9-1: 10/24: Embryology Condensed

Front 1

Fertilization occurs in the ______ of the fallopian tube.

Back 1

Ampulla

Front 2

Morula

Back 2

12-32 cells in zygote (after blastula); begins to develop inner cell layer

Front 3

Blastocyst

Back 3

After morula enters uterus; formation of fluid-filled space (blastocele) inside morula

Outer cell layer = trophoblast (forms embryonic part of placenta)

Inner cell mass (embryoblast): becomes epiblast, endoderm

Front 4

Cyntotrophoblast vs Syncytiotrophoblast

Back 4

When trophoblast contacts endometrium, immediately differentiates into cytotrophoblast (INNER) and syncytiotrophoblast (multinuc'd without cell boundaries; OUTER)

Cytotrophoblasts are MITOTICALLY active; generate cells that migrate into syncytiotrophoblast (where they lose cell membranes)

Syncytiotrophoblasts makes contact with endometrium!

Front 5

Summarize week 1 of embryonal development.

Back 5

Zygote
Two-cell-->four-cell-->8-cell
Morula (mullberry)
Blastocysts
Attachment!

Front 6

Implantation is completed by _____.

Back 6

End of second week (usually on superior body of uterus)

Front 7

hCG is produced by ______.

What is the function of hCG?

Back 7

hCG produced by syncytriotrophoblast

Fn:
Antigonadotropin (inhibits LH, FSH to prevent ovulation)

Steroidogenic: stimulates PG production by corpus luteum

Front 8

Embryonic Disc
Epiblast vs Hypoblast

Back 8

Transformatino of embryoblast results in flat plate of cells: embryonic disc

Epiblast: Dorsal, floor of amniotic cavity

Hypoblast (primitive endoderm): ventral; roof of exocoelomic cavity

Front 9

Fate of epiblast.

Back 9

Becomes fetus proper

Front 10

Fate of primitive endoderm.

Back 10

Primitive endoderm = hypoblast

Will become yolk sac, fetal membranes

Front 11

Fate of trophectoderm.

Back 11

Most of fetal contribution to placenta

Front 12

Lacunae are present in ________.

Role?

Back 12

Lacunae are present in syncytiotrophoblast and establish primordial uteroplacental circulation

Front 13

Summarize the events of week 2 of embryogenesis.

Back 13

Completion of implantation

Formation of bilaminar embryonic disc (composed of epiblast and hypoblast; source of germ layers that form all tissues/organs)

Formation of extraembryonic structures: amniotic cavity, amnion, umbilical vesicle (yolk sac), connecting stalk, chorionic sac

Front 14

What is gastrulation?
Describe each step.

Back 14

Establishment of 3 germ layers from bilaminar embryonic disc

Heralds beginning of morphogenesis

1) Formation of primitive streak which establishes axial orientation of embryo (cranial/caudal, dorsal/ventral, right/left)

Front 15

Fate of epiblast.

Back 15

Gives rise to all three germ layers in embryo via gastrulation

Front 16

Ectoderm derivatives

Back 16

CNS, PNS
Epidermis
Sensory epithelia of eye, ear, nose
Mammary, pituitary, subcutaneous glands
Tooth enamel
NCCs

Front 17

Mesoderm derivatives

Back 17

CT
Cartilage, Bone, Muscle
Heart, blood, LVs
Kidneys, ovaries/testes, genital ducts, spleen
Seroud membranes lining body cavities
Adrenal Cortex

Front 18

Endoderm derivatives

Back 18

Epithelium of GI, resp tract
Parenchyma of thyroid, parathyroid, thmus, liver, pancreas
Epithelium of bladder and most of urethra

Front 19

Summarize the events of week 3 of gestation.

Back 19

Create trimlaminar embryonic disc during gastrulation

Form 3 germ layers

Form notochord, NT, NCC, coelom, primordial CV system

Front 20

When does organogenesis occur?

Back 20

Weeks 4-8 of embryology

Front 21

What is decidualization?

Function of decidua?

Back 21

Secretory transformation of uterine glands
Influx of uterine NK cells
Vascular remodeling

Decidual fn:
Nutrition
Regulation of trophoblast invasion
Protects against inflamm/oxidative insults
Dampen maternal immune response
Hormone production to preserve pregnancy

Front 22

What cells line the inner and outer layers of the horionic villi?

Back 22

Inner layer: cytotrophoblast

Outer: syncytiotrophoblast

Front 23

Function of chorionic villi?

Back 23

Exchange of material between mother and fetus

Front 24

Where is fetal blood located? Maternal blood? How do they interact?

Back 24

Fetal blood in capillaries of chorionic villi

Maternal blood in intervillous space (from lacunae)

Maternal blood enters intervillous space from spiral arteries in decidua, chorionic villi then directly bathe in maternal blood

Front 25

Role of cytotrophoblasts.
Subtypes and differences/functions.

Back 25

These are placental stem cells; undergo 2 differentiation pathways:
1) Villous: immotile, polarized, dx/dy into syncytiotrophoblasts and allow for maternal-fetal exchange of nutrients and waste; also metabolic, endocrine, and immune fns

2) Extravillous: (aka Intermediate cytotrophoblastic cells); motile, unpolarized, invasive and/or proliferative. Anchor fetus to mother.