Embryology

Question 1

what process characterizes the transition from morula to blasocyst

Answer 1

water movement into the marula (ie cavitation) transforms the embryo into a blastocyte

Question 2

steps in fertilization

Answer 2

Question 3

what blocks polyspermy

Answer 3

cortical granules released from the egg

Question 4

blastomere vs blastocysts

Answer 4

blastomere is just another word for the cells of the developing embryo –> it takes a different name because the cells are totipotent (each one can form a complete embryo by itself)

Blastocyst –> what used to be the morula is now fluid filled and considered to be distinguished by having 2 zones: trophoblast (future placenta) and embyroblast

Question 5

T/F: all germ layers derive from the epiblast

Answer 5

TRUE

Question 6

when is the developing embryo most sensitive to teratogens

Answer 6

weeks 3-8

Question 7

what is this birth defect

Answer 7

sacrococcygeal teratoma

it is comon and consists of all tisue types because it developed from pluripotent stem cells

Question 8

what is this birth defect

Answer 8

Sirenomelia (mn: siren songs of mermaids)

aka caudal dysgenesis

caused by insuffficient mesoderm

Question 9

what is situs inversus?

Answer 9

a birth defects caused by dysfunction of the cilia around primitive node and there is a complete transposition of L/R axis…

serotonin (5HT) significant in determining the assymetry of organs following tthis and can cause comlete switch of viscera (including heart) in the thorax and abdomen.

Question 10

what is the likely diagnosis?

Answer 10

fetal alcohol syndrome

Question 11

Answer 11

B - anencephaly

Question 12

Answer 12

answer: B –> trophoblast

Question 13

what is the role of AER (apical epidermal ridges) in development of limbs?

Answer 13

forms a thickening at the distal end of lumb buds. Produces fibroblast growth factor (FGF) which interacts with underlying mesoderm to promote limb outgrowth.

Question 14

what are the possible complications of osteopetrosis

Answer 14

anemia, hepatosplenomegaly, immunodificencies, cranial neuropathies

Question 15

what are the known teratogens to cause limb and digit malformations

Answer 15

1. drugs
   
   1. valproate
   2. phentoin
   3. warfarin
2. toxins: cocaine, alcohol
3. maternal conditions
   
   1. gestational diabetes
   2. varicella zoster

Question 16

What muscle group derives from the epimere?

Answer 16

intrinsic muscles of the back

(all others derive from the hypomere)

Question 17

what is the condition?

Answer 17

chondroplasia (or pseudochondroplasia) activating mutation in FGFR3 (fibroblast growth factor) that impaired proliferation of cartilage in the growth plate leading to shorter long bones

Question 18

What is the first step in endochondral ossification?

Answer 18

artery invades the middle of cartilage

Question 19

What condition arises due to excessive growth hormone release after the growth plates have closed?

Answer 19

acromegaly

Question 20

T/F: only myotomes derive from mesoderm

Answer 20

FALSe

Question 21

Answer 21

All bones of the upper limb form from lateral plate
mesoderm that condenses along the central axis to
form the vasculature and skeletal components

Question 22

what are the only excepts to the rule that all muscles derive from mesoderm

Answer 22