36.2.4 - Stages of development / oogensis

Question 1

Stages of Development

Answer 1

Fertilization
Cleavage
Gastrulation
Organogenesis

Question 2

1. Fertilization

(Slide 7)

Answer 2

Fusion of gametes Sperm and Egg

-Egg receives sperm on receptor

-Sperm release acrosome = enzymes to digest coat of egg

-Receptors on egg and sperm – fusion of membranes – sperm nucleolus enter egg

-Egg release enzymes and carbohydrates (exocytosis) = cortical reaction to prevent other sperm from entering

-If another sperm enters the egg dies due to an extra chromosome

Question 3

2. Cleavage

(Slide 8)

Answer 3

period of rapid cell division with little to no growth (1-2-4-8)

-Embryo travel to the oviduct

-Hatechs in the oviduct can cause explosions, killing the mother (must kill embryo) (Eptopic pregnancy)

-Hatches from the fertilization envelope

Human implantations occur at the end of the cleave stage but before gastrulation occurs

Question 4

3. Gastrulation
   (Slide 9)

Answer 4

Cell migrations and specifications of their embryonic tissues (ectoderm, mesoderm, endoderm)

-Ectoderm – Skin, nervous system

-Mesoderm – Muscles, Bones, Connective tissues, Organs (kidney)

-Endoderm – Digestive tract, associated organs (liver & pancreas)

Question 5

4. Organogenesis
   (Slide 10)

Answer 5

Formation of organs (most animals’ first organ nervous system) - if the nervous system cannot develop, that organism needs to fail

-Form from three germ layers: Ectoderm, Mesoderm, Endoderm

22-day human embryo

Folding of the nervous system

Question 6

Path of Egg -

Answer 6

Ovary - Ovaduct - Uterus - Implants and Developers