Week 1

Question 1

What occurs with fertilization? (3)

Answer 1

• pronuclei

- zona pellucida

Question 2

zona pellucida

Answer 2

hick extracellular coat that surrounds all mammalian eggs and preimplantation embryos. The zona pellucida supports communication between oocytes and follicle cells during oogenesis; protects oocytes, eggs, and embryos during development, and regulates interactions between ovulated eggs and free-swimming sperm during and following fertilization.

Question 3

pro-nuclei

Answer 3

pair of gametic nuclei, in the stage following meiosis but before their fusion which will lead to the formation of the nucleus of the zygote.

Question 4

polar body

Answer 4

small haploid cell that is formed concomitantly as an egg cell during oogenesis, but which generally does not have the ability to be fertilized; byproducts of meiosis and have no biological role in fertilization or in embryo development.

Question 5

blastomere

Answer 5

cell formed from cleavage of initial cell formed from fertilization

Question 6

Day 1-5 of zygote formation

Answer 6

• 1: fertilization
• 2: cleavage-blastomeres formed
• 3: compaction- blastomeres form tight cell junctions, allows for passage of mRNA and proteins by individual cells
• 4: differentiation- some blastomeres move to inner part of cell while others stay on outside
• 5: cavitation: blastomeres on outside of cells now trophoblasts, inner cells become a mass, and a blastocoelic cavity created

Question 7

trophoblast

Answer 7

outer cells in blastula; supplies the embryo with nourishment and later forming the major part of the placenta.

Question 8

inner cell mass

Answer 8

will become the fetus

Question 9

morula

Answer 9

• solid ball of 10-30 cells resulting from division of a fertilized ovum, and from which a blastula is formed
• final stage prior to formation of a fluid filled cavity called the blastocoel cavity.

Question 10

hydatdiform mole

Answer 10

• molar pregnancy
• rare complication of pregnancy characterized by the abnormal growth of trophoblasts
• complete molar pregnancy: placental tissue is abnormal and swollen and appears to form fluid-filled cysts, no formation of fetal tissue.
• partial molar pregnancy: may be normal placental tissue along with abnormally forming placental tissue;may also be formation of a fetus, but the fetus is not able to survive

Question 11

Day 6

Answer 11

zona hatching- zona pellucida is shed

Question 12

Day 7

Answer 12

implantation- embryo implants into the uterus

Question 13

Day 9

Answer 13

cell mass differentiation- inner cell mast differentiates into hypoblast and epiblast

Question 14

Hypoblast

Answer 14

inner layer composed of cuboidal cells

Question 15

Epiblast

Answer 15

outer layer that consists of columnar cells

Question 16

Cause of hydatdiform mole

Answer 16

-result of fertilization between an enucleate egg and multiple sperm

Question 17

What forms the bilaminar disc?

Answer 17

Epiblast and Hypoblast

Question 18

Gastrulation

Answer 18

-process in which bilaminar disc forms trilaminar disc

Question 19

Primitive streak

Answer 19

• develops on day 15 of pregnancy
• thickened structure in epiblast near caudal end
• defines major axes of embryos body

Question 20

Primitive node

Answer 20

-develops from the primitive streak

Question 21

Primitive pit

Answer 21

-Circular depression in the primitive node that elongates toward the caudal end of the primitive streak

Question 22

Primitive pit

Answer 22

-Circular depression in the primitive node that elongates toward the caudal end of the primitive streak forming primitive groove

Question 23

Invagination

Answer 23

cells from the epiblast going through the primitive pit and invading space of hypoblast displacing and replacing its cells and creating the definitive endoderm

Question 24

Ectoderm

Answer 24

• Cells of the epiblast that did not invade space of hypoblast and are therefore on the outside of the definitive endoderm
• gives rise to nervous system and skin

Question 25

Mesoderm

Answer 25

• cells from epiblast that remain between the ectoderm and definitive endoderm
• gives rise to connective tissue

Question 26

Endoderm

Answer 26

• comes from cells of epiblast that replaced hypoblast during invagination through the primitive pit
• gives rise to lining of the airways and gastro intestinal tract

Question 27

Notochord

• comes from
• will form
• importance, secretion

Answer 27

• part of mesoderm
• will become nucleus pulposus of IV discs
• induces neurulation, secretes sonic hedgehog

Question 28

Neurulation

Answer 28

• Lateral edges of ectoderm will fold in forming two neural folds with a neural groove in the middle– the folds will continue until they meet and pinch the groove off into a closed off tube (neural tube); the open ends of the ectoderm will then begin to move around the mesoderm and endoderm until they meet on the other side and envelop the other two layers
• Reorganization of germ layers, outter to inner is ecto, meso, endo–with endo being smallest

Question 29

Neural plate

Answer 29

-neural folds and groove

Question 30

Neural tube

Answer 30

-formed from the neural folds growing towards each other and pinching off, making the neural groove a closed off tube

Question 31

Neural crest

Answer 31

-pieces of the ectoderm from neural tube that migrate and give rise to PNS and cranial nerves

Question 32

What factor induces neural crest formation?

-transcriptor factor

Answer 32

• WNT pathway

- Gbx2

Question 33

Chordoma

Answer 33

-Vestigial remanence of notochord; tumor derived from notochord

Question 34

Somatogenesis

Answer 34

• formation of somites
• Dermatome: becomes skin (dermis)
• Myotome: becomes skeletal muscle
• Syndotome: becomes tendons
• Sclerotome: becomes vertebral column