Embryo

Question 1

Developing embryo consists of?

Answer 1

Embryoblast- epiblast, hypoblast

Trophoblast and Syncytiotrophoblast

Question 2

What happens day 16 of development?

Answer 2

Gastrulation which forms trilaminar embryo

Ectoderm, mesoderm, endoderm

Question 3

Neurulation

Answer 3

Neural groove forms neural tube by folding ectoderm and causes subdivision of mesoderm - Paraxial, intermediate, lateral plate

Question 4

What does the paraxial mesoderm form?

Answer 4

Formation of somitomeres that form the somites

Question 5

How many somites in each segment?

Answer 5

4 occipital
8 cervical
12 thoracic
5 lumbar
5 sacral
8-10 coccygeal

Question 6

What do the somites differentiate into?

Answer 6

Sclerotomes (gives rise to cartilage and bone) and dermomyotomes (skin and muscle)

Question 7

Poland Annomily

Answer 7

Lack of formation of Pec major/minormuscles

Question 8

Prune Belly

Answer 8

Missing hypaxial muscle that forms abdominal muscles

Question 9

Spina Bifida Oculta

Answer 9

Vertebral arch not fusing properly

Question 10

Congenital Anomalies of Vertebrae

Answer 10

Congenital Scoliosis
Accessory ribs
Fused ribs

Question 11

Klippel-Feil Anomaly (Brevicollis)

Answer 11

short neck due to absence or fusion of cervical vertebrae

Question 12

Limb Buds

Answer 12

Upperlimb buds appear Day 26 and lower limb buds appear Day 28

Question 13

Mesenchyme

Answer 13

Somatic layer of lateral plate mesoderm covered in layer of ectoderm and contributes to formation of all tissue except muscles

Question 14

Hox Genes

Answer 14

Regulate axis and patterning of somites

Question 15

Apical Ectodermal Ridge

Answer 15

Apex of each limb thickens to form AER which causes distal growth of limb and prevents mesechymal cells fro differentiating (progress zone)

Question 16

Zone of Polarizing Activity (ZPA)

Answer 16

Area or anterior/posterior growth that is regulated by retinoic acid (vitamin A) signaling Sonic Hedgehog Gene

Question 17

Why is acne medicine not given to pregnancy?

Answer 17

Acne may cointain retinoic acid and causedearly activation of SHH gene leading to mirror image limbs

Question 18

AER and Apoptosis

Answer 18

AER causes apoptosis in ridges that separate digits

Question 19

Bone formation

Answer 19

Mesenchymal cells condense into chondrocytes, hypertrophy of chondrocytes and death allows blood vessels to enter, osteoblasts migrate and form bone on top of chondrocytes

Question 20

Rotation of Limbs

Answer 20

Upper limbs rotate laterally 90 degrees

Lower limbs rotate medially 90 degrees

Question 21

Thalidomine

Answer 21

Used to treat morning sickness but caused limb malformation in developing fetuses

Question 22

Amelia

Answer 22

absence of an entire limb

Question 23

Meromelia

Answer 23

absence of part of limb

Question 24

Ectrodactyly

Answer 24

Cleft hand or foot- lobster claw

Failure of digital rays to form

Question 25

Brachydactyly

Answer 25

Shortness of digits

Question 26

Polydactyly

Answer 26

Extra digits

Question 27

Syndactyly

Answer 27

Webbed digits or fused digits

Question 28

Congenital Clubfoot

Answer 28

Defect involving the talus, prevents normal weight bearing