Welcome to the World, Little One

The birds and the bees - a timeline

First Trimester - Initial Stages - Emotional Rollercoaster

The Moment - Fertilization - Week Three, Day One

It has happened! The intercourse of the two partners has led to a sperm cell penetrating and fusing with an egg's allele set to form a zygote.

First Divisions - The Morula - Week Four, Day Two-Five

The very first four cell divisions of the new genetically individual zygote have begun to occur, rapidly growing the mass from one to sixteen cells - called a morula (which means "small berry").

#It's Official - Implantation/Gastrulation - Week Four-Five

Congrats! The zygote has begun digging into the uterus where it will begin to grow. There is definitely a person in there. The new implanted mass called a blastocyst - and through the activation of CGA and CGB gene mRNA - it begins to emit a hormone called hCG.

hCG (or human chorionic gonadotrophin) deactivate the two genes located on chromosomes nine and six which are responsible for menstruation. This makes sure the growing blastocyst isn't ejected from the uterus, because that would be terribly anti-climactic.

Towards the end of week two, the baby has formed into a mass of cells called a gastrula, with three distinct layers (ectoderm/mesoderm/endoderm) which evolve to form every bodily system we have. This is also where the baby gets the cushioning amniotic sac, and the nourishing/blood cell producing yolk sac - both characteristic of nearly all growing vertebrates.

  • Ectoderm == nervous system/skin/hair/mammary&sweat glands/tooth enamel
  • Mesoderm == circulatory system/muscles/bones/cartilage
  • Endoderm == digestive tract/respiratory system/thyroid/pancreas/urinary tract
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Drumroll - First Heartbeats/Physical Developments - Six Weeks

As the child's heart begins to beat at 160 bpm (over twice adult speed), the nose, mouth, and ears begin to form. Small depressions in the side are where the arms are going to be. The baby is one quarter of an inch long.

Putting On the Leash - Umbilical Cord Forms - Seven Weeks

Feet and hands are slightly visible, tail is disappearing, and embryo is size of a blueberry

Power Button Green - First Neural Connections - Eight Weeks

Finally, inside the brain, the first couple neural passageways are formed - bringing the onset of the first brainwaves.

Awakening - Structure/Movement/Reflexes - Ten-Twelve Weeks

At ten weeks, the baby can bend their limbs and kick. The heart is formed in all its' glory, and other features such as teeth and gums have arrived. Also, the internal sex organs begin to form

The SOX9 gene from Hox1 gene pool produces transcription factors which activate mesenchyme multipotent stem cells in face and limbs to differentiate into chondrocytes, or cartilage tissue. After differentiation, the chondrocytes divide to form model for bones - after which they stop dividing and increase their volume drastically, which allows for calcification of the bones (or ossification). This more volumetric cartilage is called hypertrophic chondrocytes.

This scaffolding of cartilaginous bones holds the baby together until the cartilage can be ossified. This allows for the full range of movement in the baby.

The baby can move spontaneously and will react to outside stimuli by squirming. By this point, the baby is unmistakably human. At two inches long, the baby is fully formed and growing incredibly fast.

Second Trimester - 14 Weeks - Emotional Peace and Huge Development

Promiscuousness and Strengthening - Gender Revealed/Ossification Begins - Fifteen Weeks

By this time, the child has full maneuverability, can sense light, pee, be identified by fingerprints, and is around the size of an apple. If the picture is clear enough and the baby is turned the right way, ultrasound can figure out the gender of the baby.

The CBFA1 gene in the HoxA master gene web begins to produce transcription factors which cause mesenchyme multipotent stem cells and existing chondrocytes to differentiate and become osteoblasts - which are the builders of bone tissue. As well as the osteoblast creation, blood vessels begin invading the hypertrophic chondroblasts and kill them, making a blood-rich space which will then mature into bone marrow.

This is the activation of ossification - when the cartilage bone structure of the baby is now using ingested calcium from the mother to build real bones with working osteocytes. Around 250 milligrams a day is applied to the bone network.

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Morning Alarm - Hearing Achieved - Seventeen Weeks

Bookeeping - Formation of Myelin - Eighteen Weeks

Around the nerves, a protective layer consisting of a mixture of proteins and phospholipids called myelin is formed. This will continue for over a year after birth.

Definitely Shaggy - First Hairs - Nineteen Weeks

As well as lovely locks of hair, all sensory development in the baby's brain is rapidly increasing. The baby can hear the mother's voice.

Waking Up - Eyes Open - 20 Weeks

At this point, the baby's eyes (with eyelashes) may begin to blink, and although her vision is 20/400, she can sense the natural light filtering in through the womb. She is the size of a large eggplant, and her brain contains billions of neurons - all of which are still dividing.
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Third Trimester - 28 Weeks - Emotions Return and Rapid Weight Gain

Trash Bags - First Bowel Movement - 36 Weeks

A black mixture of early bodily fuzz and waxy outer covering called vernix casenosa is ingested by the baby as meiconium, and sent through the digestive tract where it is disposed, for the very first time, as feces.

At this time, the "early-term" baby may begin feeling the pressure of external cephalic version - which is a process used by doctors to urge the baby into a head-down position.

Ready to Go, but Preferably Not - "Full Term" - 39 Weeks

The baby is now fully developed and ready to be presented to the world. He/she weighs around seven pounds, or a small watermelon. Most of the temperature-controlling fat developed during the past trimester is done.

Welcome - Beginning of Labor/Birth - 40-41 Weeks

At this point, the weight of the baby is becoming individual to the baby, and labor could happen at any time. Finally, labor begins, and at the end, a physical human baby is its own worldly entity.

During labor, contractions of the female uterus force the baby out through the heavily stretched cervix and vagina. To allow this to happen, the baby's skull bones are soft and can shift around, sometimes causing a "coneheaded look" immediately after delivery.

Although labor is unimaginably painful, every mother makes the journey through it to have a baby in her arms. Occasionally, a painkiller called an epidural is injected into the mother if she cannot bear it naturally.

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Sources Cited

BabyCenter LLC. (2015). Inside Your Womb. Retrieved September 22-24, 2015, from http://www.babycenter.com/fetal-development-inside-your-womb

CBR Systems Inc. (2015). Ossification by Pregnancy Weekly. Retrieved September 23, 2015, from http://www.parentingweekly.com/pregnancy/fetal-development/ossification.htm

CK-12 Foundation. (2015). Human Egg Cells. Retrieved September 24, 2015, from http://www.ck12.org/life-science/Human-Egg-Cells-in-Life-Science/lesson/Human-Egg-Cells-Basic/

Gilbert, S. F. (2000). Osteogenesis: The Development of Bones. Retrieved September 23, 2015, from http://www.ncbi.nlm.nih.gov/books/NBK10056/

What to Expect Foundation. (2015, August 15). What to expect. Retrieved September 22-23, 2015, from http://www.whattoexpect.com/pregnancy/baby-bone-development/

Zimmermann, G., Ackermann, W., & Alexander, H. (2012, March 30). Result Filters. Retrieved September 22, 2015, from http://www.ncbi.nlm.nih.gov/pubmed/21832169