W1: Embryology

Question 1

Ooccyte

Answer 1

A haploid cell, containing only one copy of each chromosome. It develops in the ovary and remains viable in the Fallopian tube for 12 hrs (1/2) day. Site of implantation = Uterus

Question 2

Zona Pellucida

Answer 2

Thick extracellular matrix that surrounds the oocyte. Made of plasma membrane.

Question 3

Corona Radiata

Answer 3

Additional layers of cells that surround the oocyte (in addition to the zona pellucida).

Question 4

Zygote

Answer 4

Fertilized oocyte (by sperm). The nuclear fusion of 2 haploid cells into one diploid cell.

Question 5

Totipotent

Answer 5

Having the ability to give rise to all different cell types needed to make a human. Having “total potential”.

Question 6

Cleavage

Answer 6

A series of mitotic divisions by which the enormous volume of egg cytoplasm is divided into smaller cells.

Question 7

Blastomeres

Answer 7

Cells formed by cleavage.

Question 8

Morula

Answer 8

16-32 cell stage of zygote. A solid sphere of connected cells made of internal (embryo) and external cells (placentia).

Question 9

Compacted Morula

Answer 9

When the embryo differentiates into external and internal cells - each having different fates.

Question 10

Trophoblasts

Answer 10

External cells of the morula that will become the placenta.

Question 11

Blastocyst Cavity

Answer 11

The middle of the morula which fills iwth fluid from dividing trophoblasts.

Question 12

Inner Cell Mass

Answer 12

Internal compacted cells of the Blastocyst.

Question 13

Blastocyst

Answer 13

A morula with a central cavity filled with fluid. (Day 4 - 6- cells)

Question 14

Implantation

Answer 14

FIll

Question 15

What changes must occur in the zygote for fertilization to lead to development?

Answer 15

1) Meiosis II
2) Protein synthesis stimulated
3) Cytoplasm segregates to create polarity
4) DNA replication begins

Question 16

What is placenta derived from?

Answer 16

1) embryonic trophoblast

2) maternal endometrial cells

Question 17

Syncytium

Answer 17

Multinucleated mass that invades the uterine lining.

Question 18

What two layers do trophoblast cells proliferate into?

Answer 18

1) a layer that maintains cellular membranes around the embryo
2) syncytium

Question 19

Bilaminar Disc

Answer 19

2 sheets of cells derived from the inner cell mass of a morula form the 1) epiblast 2) hypoblast

Question 20

What does the epiblast of the bilaminar disc form?

Answer 20

epiblast (upper germ layer) > amniotic sac

Question 21

What does the hypoblast of the bilaminar disc form?

Answer 21

hypoblast (lower germ layer) > yolk sac

Question 22

Amniotic Sac

Answer 22

Filled with amniotic fluid that protects the embryo from physical injury

Question 23

Yolk Sac

Answer 23

Not an important food source

Question 24

Gastrulation

Answer 24

Process of the epiblast (of the bilaminar disc) turning into the 3 lipid bilayers.

Question 25

Primitive Streak

Answer 25

Raised groove that forms in the dorsal side of the epiblast that initiates gastrulation.

Question 26

Primitive Node

Answer 26

The end of the primitive streak.

Question 27

Mesoderm Formation

Answer 27

Changing from 2 to 3 layered disc. Epiblast cells move inward at the primitive streak. Initially displacing the hypoblast to form the endoderm and then the mesoderm.

Question 28

Ectoderm

Answer 28

Skin

Question 29

Endoderm

Answer 29

Digestive & respiratory

Question 30

Mesoderm

Answer 30

Muscle & bone

Question 31

Notochord

Answer 31

1) Defines the body axis or midline, dividing right from left 2) Induces the formation of the nervous system

Question 32

Neurulation

Answer 32

Events by which the notochord induces ectoderm cells to form the nervous system. 1) Ectoderm in dorsal midline thickens = neural plate 2) Edges of neural plate fold towards each other = neural folds 3) Neural folds meet dorsally and overly the ectoderm = neural tube

Question 33

Neural Tube

Answer 33

CNS

Question 34

Neural Crest

Answer 34

PNS

Question 35

Epidermis

Answer 35

Skin covering spine

Question 36

Spinal bifida

Answer 36

If closure of the neural tube is incomplete caudally.

Question 37

Mesoderm derivatives

Answer 37

1) notochord 2) somites 3) intermediate mesoderm 4) lateral mesoderm

Question 38

Transverse mesoderm differentiation:

Answer 38

Somites > sclerotome | lateral mesoderm > somatic and splanchnic portions

Question 39

Gut tube

Answer 39

The majority of the yolk sac that folds inside of the embryo.

Question 40

What are the 3 parts that somites divide into?

Answer 40

1) sclerotome > verberal column and ribs 2) myotome > limb and trunk muscles 3) dermatome > dermis

Question 41

What does the intermediate mesoderm give rise to?

Answer 41

kidneys & gonads

Question 42

What does the lateral mesoderm give rise to?

Answer 42

1) Splanchnic (visceral) mesoderm > membranes of viscera, heart, blood vessels 2) somatic (body) mesoderm > membranes that line the body cavity, coelom

Question 43

Foregut

Answer 43

``` Lung buds Mouth pharynx esophagus stomach part of small intestine ```

Question 44

Midgut

Answer 44

part of small intestine | 2/3 of large intestine

Question 45

Hindgut

Answer 45

large intestine rectum urogenital system