Implantation and Placental Development

Question 1

embryo?

Answer 1

organism in early stages of development which has not yet acquired anatomical form making it recognizable as a specific species

Question 2

fetus?

Answer 2

potential offspring that is generally recognizable as a member of a given species

Question 3

conceptus?

Answer 3

the products of conception: 1) the embryo during early stages 2) the embryo and extraembryonic membranes during preimplantation stage and 3) the fetus and placenta during postattachment stages

Question 4

___ make up the fetal side of the placenta in farm animals.

Answer 4

fetal extraembryonic membranes

Question 5

What are the 5 fetal extraembryonic membranes?

Answer 5

chorion; allantois; umbilical cord; amnion; yolk sac

Question 6

chorion?

Answer 6

encloses embryo and all other extraembryonic membranes.

Question 7

What is the site of attachment to the uterus composed of?

Answer 7

mesoderm and trophectoderm (produce hormones)

Question 8

allantois?

Answer 8

contains blood vessels that connect fetal circulation with placental circulation.

Question 9

An outgrowth of the hind gut that fuses with the chorion forms ____ which is composed of the mesoderm and endoderm.

Answer 9

chorioallantois placenta

Question 10

In humans ___ regresses after formation leaving allantois blood vessels in the umbilical cord which infiltrates the chroion.

Answer 10

allantois

Question 11

umbilical cord?

Answer 11

encloses allantoic blood vessels and forms the vascular link between the mother and fetus

Question 12

amnion?

Answer 12

fluid-filled sac that encloses the fetus and provides stability and protection, supplies water and other materials from amniotic fluid

Question 13

In humans __ will fuse with the chorion.

Answer 13

amnion

Question 14

amniocentesis?

Answer 14

in humans, a procedure to check for sex of fetus: small needle inserted into amnion and fluid extracted (genetic disorders indicated as well) - diagnostic test for abnormalities in fetal cells as well as sex

Question 15

yolk sac?

Answer 15

develops early, lines trophoblast and blastocoele cavity. Early, it provides red blood cells and primordial germ cells and serum-like proteins as it serves a function similar to the liver.

Question 16

__ regresses with fetal development.

Answer 16

yolk sac

Question 17

From inside out, what are the layers for the differentiation of conceptus cell types?

Answer 17

primative gut, endoderm, mesoderm, trophectoderm, inner cell mass, ectoderm

Question 18

In order from inside out, what are the layers of the extraembyronic membranes?

Answer 18

yolk sac, endoderm, mesoderm, ectoderm, chorion; formation of embryo, allantoic cavity, allantois, amnion, chorion

Question 19

What are the four placental membranes?

Answer 19

chorion, yolk sac, amnion, allantois

Question 20

The blood vessels that form are connected to the fetus through the ___.

Answer 20

umbilical cord

Question 21

___ expands to fill the chorion.

Answer 21

allantoic cavity

Question 22

What occurs prior to implantation?

Answer 22

blastocyst is bathed in uterine secretions and draws upon them for growth and survival; accumulation of organic molecules and ions by active cellular transport; exchanges of CO2 and O2 by simple diffusion

Question 23

T/F: This is a limit to the size a free living conceptus can obtain before the CO2 and O2 exchange mechanism can become inadequate.

Answer 23

T

Question 24

placenta?

Answer 24

zone of highly vascular contact between mother and conceptus, where two discrete ciruculations lie in close contact for rapid and efficient transfer of materials

Question 25

What are the two types of implantation?

Answer 25

invasive; noninvasive

Question 26

invasive implantation?

Answer 26

conceptus breaks through surface endometrial eptithelium and invades underlying stroma

Question 27

noninvasive implantation?

Answer 27

endometrial epithelium is retained (or at least breached only sporadically, transiently, or much later)

Question 28

What is the mechanism of the trophoblast and luminal epithelium attachment?

Answer 28

through physical contact by interlocking microvilli

Question 29

___ attachment induces vascularization and differentiation of underlying stroma.

Answer 29

invasive

Question 30

Decidualization of the uterus occurs during __ implantation.

Answer 30

invasive

Question 31

What is decidualization?

Answer 31

1) edema - bumps full of blood form on uterus 2) changes in stromal cell morphology 3) sprouting and growth of capillaries in endometrium 4) decidua

Question 32

decidua?

Answer 32

endometrial component of placenta; the place where implantation takes place in species that undergo decidualization

Question 33

Trophoblast cells migrate and invade stroma in __ implantation.

Answer 33

invasive

Question 34

cytotrophoblast?

Answer 34

unicellular trophoblast cells (one cell, one nucleus)

Question 35

synctiotrophoblast?

Answer 35

fused cells which form a structure call the syncytium (fusing together makes gonadotropins)

Question 36

The uterine gland and stromal tissue adjacent to invading trophoblasts are destroyed, taken up and utilized by the conceptus (passed to developing blood vascular system and distributed to growing embryo) in __ implantation.

Answer 36

invasive

Question 37

interstitial invasion?

Answer 37

stroma is invaded so deeply that uterine epithelium grows back over conceptus (human, chimp)

Question 38

eccentric invasion?

Answer 38

secondary contact with uterine epithelium on side opposite where implantation initiated - may result in two sites of placental development (bidiscoid placenta of rhesus, zonary placenta (dog, cat)

Question 39

What three factors contribute to noninvasive implantation?

Answer 39

1) attachment initiated relatively late 2) prolonged free living period 3) great outgrowth of trophoblast

Question 40

placentation?

Answer 40

a term often used to describe noninvasive implantation

Question 41

chroionic villi?

Answer 41

projections on chorion that contact (interdigitate) with uterine tissue to bring fetal blood vessels in close proximity to maternal blood vessels

Question 42

What are the 5 ways that the placenta is classified by shape?

Answer 42

1) cotyledonary 2) diffuse 3) zonary 4) incomplete zonary 5) discoid

Question 43

cotyledonary classification?

Answer 43

noninvasive, chorionic villi restricted to specialized areas called cotyledons

Question 44

cotyledon?

Answer 44

specialized areas on fetal placental membrane

Question 45

caruncle?

Answer 45

maternal specialized regions on uterus to which the cotyledons attach

Question 46

placentome?

Answer 46

cotyledon and caruncle together

Question 47

Diffuse placental classification?

Answer 47

noninvasive, chrorionic villi distributed over entire surface of chorionic sac

Question 48

Zonary placental classification?

Answer 48

invasive, chorionic villi restricted to an equitorial girdle around the placenta

Question 49

Incomplete placental classification?

Answer 49

invasive, chorionic villi do not circumscribe placenta

Question 50

Discoid placental classification?

Answer 50

invasive, chorionic villi arranged in a circular plate

Question 51

Cow, sheep, deer have what type of placental classification?

Answer 51

cotyledonary

Question 52

pig, horse, camel whale, dolphin have what placental classification?

Answer 52

diffuse

Question 53

dog, cat, seal have what placental classification?

Answer 53

zonary

Question 54

mink, bear, raccoon have what placental classification?

Answer 54

incomplete zonary

Question 55

Primates, mouse, rat, rabbit, bat have what placental classification?

Answer 55

discoid

Question 56

interstitial discoid?

Answer 56

invasion so deep that epithelium of endometrium grows back over invading placenta (in humans, chimps)

Question 57

eccentric discoid?

Answer 57

bidiscoid, rhesus. secondary contact with uterine endometrium on side opposite of original implantation results in placental development on two sides of uterus

Question 58

delayed implantation?

Answer 58

embryos of most species implant shortly after entering uterus but in a number of species implantation is delayed.

Question 59

obligatory delayed implantation?

Answer 59

implantation delayed several months, may breed in fall and implant in spring; bats, bears, seals, armadillo, badger, weasel

Question 60

embryonic diapause?

Answer 60

little embryonic growth

Question 61

facultative delayed implantation?

Answer 61

induced by lactation and suckling; inhibits FSH and E2 secretions; may be induced by single injection E2 on a P4 background; E acts through ER and uterine metabolite catechol estrogens to activate embryo to implant

Question 62

The blood gas exchange at the chorion is a __ attachment.

Answer 62

endometrium

Question 63

The placenta is highly permeable to water and electrolytes stored in exchange between which two fluids?

Answer 63

allantoic and amniotic

Question 64

The placenta coverts glucose to fructose which allows for storage in __ fluid.

Answer 64

allantoic

Question 65

How is fetal fat formed?

Answer 65

from FA transferred across the placenta

Question 66

How does the fetus make proteins?

Answer 66

from transferred amino acids

Question 67

T/F: Fat soluble vitamins cross the placenta easier than the water soluble vitamins.

Answer 67

F

Question 68

T/F: In domestic species, minerals are transferred across the placenta.

Answer 68

T

Question 69

Antibodies to fight disease do/do not cross the placenta. Why or why not?

Answer 69

do not: the newborn will get these antibodies from the first milk (colostrum)