fetal development

Question 1

Embryonic development

Answer 1

first eight weeks after fertilization or two thirds of the first trimester.
During this time, tremendous change takes place. Cells divide and become redistributed. Tissues and organs form, as do structures that support and nourish the developing embryo

Question 2

Fetal development

Answer 2

From ninth week till the end of pregnancy. During the fetal period, the body grows rapidly and organs begin to function and coordinate to form organ systems.

Question 3

Fertilization

Answer 3

When egg and the sperm meets and makes a 46 chromosome cell called zygote. The plasma membrane of the egg is surrounded by a thin, clear layer of protein and carbohydrates called the zona pellucida. This layer is then surrounded by jelly like layers of follicle cells that are loose, called the corona radiata. When sperm meets the corona radiata, the sperm’s enzyme containing acrosome release its contents.

Question 4

Cleavage

Answer 4

Cleavage is the multiplication of cells using mitosis but the ball of cells remain the same size. It starts within a few hours of cell and mainly happens in the fallopian tube.

Question 5

Morula

Answer 5

Its a solid ball of cells in about 16-32 cells and is in the fallopian tube.

Question 6

Blastocyst

Answer 6

Blastocyst is a fluid filled ball of cells with a layer of cells called trophoblast on its outside and a sac of cells called inner cell mass along with the fluid inside the blastocyst.
Trophoblast will develop into extra embryonic structures like the placenta, and umbilical cord.
Trophoblast will develop into chorion that will develop to form a part of the placenta.
The inner cell mass will develops into the embryo itself.

Question 7

Placenta

Answer 7

Placenta is a structure that provides nutrients and oxygen to, and removes wastes from , the developing offspring.

Question 8

Implantation

Answer 8

Between 5-7 days after fertilization the blastocyst attaches to the endometrium, with the inner cell mass positioned against the endometrium. The trophoblast cells secrete enzymes that digest some of the tissues and blood vessels of the endometrium, and the blastocyst slowly sinks into the uterine wall.
completed by 10-14 day.

Question 9

Human chorionic gonadotropin

Answer 9

When implantation occurs the trophoblast starts to secrete a hormone called hCG, it maintains the corpus luteum to keep on the secretion of estrogen and progesterone, maintaining endometrium and preventing menstruation. At its highest for about two months and slowly decreases by month 4. After the first trimester, placenta secretes sufficient estrogen and progesterone to maintain the lining of endometrium.