Embryology

Question 1

What week of embryogenesis does gastrulation occur?

Answer 1

2-3 weeks

Question 2

What week of embryogenesis does organogenesis occur?

Answer 2

3-8 weeks

Question 3

Cleavage

Answer 3

Day 1-3 ball of cells (blastomere) stays the same size with subsequent divisions
Cells are totipotent

Question 4

Compaction

Answer 4

Blastomere maximize their contact with each other

Forms Morula

Question 5

Blastocyst

Answer 5

Forms on day 4
Two cell lineages trophoblast and inner cell mass
Cavity is called blastocoel

Question 6

Zona Pellucida

Answer 6

Forms around day 5
Acts as barrier from other sperm
Acts as an immunological barrier
Holds the blastomeres together

Question 7

Two layers of the trophoblast

Answer 7

Synctiotrophoblast creates cavity in endometrium

Cytotrophoblast basal cells that nourish synctio

Question 8

Formation of bilaminar disc

Answer 8

Occurs around day 8
Create epiblast, hypoblast, amniotic cavity
Cells above the epiblast layer are called the amnioblast

Question 9

1st, 2nd and 3rd lineage decisions

Answer 9

1. Compaction forming blastocyst day 3
2. Formation of bilaminar disc epiblast and hypoblast cell lineages day 8
3. Formation of trilaminar germ disc week 3

Question 10

Complete implantation occurs around?

Answer 10

Week 3
Formation of villus capillaries
Transformation of connecting stalk into umbilical chord
Formation of functional placenta

Question 11

Primitive streak grows

Answer 11

Caudal to rostral

Question 12

Notochord grows

Answer 12

Rostral to caudal with regression of primitive streak.

Question 13

Major body axis are established vai

Answer 13

Gastrulation

Question 14

Formation of the primitive streak is facilitated by

Answer 14

Secretion of NODAL in the caudal portion of the epiblast cells
Secretion of NODAL inhibitor in the raustral portion of the hypoblast cells

Question 15

Differentiation

Answer 15

Subdivision of germ layers

Question 16

Morphogenesis

Answer 16

Closure of the body cavities

Question 17

Neural Tube Grows

Answer 17

On top of notochord in rostral to caudal fashion
Neural Plate
Neural Fold
Neural Tube

Question 18

Paraxial Mesoderm Forms

Answer 18

Somites

Question 19

Intermediate Mesoderm forms

Answer 19

urinary system and major portions of the reproductive system

Question 20

Somatic Mesoderm

Answer 20

Also called parietal mesoderm: dermis of the lateral and ventral body wall and limbs

Question 21

Visceral Mesoderm

Answer 21

Also called splanchnic mesoderm: muscular and connective tissue layers of the gut.

Question 22

Induction

Answer 22

Interactions between tissues lead to a change in the course of development of one or both tissues

Question 23

Malformations

Answer 23

Morphological defects of an organ

i.e. thalidamide babies

Question 24

Disruptions

Answer 24

Alteration of already formed structures by destructive processes
i.e. ring consriction of limbs caused by amniotic bands

Question 25

Deformations

Answer 25

abnormal form, shape or position of an organ by mechanical forces
i.e. club feet due to too little amniotic fluid

Question 26

Time period of highest risk of teratogenesis

Answer 26

5 weeks

Question 27

Syndrome

Answer 27

A well-characterized group of anomalies that occur together in a predictable manner presumably due to a single underlying etiology

Question 28

Association

Answer 28

a group of anomalies that occur more frequently together than by chance, but the cause is unknown

Question 29

Sequence

Answer 29

a group of related anomalies that stem from a single initial major anomaly that alters the development of related tissues.