Development YO!

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Development YO!

• By
• Lil Stevie Kojack

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1 day post-ovulation

• The fertilization process takes about 24 hours.
• A sperm can survive for up to 48 hours.
• Though 300 million sperm may enter the upper part
  of the vagina, only 1, 3 million, enter the
  uterus.

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4 days post - ovulation

• About four days after fertilization, the morula
  enters the uterine cavity.
• Cells flatten and compact on the inside of the
  cavity while the zona pellucida remains the same
  size
• The presence of the blastocyst indicates that
  two cell types are forming the embryoblast, and
  the trophoblast.

4
13 days post-ovulation

• The yolk sac begins producing hematopoietic or
  non-nucleated blood cells.

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13 days post-ovulation Continued

• Chorionic villi "fingers" form in the "placenta"
  anchoring the embryo to the uterus. Blood vessels
  begin appearing first in the "placenta"
  surrounding the embryo.
• By the end of stage 6a, the embryo is attached to
  the developing placenta by a stalk later to
  become part of the umbilical cord

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19 - 21 days post-ovulation

• Looking at the embryo from the top, the head end
  is wider than the tail end, with a slightly
  narrowed middle.
• Every ridge, bump and recess now indicates
  cellular differentiation.
• A head fold rises on either side of the
  primitive streak. The primitive streak now runs
  between one-fourth to one-third of the length of
  the embryo.

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25- 27 days post-ovulation

• The embryo curves into a C shape.
• The arches that form the face and neck are now
  becoming evident under the enlarging forebrain.
• A blood system continues to develop.
• The beginning cells of the liver form before the
  rest of the digestive system.

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35 - 38 days post-ovulation

• As the brain has increased in size by one-third
  since the last stage, it is still larger than the
  trunk.
• Esophagus lengthens. Blood flow through the
  atrioventricular canal is divided into left and
  right streams, which continue through the outflow
  tract and aortic sac.
• The relative width of the trunk increases from
  the growth of the spinal ganglia, the muscular
  plate and the corresponding mesenchymal tissues.

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44 - 48 days post-ovulation

• Nerve plexuses (network of intersecting nerves)
  begin to develop in the region of the scalp. Eyes
  are pigmented and eyelids begin to develop and
  may fold.
• Kidneys begin to produce urine for the first
  time.

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44 - 48 days post-ovulation Continued

• The wrist is clearly visible and the hands
  already have ridges or notches indicating the
  future separation of the fingers and the thumbs.
• Ossification of the skeleton begins

11
53 - 54 days post-ovulation

• Eyes are well-developed, but are still located on
  the side of the embryonic head.
• Over the next few days, tongue development
  finishes.
• Feet approach each other, but are still
  fan-shaped and the toe digits are still webbed.

12
61- 68 days post-ovulation

• Basic brain structure of the fetus is complete
  and now the brain mass rapidly increases.
• Sockets for all twenty teeth are formed in the
  gum lines. Face has human appearance - one
  example is the nasolacrimal grooveforming on the
  upper lip.
• Vocal cords form in larynx and fetus can make
  sounds.
• Fingernails begin to grow from nail beds.

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61- 68 days post-ovulation Pic
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Fingerprints and toe prints begin.

• About 2.8 ounces (80g).
• Eyes are at final destination and face forward
  rather than to the sides and reflexes, such as
  blinking, develop. Ears move to final position
  and stand out from head.
• Fingertips and toes develop the unique swirls and
  creases of fingerprints and toe prints.
• Blood circulation is completely functional.

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Fingerprints and toe prints begin Pic
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Inner ear bones harden, hearing possible

• Bones of the ear - hammer, anvil and stirrup -
  harden, making sound conduction possible.
• Bones, muscles and organs are growing steadily.
• Blood vessels, bones and organs are visible
  underneath a thin layer of wrinkled, translucent,
  pink skin.

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Brain Surface Convolutions Begin

• Fetal brain's surface appears wrinkled.
• Rhythmic breathing and body temperature are now
  controlled by the brain.
• Production of red blood cells is entirely taken
  over by the bone marrow.
• Fetal body is two to three percent body fat.

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Brain Surface Convolutions Begin Pic
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Gastrointestinal system very immature.

• Gums now have ridges which may look like teeth.
  Head may now position (head-down) into pelvis
  getting ready for delivery.
• Gastrointestinal system is very immature and
  will not mature until three or fourth years after
  birth.
• Skin appears light pink because of blood vessels
  close to its surface.

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Gastrointestinal system very immature Pic
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Fetus now considered full term.

• Fifteen percent of body is fat, eighty percent of
  which is underneath the skin, the other twenty
  percent surrounds the organs.
• Fetal abdomen is large and round mainly due to
  the liver which is producing red blood cells.
• weight about 7.5 pounds (3.4kg)

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Fetus now considered full term Pic
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Resources

• http//www.visembryo.com/baby/index.html
• http//embryology.med.unsw.edu.au/wwwhuman/Stages/
  Stages.html