Embryo Exam I

Question 1

What is the definition of fertilization?

Answer 1

fusion of pronucleus (sperm) with pronucleus (ovum) to form zygote

Question 2

What is the site of fertilization?

Answer 2

ampulla of uterine tube

Question 3

What are the phases of fertilization?

Answer 3

capacitation, acrosomal reaction, penetration (of 3 layers), zona reaction (no one else can go inside)

Question 4

What layer helps the implanting blastocyst?

Answer 4

trophoblast cells

Question 5

What is the site of implantation?

Answer 5

in the posterior superior wall of uterus

Question 6

Describe the placental barrier in early pregnancy and late pregnancy.

Answer 6

Early-
syncytiotrophoblast (outermost layer near maternal blood)
cytotrophoblast (middle)
connective tissue then fetal endothelium

Late-
syncytiotrophoblast (outermost layer near maternal blood)
fetal endothelium

Question 7

Which layer of placental barrier disappears between early and late pregnancy? Why does the layer that remains, remain?

Answer 7

cytotrophoblast disappears

syncytiotrophoblast remains because produced HcG (keeping placenta lined)

Question 8

Describe gastrulation.

Answer 8

3rd week. 3 primary germ layers

ectoderm, endoderm, mesoderm (from epiblast)

Question 9

Describe the three germ layers.

Answer 9

ectoderm. mesoderm. endoderm.

Question 10

Describe ectoderm.

Answer 10

brain and spinal cord, sympathetic ganglia

epidermis, hair, nails, glands of skin

Question 11

Describe endoderm.

Answer 11

epithelial lining and glands of digestive and respiratory tracts

Question 12

Describe mesoderm.

Notochord-
Somite-
intermediate mesoderm-
lateral plate mesoderm (somatic mesoderm and splanchnic mesoderm)-

Answer 12

Notochord- nucleus pulposus of IV discs (future vert. column)

Somite- vertebrae and ribs, dermatome, dermis of dorsal body region, myotome -trunk and limb musculature

intermediate mesoderm- kidneys, gonads

lateral plate mesoderm (somatic mesoderm and splanchnic mesoderm)-
somatic- dermis of ventral body region, parietal serosa, connective tissues of limbs (bones, joints, ligaments)

splanchnic- wall of digestive and respiratory tracts (except epithelial lining) visceral serosa, heart, blood vessels

Question 13

What happens at week four?

Answer 13

four pharyngeal (branchial arches)

Question 14

CAP

Answer 14

Clefts = ectoderm
Arches= mesoderm
Pouches =endoderm

Question 15

At the golden arches, childen tend to…

Answer 15

Chew (1st) - V (trigeminal)
Smile (2nd) - VII (Facial) 
Stylish (3rd) - IX (Glossopharyngeal... stylopharyngeal)
Swallow (4th)
Speak (6th) -X (Vagus)

Question 16

What are the muscles of mastication?

Answer 16

temporal, masseter, medial and lateral pterygoids

Question 17

What is in the neumonic for pharyngeal pouches?

Answer 17

Ear, Tonsils, Bottom To Top
1- tympanic (middle ear) vaity, auditory (eustachian) tube,
2- palatine tonsils, tonsillar fossa
3- inferior parathyroid gland, thymus (comes out of tongue)
4- superior parathyroid gland ultimobranchial body (parafollicular cells of thyroid gland)

Question 18

What happens if the 2nd 3rd and 4th pharyngeal clefts are obliterated by overgrowth of 3nd arch and 4th arch toward each other forming a cervical sinus… if this persists what forms?

Answer 18

branchial cyst or fistula

Question 19

What must degenerate for blastocyst implantation to occur?

Answer 19

zona pellucida