Early Embryo

Question 1

Primordial germ cells arise from

Answer 1

Cells lining the wall of the yolk sac

Question 2

Components of the indifferent Gonad

Answer 2

1. Primordial germ cells
2. Primary sex cords
3. Mesonephric (Wolffian) and the Paramesonephric (Mullerian) ducts

Question 3

What converts Indfferent Gonad to testes and male genital system

Answer 3

Testes-determining factor (TDF)

Testosterone

Mullerian-inhibiting factor (MIF)

Question 4

What encodes for TDF

Answer 4

Sry gene on short arm of Y chromosome

Question 5

What secretes MIF

Answer 5

Sertoli cells

Question 6

What occurs in Meiosis 1

Answer 6

1. Synapsis: pairing of 46 homologous chr
2. Crossing over: exchange of segments of DNA
3. Disjunction: separation of 46 homologous chr WITHOUT centromere-splitting

Question 7

Primary oocytes arrested the first time in

Answer 7

Prophase (diplotene) of meiosis 1

Question 8

Secondary oocyte becomes arrested the second time in

Answer 8

Metaphase of meiosis 2

Question 9

What must degenerate for implantation to occur

Answer 9

Zona pellucida

Question 10

Embryoblast differentiates into

Answer 10

Epiblast and hypoblast forming bilaminar embryonic disk

Question 11

What forms the amniotic cavity

Answer 11

Epiblast

Question 12

What makes the primary yolk sac

Answer 12

Hypoblast

Question 13

Where is the site of the future mouth

Answer 13

Prechordal plate

Question 14

How is the prechordal plate formed

Answer 14

fusion of epiblast and hypoblast

Question 15

Extraembryonic mesoderm derived from

Answer 15

Epiblast

Question 16

What are the 3 primary germ layers

Answer 16

Ectoderm

Mesoderm

Endoderm

Question 17

What process produces the 3 primary germ layers

Answer 17

Gastrulation

Question 18

Ectoderm forms

Answer 18

Neuroectoderm

Neural crest cells

Question 19

Mesoderm forms

Answer 19

Paraxial mesoderm (35 pairs of somites)

Intermediate mesoderm

lateral mesoderm

Question 20

Chordoma

Answer 20

tumor that arises from remnants of notochord

found either intracranially or in the sacral region

Question 21

Surface ectoderm develops into (10)

Answer 21

1. Epidermis
2. Hair
3. Nails
4. Inner ear
5. External ear
6. Enamel of teeth
7. Lens of eye
8. Ant. Pituitary
9. Parotid gland
10. Anal canal below pectinate line

Question 22

Neuroectoderm develops into

Answer 22

Neural tube

Question 23

Neural tube develops into (6)

Answer 23

1. CNS
2. Retina and optic N
3. Pineal gland
4. Neurohypophysis
5. Astrocytes
6. Oligodendrocytes

Question 24

Neural crest ectoderm develops into (10)

Answer 24

1. Adrenal medullah
2. Ganglia
3. Pigment cells
4. Schwann cells
5. Meninges (Pia and arachnoid)
6. Pharyngeal arch cartilage
7. Odontoblasts
8. Parafollicular (C) cells
9. Aorticopulmonary septum
10. Endocardial cushions

Question 25

Mesoderm develops into (11)

Answer 25

1. Muscles
2. CT
3. All serous membranes
4. Bone and cartilage
5. Blood, lymph, CVS
6. Adrenal cortex
7. Gonads and internal repro organs
8. Spleen
9. Kidney and ureter
10. Dura mater
11. Notochord (Nucleus pulposus)

Question 26

Endoderm forms epithelial lining of

Answer 26

1. GI track:
   
   1. Forgut
   2. Midgut
   3. Hindgut
2. Lower resp system:
   
   1. Larynx
   2. Trachea
   3. Bronchi
   4. Lung
3. Urinary
4. Paryngeal puches:
   
   1. Auditory tube and middle ear
   2. Palatine tonsils
   3. PTH glands
   4. Thymus

Question 27

Endoderm forms parenchyma of

Answer 27

1. Liver
2. Pancreas
3. Submandibular gland
4. Sublingual gland
5. Follicles of thyroid gland

Question 28

Yolk sac derivatives

Answer 28

Primordial germ cells

Early blood cells and blood vessels