Embryology

Question 1

Define mutagen

Answer 1

Agent which causes genetic mutation

Question 2

Define teratogen

Answer 2

Agent/ factor which causes malformation of embryo

Question 3

Describe pregnancy periods

Answer 3

Weeks 0-3 -> conceptuous
Weeks 4-9 -> embryonic
Weeks 9-birth -> foetal

Question 4

In what time frame is it referred to as an embryo?

In what time frame is it referred to as a foetus?

Answer 4

Embryo - 3-9

Foetus - 9-birth

Question 5

Best word to describe a single celled organism AKA a fertilised ovum?

Answer 5

Zygote

Question 6

What are the stages of embryology

Answer 6

1. Gametogenesis
2. Fertilisation
3. Cleavage
4. Gastrulation
5. Formation of a body plan
6. Organgenesis

GAME TO FERTILISE if showing CLEAVAGE.
Stop for GAS before FORMING A PLAN of ORGANS

Question 7

What is gametogenesis?

Answer 7

Formation of gametes

Female - oocyte

Male - spermatozoa

Question 8

Describe the 4 stages of fertilisation

What is the role of cortical enzymes?

Answer 8

1. Sperm BIND with the zona pellucida
2. Sperm RELEASE acrosomal enzymes from head + DIGEST way into oocyte
3. FUSE sperm and oocyte plasma together
4. TRIGGERS release of cortical enzymes

Cause zona pellucida to harden -> no more sperm can enter into oocyte

Question 9

What must happen before implantation can occur?

Where is most common site of implantation

Answer 9

Shed zona pellucida

Anterior and posterior walls of uterus

Question 10

What is cleavage?

Does it occur before or after implantation?

How many days is average from fertilisation to implantation?

Answer 10

Period of rapid cell division

Before

~6days

Question 11

Describe the stages from zygote to blastocyst

How many days does it take to form a morula?

How many days does it take to form a blastocyst?

Answer 11

ZYGOTE - fertilised oocyte

-> divides and produces daughter cells

BLASTOMERES

-> 16+ blastomeres

MORULA (3-4 days)

-> formation of trophoblast and embryoblast (cavity and inner cell mass)

BLASTOCYST (4-5 days)

Question 12

When does a baby stop being referred to as an embryo and becomes.a foetus?

Answer 12

Embryo - fertilisation -> 8 weeks

Foetus - 9 weeks -> birth

Question 13

What kind of cells move through the primitive streak to form 3 primary layers?

By what timeframe has the primitive streak been formed?

Answer 13

Epiblast cells

Week 3

Question 14

Give examples of what endoderm, mesoderm and ectoderm make up

Answer 14

• V basic generalisation*

Endoderm - lining of organs

Mesoderm - muscles and skeleton

Ectoderm - nervous system and epidermis

Question 15

What is does the term induction mean (one of the primary processes in embryology)

Answer 15

Ability of one cell to cause another to differentiate

Question 16

When implanted the embryoblast becomes the epiblast and the hypoblast what 2 things to each of these go onto form?

Answer 16

Epiblast

• amniotic sac
• dorsal surface

(think EA sports and D,E..)

Hypoblast

• ventral surface
• primitive yolk sac

Question 17

The trophoblast when implanted becomes what two things?

Answer 17

Synctiotrophoblast (single multinuceulated cell)

Cytotrophoblast
made up of individual cells