S2 Anatomy Exam 2: Embryonic Period

Front 1

Period during which the conceptus is most likely to develop a major congenital malformation:

Back 1

During the embryonic period
(wks 3-8)

Front 2

What forms the neural tube?


What does the neural tube form?

Back 2

the lateral edges of the neural plate


large brain (cephalically) & the spinal cord (caudally)

Front 3

The neural folds are temporarily incomplete where

Back 3

At the cranial and caudal neurotropes (close at day 25 and day 27)

*eventually fuse to form neural tube

Front 4

What cells separated from the junction of the neural tube and surface ectoderm

Back 4

Neural crest cells

Front 5

When do the first somites appear

Back 5

Day 20

*from paraxial mesoderm (occipital region caudally)

Front 6

When does bone marrow become the definitive blood-forming organ?

Back 6

After the seventh month of gestation

Front 7

Formation of the placenta begins at the morula stage & the blastocyt consists of what ?

Back 7

inner cell mass (embryoblast)
^(will form embryo proper)
& outer cell mass (trophoblast)
^(will form fetal placenta)

Front 8

During the 2nd week of development the trophoblast differentiates into what 2 layers?

Back 8

synctiotrophoblast (outer multinucleated layer)
and
cytotrophoblast (inner cellular)

*eventually cytotrophoblast grows together w synctiotrophoblast

Front 9

What is the decidua reaction?

Back 9

endometrial cells around the conceptus become loaded with glycogen and lipids and the tissue becomes edematous

Front 10

Lacunae appear w/i the synctiotrophoblast as it invades the sinusoids of the endometrium, what does this establish?

Back 10

uteroplacental circulation

Front 11

The chorionic cavity develops w/i the extraembryonic mesoderm as the ______________ is pinched off

Back 11

secondary yolk sac

Front 12

The chorion remains attached to the amnion & yolk sac via the ___________

Back 12

connecting stalk

Front 13

The trophoblast continues to develop during the 3rd week w/ formation of the __________________

Back 13

outer cytotrophoblast shell

Front 14

Once villi form, the fetal and maternal circulation are only separated by what?

Back 14

"placental barrier"
(fetal capillary endothelium & synctiotrophoblast)

Front 15

What 2 components form the placenta?

Back 15

chorion frondosum (fetal portion)
decidua basalis (maternal component)

Front 16

What are the important functions of the placenta?

Back 16

-exchange of gases
-exchange of nutrients & electrolytes
-transmission of maternal antibodies
-production of hormones

Front 17

Ectoderm germ layer gives rise to what?

Back 17

CNS, PNS, sensory epithelium of the eye, nose, ear and epidermis of the skin, hair, nails and subcutaneous glands, pituitary gland and tooth enamel

Front 18

Where dpes the conotruncal septum of the hear come from?

Back 18

Neural crest cells

Front 19

What else do the neural crest cells make (derivatives)?

Back 19

Spinal and sensory ganlia of cranial nerves V, VII, IX, X, autonomic ganglia, adrenal medula, schwann cells, connective tissues of the anterior part of the skull and meninges, melanocytes, c cells of the thyroid gland

Front 20

What are the three parts of mesoderm?

Back 20

Paraxial, intermediate and lateral plate

Front 21

What does the sclerotome form?

Back 21

cartilage and bone of the axial skeleton, including vertebral column


*epimeric & hypomeric are skeletal-muscle forming regions

Front 22

What does the dorasl dermatome form?

Back 22

Forms the dermis of the skin

Front 23

What does the intermediate mesoderm form?

Back 23

Urogenital structures

Front 24

Lateral plate mesoderm diveds into what two layers?

Back 24

somatic/parietal and the splanchnic visceral layer

Front 25

The two layers formed by the mesoderm are separated by what?

Back 25

intraembryonic cavity

Front 26

Where does blood vessel formation occur?

Back 26

in mesoderm near yolk sac at 3 weeks then from lateral plate mesoderm

Front 27

What organ becomes the major hematopoietic organ of the fetus by week 6?

What does it do?

Back 27

Liver


sends stem cells to colonize bone marrow (definitive blood-forming organ)

Front 28

What are the three parts of the gastrointestinal tract?

Back 28

Cephalic foregut (buccopharyngeal to liver, the hindut (tail) and midgut (connected to yolk sac by the viteline duct)

Front 29

Where does the respiratory system come from?

Back 29

Lung bud….an outgrowth, respiratory diverticulum from the ventral wall of the foregut

Front 30

What else does the endodermal germ layer contribute to?

Back 30

Urinary bladder, urethra, thyroid and parathyroid glands, liver and pancreas, tonsils, thymus,llining of typanic cavity and auditory tube

Front 31

What do the synctiotrophoblasts do?

Back 31

erode the endometrium

Front 32

How is the uteroplacental circulation established?

Back 32

Lacunae in the synctiotrophoblast invade capillaries and make sinusoids and the flow of maternal blood forms

Front 33

Excess Amnionic fluid is called?

What might this lead to?

Back 33

polyhydramnios

-anencephaly or intestinal atresia which prevent swallowing & absorption respectively

Front 34

Deficient amnionic fluid?

What might this lead to?

Back 34

oligohydramnios

-renal agenesis or amnion rupture, resulting in clubfoot or lung hypoplasia

Front 35

What contributes to the umbilical cord coming out of the umbilical ring?

Back 35

Connecting stalk and the vitelline duct

Front 36

What are the two types of bone formation?

Back 36

Intramembranous abd endochondral

Front 37

Where do the intervevertebral discs form in the sclerotome?

Back 37

Between the the cephalic and caudal halves

Front 38

The formation of the CNS begins w/ the development of the ___________

Back 38

neural plate

Front 39

As part of face & anterior neck formation, neural crest cells migrate into _________________ & form CT

Back 39

pharyngeal arches

Front 40

During the embryonic period of development the age of the embryo is expressed by what?

Back 40

the number of somites

Front 41

Each somite divides into;
a ventromedial __________
a dorsomedial ___________
a dorsolateral ___________
and a dorsal ____________

Back 41

sclerotome (ventromedial)
dorsomedial (epimeric)
dorsolateral (hypomeric)
dermatome (dorsal)

Front 42

The intraembryonic cavity, lined by mesothelial/serous membrane, is later partitioned to form ________, __________, & _________ in the adult

Back 42

pericardial, pleural, and paritoneal cavity

Front 43

The endodermal germ layer has the ______________ as its main derivative, due to the lateral cephalocaudal folding of the trilaminar germ disc

Back 43

GI tract

Front 44

The fetal period (wk 9-birth), lasts from gestation until ___________ after fertilization or ____________ after last menstrual period

*main time of growth & functional maturation

Back 44

266 days (38 wks)
280 days (40 wks)

Front 45

When are primary ossification centers present?

Back 45

by 12th week

Front 46

What hormone does the synctiptrophobast secrete, during the first 2 months to maintain the corpus luteum?

Back 46

human chorionic gonadotropin (HCG)

Front 47

What hormones do the placenta produce by the 4th month?

Back 47

-progesterone, maintains pregnancy w/o corpus luteum
-estrogen, stimulates uterine growth & mammory development

Front 48

Occasionally strips of amnion tear away to form amniotic bands. What defect can this lead to?

Back 48

constriction or amputation of an extremity, or part of fetus

Front 49

What are the main functions of amniotic fluid?

Back 49

-shock absorption
-prevents embryonic adhesion to amnion
-allow fetal movement
-allow fetal growth
-provides barrier to infection
*may be collected & analyzed for amniocentesis