL WINDS GATHERED RANDOM MOLECULES FROM THE ATMOSPHERE.
SOME WERE DEPOSITED IN THE SEAS.
TIDES AND CURRENTS SWEPT THE MOLECULES TOGETHER.
AND SOMEWHERE IN THIS ANCIENT OCEAN
THE MIRACLE OF LIFE BEGAN.
THE FIRST ORGANIZED FORM OF PRIMITIVE LIFE
WAS A TINY PROTOZOAN.
MILLIONS OF PROTOZOA POPULATED THE ANCIENT SEAS.
THESE EARLY ORGANISMS WERE COMPLETELY SELF-SUFFICIENT
IN THEIR SEAWATER WORLD.
THEY MOVED ABOUT THEIR AQUATIC ENVIRONMENT
FEEDING ON BACTERIA AND OTHER ORGANISMS.
THEY WERE COVERED
WITH HUNDREDS OF TINY WHIPPING HAIRS CALLED CILIA AND FLAGELLA
THAT MADE MOVEMENT POSSIBLE.
FROM THESE ONE-CELLED ORGANISMS EVOLVED ALL LIFE ON EARTH.
AND THE FOUNDATION OF LIFE, THE CELL, HAS ENDURED UNCHANGED
SINCE THE FIRST ORGANISMS TINY SWAM IN THE CRADLE OF LIFE,
THE SEA.
EVERY LIVING BEING IS MADE UP OF CELLS
THE BASIC UNITS OF LIFE ON EARTH.
AND ALL CELLS REPRODUCE THEMSELVES
BY DIVIDING INTO TWO IDENTICAL CELLS.
THIS IS A SINGLE BODY CELL FROM A HUMAN BEING
AND THIS IS THE PROCESS BY WHICH ALL CELLS REPRODUCE.
NOW THERE ARE TWO CELLS, EACH EXACTLY LIKE THE PARENT.
IN THE CELL'S NUCLEUS
IS THE EXTRAORDINARY CHEMICAL SUBSTANCE DNA.
THE DNA IS CONTAINED IN 46 CHROMOSOMES
IN EVERY CELL OF THE HUMAN BODY.
EACH CHROMOSOME, IN TURN, IS MADE UP OF THOUSANDS OF GENES
DISCRETE SEGMENTS OF DNA WHICH LIE ALONG THE CHROMOSOME.
PENETRATING EVEN DEEPER INTO THE STRUCTURE OF THE CHROMOSOME
WE SEE THE DNA MOLECULES THEMSELVES.
DNA CONTAINS ALL THE GENETIC INFORMATION
OF THE CELL
AND IT IS THE ONLY LIVING SUBSTANCE
CAPABLE OF REPRODUCING ITSELF EXACTLY.
WITHOUT DNA, DUPLICATION, AND THEREFORE LIFE ITSELF
IS NOT POSSIBLE.
ALL DNA IN ALL LIVING ORGANISMS IS CHEMICALLY IDENTICAL.
BUT ITS ARRANGEMENT IN GENES AND CHROMOSOMES DETERMINES
WHAT THE CELLS WILL BECOME:
HERE, A TINY PRIMITIVE ORGANISM, THE PROTOZOAN;
A MASSIVE, COMPLEX MAMMAL, THE ELEPHANT;
A PALM TREE, SWAYING IN THE TROPICAL BREEZE;
OR A HUMAN BEING.
WE ARE ABOUT TO WITNESS, FOR THE FIRST TIME
A WONDROUS AND COMPLEX PROCESS...
THE ACTUAL CONCEPTION AND GROWTH OF A NEW HUMAN BEING.
EACH BEGINNING LIES DEEP INSIDE THE MOTHER'S BODY
IN THE OVARIES.
EACH OVARY CONTAINS A QUARTER OF A MILLION EGG CELLS
WHICH REACH FULL DEVELOPMENT
EVEN BEFORE THE WOMAN HERSELF WAS BORN.
THE EGGS EACH CONTAIN 23 CHROMOSOMES
THE MOTHER'S GENETIC CONTRIBUTION
TO HER FUTURE OFFSPRING.
DURING EACH MENSTRUAL CYCLE, THE OVARIES PRODUCE HORMONES
WHICH STIMULATE THE GROWTH OF A SINGLE ONE OF THESE EGGS.
AT THE MIDPOINT OF HER CYCLE, THE FOLLICLE
WHICH ENCLOSES THE EGG IN ITS PROTECTIVE LAYERS, RUPTURES.
THIS IS OVULATION.
THE EGG TRAVELS THROUGH THE FALLOPIAN TUBE
WHICH CONNECTS THE OVARY AND THE UTERUS, OR WOMB.
IN THE TUBE, THE EGG WAITS FOR *** FROM THE FATHER
TO FERTILIZE IT.
THE FERTILIZED EGG
NOW WITH GENETIC MATERIAL FROM BOTH PARENTS
MOVES THROUGH THE TUBE TO THE UTERUS
WHERE IT ATTACHES ITSELF TO THE NUTRIENT-RICH LINING.
AND HERE, THE OVARY ITSELF.
IN CROSS-SECTION, STAINED BLUE FOR BETTER VISIBILITY
WE SEE THE HUNDREDS OF TINY EGG CELLS.
THIS ONE IS NEARLY MATURE
AND IS SURROUNDED BY ITS NUTRITIVE LAYERS.
WHEN IT IS FULLY DEVELOPED
THE FOLLICLE, WHICH ENCLOSES THE EGG, WILL SWELL, LIKE THIS ONE
WITH FLUID, THE LIQUOR FOLLICULAE.
INSIDE THE FOLLICLE
THE EGG AND ITS NUTRITIVE LAYERS FLOATS IN THIS WATER OF LIFE
WHICH HAS THE SAME SALT CONTENT AS THE SEA.
THE SWOLLEN FOLLICLE-- HERE ON THE LEFT--
IS THEN GENTLY BRUSHED BY THE SWAYING FIMBRIAE
THE OUTERMOST FRINGES OF THE FALLOPIAN TUBE.
THESE FRINGES ARE ACTIVATED BY THE HORMONES
JUST BEFORE OVULATION.
THEY SWEEP OVER THE SURFACE OF THE OVARY
SEARCHING FOR THE NEWLY RELEASED EGG.
AS OVULATION NEARS, THE FRINGES BECOME FILLED WITH BLOOD.
THE FOLLICLE AT THE CENTER IS ABOUT TO BURST.
DIRECTLY ABOVE THE WHITE REFLECTIONS
THE LIQUOR FOLLICULAE POURS OUT OF THE FOLLICLE.
CONCEALED SOMEWHERE WITHIN IT IS THE EGG.
THE FRINGES SEARCH FOR THE NEWLY RELEASED EGG.
IT LIES HERE
SURROUNDED BY A CLOUD OF ITS OWN NUTRITIVE CELLS.
IT IS ONLY THE SIZE OF A GRAIN OF SAND.
AT THE FAR RIGHT
THE EGG IS DRAWN INTO THE FALLOPIAN TUBE.
DEEP INSIDE THE EGG IS THE NUCLEUS OF NEW LIFE ITSELF.
THIS IS THE MOUTH OF THE FALLOPIAN TUBE.
ITS ALMOST IMPERCEPTIBLE MUSCLE CONTRACTIONS MOVE THE EGG ALONG
TOWARD THE UTERUS.
HERE THE EGG HAS REACHED THE INTERIOR OF THE TUBE ITSELF.
THESE MANY FOLDS OF TISSUE ARE LINED WITH TINY CILIA
WHICH MAINTAIN A CONSTANT, GENTLE MOTION
THAT DRAWS THE EGG ALONG ITS LENGTH.
THE INSIDE OF THE TUBE IS ACTUALLY ONLY
ABOUT TWICE THE THICKNESS OF A SINGLE HUMAN HAIR.
IT TAKES THE EGG THREE TO FOUR DAYS TO TRAVEL THIS DISTANCE
OF ONLY FIVE INCHES.
THE TRANSLUCENT EGG HERE LIES IN A MUSCLE FOLD
DEEP INSIDE THE FALLOPIAN TUBE.
ON THE DIAGONAL EDGE BELOW THE EGG
WE CAN SEE A THIN, SHIMMERING LAYER OF THE CILIA
WHICH LINE THE TUBE.
GENTLY MOVING THE EGG ALONG
THEY ARE EXACTLY LIKE THE CILIA OF THE PRIMITIVE PROTOZOA.
THE EGG MUST JOIN WITH A ***
WITHIN 24 HOURS OF LEAVING THE OVARY
FOR CONCEPTION TO TAKE PLACE.
IF NO *** ARE PRESENT, THE EGG DISINTEGRATES
AND THE SAME CYCLE WILL HAPPEN AGAIN THE FOLLOWING MONTH
AND THROUGHOUT ALL THE WOMAN'S CHILDBEARING YEARS.
THIS REMARKABLE CYCLE IS MADE POSSIBLE
BY COMPLEX MOLECULES, THE SEX HORMONES.
CRYSTALLIZED AND STAINED, THEY LOOK LIKE THIS.
HORMONES CONTROL A WOMAN'S ENTIRE REPRODUCTIVE CYCLE.
HORMONES CONTROL A MAN'S REPRODUCTIVE ABILITY, AS WELL.
ONLY SEVEN WEEKS AFTER CONCEPTION
THE FETAL SYSTEM IS PERMANENTLY SENSITIZED
TO BE MALE OR FEMALE BY THE SEX HORMONES.
ONE FETUS WILL DEVELOP OVARIES
AND ITS BRAIN WILL BE PROGRAMMED TO RELEASE HORMONES IN CYCLES.
IT IS FEMALE.
ANOTHER FETUS WILL DEVELOP TESTICLES
AND ITS BRAIN WILL RELEASE
CONSTANT LOW-LEVEL AMOUNTS OF SEX HORMONES.
IT IS MALE.
77 BILLION HUMAN BEINGS HAVE LIVED ON THIS PLANET.
FOUR BILLION LIVE HERE NOW.
AND EVERY YEAR, 128 MILLION NEW ONES ARE BORN.
WE HAVE ALREADY SEEN PART OF THE WOMAN'S REMARKABLE CONTRIBUTION
TO THIS UNENDING PROCESS.
NOW WE WILL EXPLORE THE MAN'S.
DURING A MAN'S LIFETIME
HIS TESTICLES PRODUCE BILLIONS OF ***.
THEY ARE STORED HERE IN THE EPIDIDYMIS.
THE COWPER'S GLAND PRODUCES A LUBRICATING FLUID
TO AID THE ***'S JOURNEY.
THE PROSTATE GLAND SECRETES AN ALKALINE FLUID
TO PROTECT THE ***.
TOGETHER, THEY PRODUCE MOST OF THE FLUID CALLED ***.
DURING ***, THE *** LEAVE THE EPIDIDYMIS
MOVING THROUGH THE VAS DEFERENS
THIS TUBE IN THE BODY CAVITY.
THEY APPROACH THE SEMINAL VESICLES
WHICH RELEASE A SOLUTION OF SUGAR TO NOURISH THEM.
COWPER'S AND PROSTATE FLUIDS COMBINE WITH THE ***
AND THE BLENDED *** CONTINUES OUT OF THE MAN'S BODY
THROUGH THE URETHRA IN THE ***.
THIS IS THE INTERIOR OF THE URETHRA ITSELF.
WE ARE TRAVELING UP INTO THE MAN'S BODY FROM THE OUTSIDE
THROUGH THE ***.
THE RED AREAS ARE BLOOD VESSELS.
THE BLACK SPOTS ARE CALCIUM DEPOSITS.
IN REALITY, THE JOURNEY IS ONLY SEVEN OR EIGHT INCHES LONG.
AHEAD, THE RED AREA IS THE OPENING TO THE BLADDER.
DURING *** AROUSAL
A VALVE HERE STOPS URINE FROM ENTERING THE URETHRA.
THE VALVE IS NOW OPEN.
HERE, NEAR THE BLADDER
THE URETHRA PASSES THROUGH THE PROSTATE GLAND.
THE WALLS OF THE PROSTATE HAVE MORE THAN 30 ORIFICES LIKE THESE
WHICH SQUEEZE OUT PROSTATE FLUID
WHEN *** PASS THROUGH THE URETHRA.
IT IS ABOUT THE SIZE OF A GOLF BALL AND IT RESEMBLES A SPONGE.
INSIDE, IT IS FILLED WITH THE SMALL CAVITIES
WHICH PRODUCE THE FLUID.
THESE ARE THE TESTICLES, HIGHLY MAGNIFIED
AND WITHOUT THEIR USUAL PROTECTIVE POUCH.
UNLIKE THE OVARIES, THEIR COUNTERPART IN WOMEN
THE TESTICLES LIE OUTSIDE THE BODY CAVITY.
THEY ARE MADE UP OF THE TIGHTLY COILED SEMINIFEROUS TUBULES
WHICH HAVE A TOTAL LENGTH OF 700 FEET.
IN THE TUBULES, *** ARE PRODUCED
AT THE EXTRAORDINARY RATE OF 100 MILLION EVERY 24 HOURS.
IN THE TISSUE BETWEEN THE TUBULES
THE SEX HORMONE TESTOSTERONE IS PRODUCED.
THE TESTICLES ARE THE ESSENTIAL MALE ORGANS OF REPRODUCTION.
THEY FUNCTION WELL ONLY UNDER VERY SPECIFIC CONDITIONS.
ONE OF THESE SPECIFIC CONDITIONS IS TEMPERATURE.
*** ARE PRODUCED MOST EFFICIENTLY
AT SEVERAL DEGREES BELOW NORMAL BODY TEMPERATURE.
THESE IMAGES FROM A THERMAL CAMERA REVEAL
THE VARIOUS TEMPERATURE ZONES IN THE ***
THE POUCH OF SKIN IN WHICH THE TESTICLES ARE SUSPENDED.
THE WHITE AREAS ARE THE WARMEST AND THE GREEN ONES, THE COOLEST.
THE *** KEEPS THE TESTICLES AWAY FROM THE BODY'S HEAT.
THIS IS A CROSS-SECTION OF ONE OF THE TUBULES IN THE TESTICLES
STAINED BLUE AND MAGNIFIED 2,000 TIMES.
AT THE DENSE CENTER OF THE TUBULE IS THE TRANSPORT CANAL
WHICH CARRIES MATURE *** AWAY TO THE EPIDIDYMIS FOR STORAGE.
THE SMALLER COMPARTMENTS PRODUCE MANY NEW IMMATURE ***
EVERY 36 HOURS.
AS THE *** BECOME MORE MATURE
THEY MOVE CLOSER TO THE CENTRAL CANAL.
THE AVERAGE MAN PRODUCES OVER 400 BILLION ***
IN HIS REPRODUCTIVE LIFETIME.
THESE ***, MAGNIFIED 4,000 TIMES
HAVE BEEN IN PRODUCTION FOR APPROXIMATELY A MONTH.
THEY ARE TIGHTLY PACKED IN THE TUBULE WITHIN THE ***
THEIR HEADS AND TAILS INTERTWINED.
INSIDE THE DEVELOPING *** HEADS
THE NORMAL BODY CELL'S 46 CHROMOSOMES
HAVE BEEN REDUCED TO 23.
BUT THIS REDUCTION OF CHROMOSOMES
SO ESSENTIAL TO FUTURE REPRODUCTION OF THE SPECIES
PUTS THE *** IN MORTAL DANGER.
THE MAN'S BODY CONSIDERS THESE CELLS ENEMIES.
BUT THE *** ARE DEFENDED BY NURSE CELLS LIKE THIS ONE
AND THE LARGE CELL AT THE RIGHT.
THEY FORM SPECIAL PROTECTIVE BARRIERS
AROUND THE MATURING *** CELLS.
EACH NURSE CELL CARES FOR MANY *** AT A TIME.
THIS TENDRIL IS PART OF THE REMARKABLE COMMUNICATION NETWORK
WHICH CONNECTS EACH NURSE CELL
TO OVER 150 SEPARATE *** CELLS THROUGHOUT THE TUBULE.
THE TENDRILS ENABLE THE NURSE CELLS
TO FEED AND PROTECT THE MATURING ***
AND TO MOVE THEM CLOSER TO THE TRANSPORT CANAL.
THIS *** IS NEARLY MATURE.
DURING ITS DEVELOPMENT
IT HAS LAIN IN TOTAL PASSIVITY IN THE TUBULE
BEING PROTECTED AND NOURISHED BY THE NURSE CELL.
WHEN MATURE, LIKE THIS ONE
IT IS TRANSPORTED BY THE NURSE CELL TO THE EPIDIDYMIS.
MILLIONS OF *** ARE STORED IN THESE DENSELY PACKED TUBULES