Development of a Human Fetus
For my report I researched the development of a human embryo. I will take you through month by month. Three stages are commonly used to divide up the pregnancy. They are called trimesters. Every three months is a new trimester. I will now start off when the two parents "mate".
The Beginning
The male's sperm cell will meet the egg cell of the female. From now until birth the embryo will develop in the female. The sperm cell will force it's way into the egg cell and forming a zygote. This is considered the moment of conception or when all of the child's traits are decided and the sex of the child is decided. Now the child is just a single cell and starts growing in the womb.
First Month
The embryo is only 1 cm. long but already it is budding a head, arms, legs , eyes, and a nose. The heart has appeared but the brain and spinal cord are still just developing. The womb is now full with liquid and umbilicus and placenta are both being made. To get oxygen and get food it makes a skin called amnion. The amnion filters the liquids in the womb to get both the food and the oxygen it needs to survive. At the end of the first month the embryo has gone from 1cell to 10,000 cells and is still growing! In the next few month it will undergo many changes so read on!
Second Month
By now the embryo is 7-8 cm. long and about 14 grams. It's heart is finished and beating at a steady 65 beats a minute. The skeleton of the embryo is of soft gristle and won't ossify for another month. It now has arms , legs, feet, fingers, toes, and is starting to grow nails on it's fingers and toes! All the main organs are developed such as the stomach, liver, intestines, lungs, kidneys, and bladder.
Third Month
Now the embryo is 9 cm. long and 28 grams. The back of the embryo is straightening. The nervous system has been made and the embryo can feel and move. It's bones have ossified and it is getting it's first teeth buds. It is also getting eyelids although he still doesn't have eyes! The embryo is now a recognizable human.
Fourth Month
At the fourth month the embryo is 10- 12 cm. long and 110 grams. The embryo's head is bent down , legs crossed , knees tucked up , and arms folded. This is also called the fetal position. It has eyebrows but it still can't open it's eyes. The embryo gets small hairs all over called lanugo but will soon just disappear! No one knows why this happens but it it is said to remind us of our ape ancestors. It's skin is covered with a film called vernix caseosa that will waterproof the embryo's skin. By now the mother is starting to feel the embryo moving inside her and will continue to for the rest of her pregnancy.
Fifth Month
In this stage the embryo is 30 cm. long and 475 grams. During this month it will go through a growth spurt though not much else happens during this month.
Sixth Month
The embryo now is 35 cm. long and 500 grams. It gets it's second set of teeth buds. The embryo likes to move around a lot now but will soon slow down because of lack of room.
Seventh Month
It is 38 cm. long and 1500 grams. The embryo's arms and legs are skinny because it doesn't have a lot of muscles or fat. It still has lanugo and a big head compared to it's body. By this time the child would be able to breath and be born if in a emergency.
Eighth Month
The child is 45 cm. long and 2500 grams up untill now the embryo has had lanugo , red skin , and rough skin. Now though, it's skin is smooth, white or black, and it sheds it's lanugo. The lanugo is gone but it is getting head hair.The child is quiet now because it doesn't have any room left in the womb. It's arms are folded and it's knees are tuck up. The child's mother is supplying the child with antibodies to fight off some diseases. The baby is now getting ready to be born(breech or normal position).The fingernails are growing fast and may need a trim when it is born.
Ninth Month
The child is 50 cm. long and 3000 grams. The baby has bluish eyes and will stay that way until it is born. It is gaining weight for when it is born.
Now the child will be born and grow up. I hope you know more about a human embryo's development , after all we are