Embryology

Question 1

Nondisjunction

Answer 1

Uneven splitting in anaphase - leading cause of death

Question 2

Fertilization

Answer 2

The process of fusing a sperm and egg

Question 3

Capacitation

Answer 3

When the sperm has the ability to have direction, motility, and energy

Question 4

Barriers of egg the sperm must cross

Answer 4

Corona radiata (outer)
Zona pellucida (middle)
Egg plasma membrane

Question 5

2 reactions for fertilization

Answer 5

Acrosome - sperm getting through the barriers

Cortical - egg closing the gate

Question 6

Cleavage

Answer 6

When zygote undergoes mitosis inside the plasma membrane, reducing cell size

Question 7

Compaction

Answer 7

Outer cells flatten and inner cells differentiate forming morula (solid ball of cells)

Question 8

Blastogenesis

Answer 8

Blastocyst (hollowed morula) cell walls begin to differentiate

Question 9

First week

Answer 9

Cleavage, compaction, morula formation, implantation

Question 10

Second week

Answer 10

Week of twos
Trophoblast - cytotrophoblast, syncytial trophoblast = placenta
Inner cell mass - epiblast (amniotic cavity), hypoblast (yolk sac)

Question 11

Third week

Answer 11

Gastrulation - form 3 germ layers by mesenchymal epiblast cells flowing through the primitive streak

Question 12

Primitive streak components

Answer 12

Pit, groove, node

Question 13

Where are there no mesenchymal cells?

Answer 13

Buccopharyngeal membrane and cloacal membrane

Question 14

Fourth week

Answer 14

Nerulation- neural plate folds to form the neural tube

Question 15

Where is the notochord found and what does it do?

Answer 15

Mesoderm and it’s a SIGNALING MACHINE

Question 16

Three types of mesoderm

Answer 16

Paraxial (somites) - muscle, bone, and CT of most of body
Intermediate - urogenital system
Lateral - muscle of body wall, digestive tract, proximal part of limbs

Question 17

Two sets of body folding in planning

Answer 17

Lateral/transverse - endorsed and mesoderm closing both sides, forms placenta
Cephalocaudal - ectoderm closing neural tube (zipper)

Question 18

What is the order in which the neural tube closes?

Answer 18

Begins midway along neural plate
Cranial end closes first
Caudal end second (primitive streak at caudal end)

Question 19

Placodes

Answer 19

Thickening of ectodermal tissue that make CNS segmentation

Makes lens plac, otic plac, olfactory epithelium, ant pit, sens ganglion of CN

Question 20

Folding in week 3 and 4

Answer 20

Purse string constriction

Question 21

Endoderm derivatives

Answer 21

Digestive glands, endocrine glands, respiratory sys, liver, ant pit

Question 22

Pregenesis

Answer 22

1. Make primordial germ cells (sperm/egg)
2. Find a place to sequester cells and develop gonads (ovary/testes)
3. Increase number of cells (mitosis)
4. Gametogenesis (meiosis)