bio fertilization notes

43.3: How does Animal Development Proceed?

Amphibians are usually studied bc they can breed whenever, produce many large eggs and the embryos are in the water (easily observable)

Cleavage of the Zygote Begins Development

A: Zygote, fertilization occurs
B: (2) Cell undergoes mitosis
C: (4) Cell undergoes meiosis
D: Morula forms- Cell division is continued an \n internal cavity produces in the blastula
E: Blastula forms in the blogosphere, letting \n gastrulation begin
F: Gastrula creation begins
G: Gastrula is created, 3 tissue layered embryo
X: Embryo, final result

note: cleavage of the zygote begins development

Human Development- Cell differentiation, gastrulation + organogenesis in 2 months

Fertilization of human egg happens in uterine tube→ The zygote that comes from result will undergo a few cleavage divisions becoming a morula
Cells of inner cell mass have the potential to develop into any tissue type in the human body
- Also source of human embryonic stem cells
Cells of inner cell mass of an early blastocyst start to differentiate through induction
Amniotic egg includes 4 extraembryonic membranes especially the yolk sac
Gastrulation occurs after implantation
Inner cell mass grows and splits- 2 fluid-filled sacs are separated by the embryonic disk
- One layer of cells is continuous with yolk sac and other layer is continuous with amion
3rd week- Embryo forms the spinal cord and brain. Umbilical cord forms from fusion of yolk stalk and body stalk.
Body stalk contains allantois which contributes the blood vessels that will become umbilical arteries and vein. Umbilical cord will now connect embryo to placenta
4th and 5th wheels embryo kind of looks like a fish with the tail and rooves- 7th week they have eyes and fast developing brain
After two months the embryo is recognizably human
The child is now called a fetus
Their organs are very sensitive to toxic substances so mothers be aware
Growth and development continue during the last 7 months

\n In the next 5-7 Days: