Histology - Pre-Embryonic - Reverse Flashcards Preview

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Flashcards in Histology - Pre-Embryonic - Reverse Deck (70)
1

mitotic divisions that form cells called blastomeres

Cleavage

2

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

Compaction

3

uterine fluid pumped into morula forms blastocyst

Cavitation

4

blastocyst hatches from the zona pellucida

Hatching

5

blastocyst implants in endometrium of uterine wall

Implantation

6

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

mosaicism

7

gives rise to the embryo (inner cell mass)

embryoblast

8

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

trophoblast

9

end with embryoblast

Embryonic pole

10

end opposite embryoblast

Abembryonic pole

11

blastocyst hatches from zona pellucida (ZP prevents implantation)

Hatching

12

trophoblast at embryonic pole invades the endometrium on DAY 6

Implantation

13

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

Week 2: Events

14

1. cytotrophoblast 2. syncytiotrophoblast (part of chorion)

trophoblast becomes:

15

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

Embryoblast becomes:

16

mitotic cells that give rise to the syncytiotrophoblast.

Cytotrophoblast

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.

Syncytiotrophoblast

18

maternal blood

vascular lacunae

19

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

nutrition from uterine gland secretions give way to

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).

Syncytiotrophoblast secretes

21

hCG serum level elevation at day 8

Pregagncy test dectects

22

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

Ectopic pregnancy

23

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

Placenta previa

24

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

Molar pregnancy

25

malignant tumor of the trophoblast. Elevated hCG secretion.

Choriocarcinoma

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.

Chorion

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.

cytotrophoblast

28

embryoblast undergoes lamination to form two layers, hypoblast and epiblast

Bilaminar disc

29

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

Hypoblast

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.

epiblast

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

exocoelomic membrane

32

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

Extraembryonic mesoderm (EM)

33

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

secondary (definitive) yolk sac (sYS)

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.

Primary yolk sac

35

Zygote formed after fertilization in ampulla of uterine tube

Day 1

36

Morula enters uterus

Day 4

37

Implantation of blastocyst begins

Day 6

38

Positive pregnancy test, detectable hCG levels.

Day 8

39

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

End of Week 2

40

Extraembryonic mesoderm + cytotrophoblast + syncytiotrophoblast

chorion =

41

blastocyst cavity, embryoblast, trophoblast, embryonic/abembryonic poles

Blastocyst

42

gastrulation, neuralation, body folding

Week 3 Events

43

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

mesenchymal cells

44

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

Primitive streak and node

45

head-tail axis

Cephalocaudal

46

front-back axis

Ventral-dorsal

47

Cephalocaudal, Ventral-dorsal, left-right

body axes

48

future mouth

oropharyngeal membrane

49

future anus

cloacal membrane

50

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

Neurulation

51

failure of rostral neuropore to close

Anencephaly

52

failure of caudal neuropore to close

Spina bifida

53

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

Lateral body folding

54

becomes thoracic and abdominopelvic cavities, froms during lateral body folding

intraembryonic cavity

55

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

Cephalocaudal body folding

56

helps the embryo exchange gases and handle liquid waste.

Allantois

57

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

Week 4 to 8

58

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

Endoderm

59

epidermis & its derivatives (hair, nails, glands)

Surface Ectoderm

60

neural tube gives rise to the brain and spinal cord.

Neuroectoderm

61

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

Paraxial Mesoderm

62

urogenital system (majority)

Intermediate mesoderm

63

CT of body wall & limbs

Lateral plate mesoderm (parietal layer)

64

GI/respiratory organs (excelpt epithelial lining)

Lateral plate mesoderm (visceral layer)

65

fluid rich ECM with multipotent mesenchymal cells

Mesenchyme

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.

Somites

67

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

Week 1 Cellular Events

68

axial skeleton

sclerotome

69

dermis

dermatome

70

skeletal muscle

myotome