Embryology - Unit 1 Structure And Development

Front 1

What does the blastocyst differentiate to?

Back 1

Trophoblast and inner cell mass

Front 2

What does the trophoblast differentiate to?

Back 2

Syncitiotrophoblast (digests into endometrium) and cytotrophoblast (surrounds entire structure)

Front 3

What does the inner cell mass differentiate to?

Back 3

Epiblast and hypoblast

Front 4

What does the hypoblast differentiate to?

Back 4

Yolk sac

Front 5

What does the epiblast differentiate to? (5)

Back 5

1) Ectoderm of amnion
2) Extraembryonic mesoderm
3) Embryonic ectoderm
4) Embryonic mesoderm
5) Embryonic endoderm

Front 6

What does the embryonic ectoderm differentiate to?

Back 6

1) Surface ectoderm Epidermis, hair, nails, cutaneous glands, enamel)
2) Neural tube (Brain, spinal cord)
3) Neural crest (many things)

Front 7

What does the embryonic endoderm differentiate to?

Back 7

GI tract, liver, gall bladder, pancras, lungs, urinary bladder

Front 8

What does the embryonic mesoderm differentiate to?

Back 8

1) Paraxial mesoderm
2) Intermediate mesoderm
3) Lateral plate mesoderm
4) Cardiogenic mesoderm

Front 9

What does the paraxial mesoderm differentiate to?

Back 9

Somites

Front 10

What does the intermediate mesoderm differentiate to?

Back 10

Urinary system and gonads

Front 11

What does the lateral plate mesoderm differentiate to?

Back 11

1) Somatic layer (sternum, limb bud - AER and ZPA)
2) Splanchnic layer (viscera, except lining)

Front 12

What does the surface ectoderm differentiate to?

Back 12

Epidermis, hair, nails, cutaneous glands, enamel

Front 13

What does the neural tube differentiate to?

Back 13

Brain, spinal cord

Front 14

Whatdoes the neural crest differentiate to?

Back 14

Many things

Front 15

What does the somatic layer of LPM differentiate to?

Back 15

Sternum, limb buds (remember apical epidermal ridge where proliferation occurs and zone of polarizing activity)

Front 16

What does splanchnic layer of LPM differentiate to?

Back 16

Viscera, except lining

Front 17

What do somites differentiate to?

Back 17

1) Sclerotome (vertebra, ribs)
2) Dermomyotome (muscles, dermis)

Front 18

What do sclerotomes differentiate to?

Back 18

1) Dorsal - vertebral posterior elements
2) Ventral - vertebral body
3) Lateral - ribs

Front 19

What do myotomes differentiate to?

Back 19

1) Epimere - dorsal (intrinsic back)
2) Hypomere - ventral (ventro-lateral trunk, limb muscles)

Front 20

What is caudal dysplasia and what causes it?

Back 20

- Failure of gastrulation to complete - mesodermal migration interrupted
- Varies from minor vertebral abnormalities to lower limb fusion
- Often caused by gestational diabetes

Front 21

What is siernomelia?

Back 21

Fusion of the lower limbs - form of caudal dysplasia

Front 22

What is a sacrococcygeal teratoma?

Back 22

Failure of the primitive streak to properly degenerate and end of gastrulation - contains many different tissue types

Front 23

What are two disorders of gastrulation?

Back 23

Caudal dysplasia and sacrococcygeal teratoma

Front 24

What are the main events during the first week of embryo development?

Back 24

Egg forms zygote -- morula -- blastocyst -- trophoblast and inner cell mass -- implantation occurs and ICM divides to epiblast and hypoblast

Front 25

What are main events during the second week of embryo development?

Back 25

1) Formation of bilaminar embryoblast
2) Differentiation and elaboration of extraembryonic membranes
3) Week of twos

Front 26

What are the main events of the third week of embryo development?

Back 26

1) Gastrulation - endoderm, mesoderm form from epiblast, notochord forms in mid-sagittal plane
2) Mesoderm divided into 4 groups
3) Neurolation begins

Front 27

What are the main events of the fourth week of embryo development?

Back 27

Lateral body folds, cranial body fold, caudal body fold - amnion now fully surrounds embryo

Front 28

What is hemivertebra?

Back 28

Failure of ossification center to form properly, or improper subdivision of somites/sclerotomes - one cause of scoliosis

Front 29

What is amelia?

Back 29

Congenital absence of a limb resulting from failure of limb outgrowth

Front 30

What is phocomelia?

Back 30

Acute, temporary failure of outgrowth - limb lacks intermediate elements but has distal elements

Front 31

What are two disorders of patterning?

Back 31

Polydactyly and tripphalangeal thumb

Front 32

What is polydactyly?

Back 32

Digit duplications

Front 33

What is synactyly?

Back 33

Fusion of adjacent skin - problem with programmed cell death