The embryonic period

Question 1

what is gastrulation

Answer 1

process that establishes the three primary germ layers, forming a trilaminar embryonic disk

Question 2

define chordoma

Answer 2

benign or malignant tumor that arises from remnants of the notochord (found either intracranially or in sacral regions)

Question 3

what is hCG (human chorionic gonadotropin)

Answer 3

glycoprotein hormone that stimulates the production of progesterone by the corpus luteum

Question 4

what is human placental Lactogen (hPL)

Answer 4

protein hormone that induces lipolysis, elevating free fatty acid levels in the mother (growth hormone of the fetus)

Question 5

how is amniotic fluid reabsorbed?

Answer 5

swallowing, absorption through GI tract, or excess is passed into maternal blood

Question 6

define neurulation

Answer 6

formation and closure of the neural tube

Question 7

what does Hox (Homeobox complex) do?

Answer 7

controls the basic segmentation of the human embryo in a craniocaudal direction during the embryonic period

Question 8

what are the 2 layers in the embryo

Answer 8

epiblast & hypoblast

Question 9

what are the 2 layers in the trophoblast

Answer 9

syncytiotrophoblast & cytotrophoblast

Question 10

what is the extra embryonic (XE) Mesoderm derived from

Answer 10

epiblast (& yolk sac)

Question 11

where is the extra embryonic mesoderm found

Answer 11

between the inner lining of the cytotrophoblast and yolk sac

Question 12

what kind of support does the XE mesoderm give

Answer 12

mechanical and trophic

Question 13

what is the fetal contribution to the placenta

Answer 13

chorion

Question 14

what can a pregnancy ultrasound done in the 1st trimester do:

Answer 14

confirm normal pregnancy
determine the baby's age
look for problems
determine the baby's heart rate
look for multiple pregnancies (i.e. twins)

Question 15

what major events occur during the embryonic period

Answer 15

all major body systems develop
2D disk to 3D cylinder
Folding of the embryo
Craniocaudal folding-CNS
Lateral Folding-amnion/body wall

Question 16

what is gastrulation the beginning of

Answer 16

morphogenesis

Question 17

what are the three germ layers

Answer 17

endoderm, mesoderm, ectoderm

Question 18

what is the primitive streak

Answer 18

future axis of embryo

Question 19

what are all primary germ layers derived from

Answer 19

epiblast

Question 20

what is the course for embryonic tissues starting with the fertilized egg

Answer 20

fertilized egg-> blastocyst-> inner cell mass
from inner cell mass it can go to either hypoblast or epiblast
hypoblast-> extraembryonic endoderm-> yolk sac (ends here)
epiblast-> either amniotic ectoderm (ends there) or primitive ectoderm
primitive ectoderm-> primitive streak (then to embryonic endoderm and mesoderm) or straight to embryonic ectoderm

Question 21

what is caudal dysplasia

Answer 21

Germ layer disorder where there is a total or partial failure of development of the lower vertebrae, including the sacrum, which results in associated abnormalities of the lower extremities, spine, kidneys, GI and Genitourinary tracts

Question 22

what is caudal dysplasia caused by

Answer 22

abnormal gastrulation (mesoderm migration is disrupted)

Question 23

what is the primitive streak replaced by

Answer 23

notochord

Question 24

what are the functions of the notochord

Answer 24

structures- acts as rigid axis around which the embryo develops
skeletal- foundation upon which the vertebral column will form
Forms part of the intervertebral disks
Induction- will bring about formation of the neural tube

Question 25

what does chroma originate from

Answer 25

develops from remnants of embryonic notochord

Question 26

what functions as the primary inductor in the early embryo

Answer 26

notochord

Question 27

what is Piebaldism

Answer 27

disorder characterized by a congenital white forelock and multiple symmetrical hypo pigmented or depigmented areas

Question 28

what is Vitiligo

Answer 28

it is a disorder characterized by the loss of melanocytes and is considered an autoimmune disorder

Question 29

what is the forebrain considered at 4 weeks

Answer 29

prosencephalon

Question 30

what is the midbrain considered at 4 weeks

Answer 30

mesencephalon

Question 31

what is the hindbrain considered at 4 weeks

Answer 31

Rhombencephalon

Question 32

what are common characteristics of iniencephaly

Answer 32

extreme retroflexion of the head short and almost absent neck hyperextended spine facial skin is connected directly to the skin of the chest; the scalp is directly connected to the skin of the back

Question 33

what is spina bifida

Answer 33

failure of neural arches to form

Question 34

what is S.b. occulta

Answer 34

archest absent, tube is normal

Question 35

what is S.b. meningocele

Answer 35

dura and arachnoid also protude

Question 36

how is it hypothesized that folic acid prevents neural tube defects

Answer 36

disorders linked transformation of homocysteine to methionine (increased homocysteine elves appear to prevent the closure of the neural tube)

Question 37

Explain the development of the amnion

Answer 37

It is a thin protective membraned that develops from the epiblast Initially, the amnion overlies only the bilaminar embryonic disk (as the embryo grows it eventually surrounds the entire embryo creating the amniotic cavity) Then, the amniotic cavity becomes filled with the amniotic fluid Amniotic fluid protects the developing fetus and can be examined in a procedure (amniocentesis)

Question 38

explain the development of the yolk sac

Answer 38

The hypoblast cells migrate and become the exocoelomic membrane The hypoblast and the exocoelomic membrane form the yolk sac

Question 39

Describe Valamentous Placenta

Answer 39

occurs when the umbilical (fetal) blood vessels abnormally travel the amniochorionic membrane before reaching the placenta proper

Question 40

describe Placenta previa

Answer 40

occurs when the placenta attaches in the lower part of the uterus, covering the internal os * placenta blocks cervical opening * classic of 3rd trimester bleeding

Question 41

what are the risk factors for placenta accreta/increta/percreta

Answer 41

curettages, previous C-section, severe endometritis, or closely spaced pregnancies

Question 42

describe plreeclampsia and eclampsia

Answer 42

preeclampsia= sudden development of maternal hypertension involves a generalized arteriolar constriction that impacts the brain, kidneys, liver and small blood vessels treatment involves magnesium sulfate and hydrazine risk factors: nulliparity, diabetes, hypertension, renal disease, twin gestation, hydatidiform mole Eclampsia is the same but includes the symptom of convulsions

Question 43

what are the events of neurulation

Answer 43

1. notochord induced the overlying ectoderm to differentiate into the neuroectoderm and form the neural plate 2. neural plate folds to give rise to the neural tube 3. as neural plate folds, some cells differentiate into neural crest cells and form column of cells along both sides of the neural tube 4. the rostral part of the neural tubes become the adult brain 5. the caudal part of the neural tubes become the adult spinal chord 6. the lumen of the neural tube gives rise to the ventricular system of the brain and central canal of the spinal cord