Histology - Pre-Embryonic - Reverse

Question 1

mitotic divisions that form cells called blastomeres

Answer 1

Cleavage

Question 2

tighter blastomere intercellular adhesion forms morula, results in the formation of an inner and outer cell mass.

Answer 2

Compaction

Question 3

uterine fluid pumped into morula forms blastocyst

Answer 3

Cavitation

Question 4

blastocyst hatches from the zona pellucida

Answer 4

Hatching

Question 5

blastocyst implants in endometrium of uterine wall

Answer 5

Implantation

Question 6

Mitotic nondisjunction during cleavage, generally less severe; e.g., mosaic Down syndrome

Answer 6

mosaicism

Question 7

gives rise to the embryo (inner cell mass)

Answer 7

embryoblast

Question 8

gives rise to the fetal placenta (outer cell mass). cytotrophoblast, syncytiotrophoblast, vascular lacunae

Answer 8

trophoblast

Question 9

end with embryoblast

Answer 9

Embryonic pole

Question 10

end opposite embryoblast

Answer 10

Abembryonic pole

Question 11

blastocyst hatches from zona pellucida (ZP prevents implantation)

Answer 11

Hatching

Question 12

trophoblast at embryonic pole invades the endometrium on DAY 6

Answer 12

Implantation

Question 13

1. Implantation completed: uteroplacental circulation is established 2. Bilaminar disc formed: embryoblast differentiates into 2-layered disc

Answer 13

Week 2: Events

Question 14

1. cytotrophoblast 2. syncytiotrophoblast (part of chorion)

Answer 14

trophoblast becomes:

Question 15

1. epiblast 2. hypoblast (form the fetus, amnion, and part of chorion)

Answer 15

Embryoblast becomes:

Question 16

mitotic cells that give rise to the syncytiotrophoblast.

Answer 16

Cytotrophoblast

Question 17

the epithelial covering of the highly vascular embryonic placental villi, which invades the wall of the uterus to establish nutrient circulation between the embryo and the mother. It forms the syncytium that erodes endometrium and its vessels.

Answer 17

Syncytiotrophoblast

Question 18

maternal blood

Answer 18

vascular lacunae

Question 19

nutrition from maternal blood 1. uteroplacental circulation 2. implantation bleeding

Answer 19

nutrition from uterine gland secretions give way to

Question 20

human chorionic gonadotropin (hCG) that maintains progesterone secretion in the ovaries to promote uterine blood flow that sustains embryonic and fetal growth. Linked to emesis gravidarum (morning sickness).

Answer 20

Syncytiotrophoblast secretes

Question 21

hCG serum level elevation at day 8

Answer 21

Pregagncy test dectects

Question 22

implantation outside of the uterine body, most commonly in the unterine tube - “tubal pregnancy” - 95%+ of ectopic prenancies in uterine tube.

Answer 22

Ectopic pregnancy

Question 23

implantation over or near the cervical opening (internal os), usually presents late in pregnancy

Answer 23

Placenta previa

Question 24

trophoblast implants, but embryoblast is absent/incomplete. May produce a benign tumor called a hydatidiform mole. Elevated hCG secretion.

Answer 24

Molar pregnancy

Question 25

malignant tumor of the trophoblast. Elevated hCG secretion.

Answer 25

Choriocarcinoma

Question 26

one of the membranes that exist during pregnancy between the developing fetus and mother, formed by extraembryonic mesoderm and the two layers of trophoblast and surrounds the embryo and other membranes. Chorionic villi emerge from the chorion, invade the endometrium, and allow transfer of nutrients from maternal blood to fetal blood.

Answer 26

Chorion

Question 27

the inner layer of the trophoblast. It is interior to the syncytiotrophoblast and external to the wall of the blastocyst in a developing embryo.

Answer 27

cytotrophoblast

Question 28

embryoblast undergoes lamination to form two layers, hypoblast and epiblast

Answer 28

Bilaminar disc

Question 29

cells divide/migrate to line the blastocyst cavity. blastocyst cavity becomes the primary (primitive) yolk sac.

Answer 29

Hypoblast

Question 30

a tissue type derived from the inner cell mass of the blastocyst. It lies above the hypoblast, and undergoes cavitation whereby the amniotic cavity (AC) is formed. It differentiates to form all three layers of the trilaminar germ disc (ectoderm, mesoderm, and endoderm) during gastrulation.

Answer 30

epiblast

Question 31

a short lived combination of hypoblast cells and extracellular matrix. At day 9-10 of embryonic development, cells from the hypoblast begin to migrate to the embryonic

Answer 31

exocoelomic membrane

Question 32

forms adjacent to the hypoblast, and spaces appear in it which unit to form the large chorionic cavity (CC).

Answer 32

Extraembryonic mesoderm (EM)

Question 33

"pinched off" from the pYS (primary yolk sac)

Answer 33

secondary (definitive) yolk sac (sYS)

Question 34

hypoblast cells which have migrated to line the blastocyst cavity. It later becomes secondary yolk sac after part of it is pinched off. Thereafter its remnants degenerates.

Answer 34

Primary yolk sac

Question 35

Zygote formed after fertilization in ampulla of uterine tube

Answer 35

Day 1

Question 36

Morula enters uterus

Answer 36

Day 4

Question 37

Implantation of blastocyst begins

Answer 37

Day 6

Question 38

Positive pregnancy test, detectable hCG levels.

Answer 38

Day 8

Question 39

1. Implantation completed (uteroplacental circulation established) 2. Bilaminar disc formed (hypoblast & epiblast appear).

Answer 39

End of Week 2

Question 40

Extraembryonic mesoderm + cytotrophoblast + syncytiotrophoblast

Answer 40

chorion =

Question 41

blastocyst cavity, embryoblast, trophoblast, embryonic/abembryonic poles

Answer 41

Blastocyst

Question 42

gastrulation, neuralation, body folding

Answer 42

Week 3 Events

Question 43

Loosely arranged, migratory. formed via epithelial-mesenchymal transformation at the primitive streak & node

Answer 43

mesenchymal cells

Question 44

sites of epiblast invagination. regress & degenerate at the end of week 4 when gastrulation completes.

Answer 44

Primitive streak and node

Question 45

head-tail axis

Answer 45

Cephalocaudal

Question 46

front-back axis

Answer 46

Ventral-dorsal

Question 47

Cephalocaudal, Ventral-dorsal, left-right

Answer 47

body axes

Question 48

future mouth

Answer 48

oropharyngeal membrane

Question 49

future anus

Answer 49

cloacal membrane

Question 50

structure which includes the transformation of the neural plate into the neural tube. induces formation of neural tube (future brain, spinal cord)

Answer 50

Neurulation

Question 51

failure of rostral neuropore to close

Answer 51

Anencephaly

Question 52

failure of caudal neuropore to close

Answer 52

Spina bifida

Question 53

Forms gut tube from endoderm and mesoderm around the secondary yolk sac. Also forms intraembryonic cavity.

Answer 53

Lateral body folding

Question 54

becomes thoracic and abdominopelvic cavities, froms during lateral body folding

Answer 54

intraembryonic cavity

Question 55

Relocates primitive mouth and heart to adult position, is driven by longitudinal growth of the neural tube

Answer 55

Cephalocaudal body folding

Question 56

helps the embryo exchange gases and handle liquid waste.

Answer 56

Allantois

Question 57

Tail regresses, limbs elongate & rotate, digits appear; face develops. Organogenesis. Greatest risk of birth defects in week 5.

Answer 57

Week 4 to 8

Question 58

gametes and epithelial cells lining digestive organs, respiratory airways, and some urogenital passages.

Answer 58

Endoderm

Question 59

epidermis & its derivatives (hair, nails, glands)

Answer 59

Surface Ectoderm

Question 60

neural tube gives rise to the brain and spinal cord.

Answer 60

Neuroectoderm

Question 61

differentiates into somites (somitomeres in head region), becomes dermis, skeletal muscle, vertebrae & ribs. lateral to (at the side of) the neural tube.

Answer 61

Paraxial Mesoderm

Question 62

urogenital system (majority)

Answer 62

Intermediate mesoderm

Question 63

CT of body wall & limbs

Answer 63

Lateral plate mesoderm (parietal layer)

Question 64

GI/respiratory organs (excelpt epithelial lining)

Answer 64

Lateral plate mesoderm (visceral layer)

Question 65

fluid rich ECM with multipotent mesenchymal cells

Answer 65

Mesenchyme

Question 66

bilaterally paired blocks of paraxial mesoderm that form along the anterior-posterior axis of the developing embryo. They give rise to sclerotome, myotome, dermatome for each body segment.

Answer 66

Somites

Question 67

cleveage, compaction, morula formed, cavitation, blastocyst formed, zona pellucida hatching, implantation initiated

Answer 67

Week 1 Cellular Events

Question 68

axial skeleton

Answer 68

sclerotome

Question 69

dermis

Answer 69

dermatome

Question 70

skeletal muscle

Answer 70

myotome