Extraembryonic Membranes and Formation of Placental Complex Flashcards

1
Q

what makes eem distinct

A

upon formation of 3 body folds (head, lateral, tail)

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2
Q

inner and outer layer of amnion

A

ecto (I) and eem (O)

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3
Q

inner and outer layer of chorion

A

eem (I) and ectoderm (O)

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4
Q

inner and outer layer of yolk sac

A

endoderm (I) and eem (O)

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5
Q

inner and outer layer of allantois

A

endoderm (I) and eem (O)

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6
Q

eem that are somatopleure in origin

A

amnion and chorion

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7
Q

eem that are splanchopleure in origin

A

yolk sac and allantois

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8
Q

development of chick embryo

A

oviparous

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9
Q

development of mammalian embryo

A

viviparous

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10
Q

how does placenta form

A

as chorionic villi > invade endometrium > breakdown maternal BVs > exchange and absorption of materials

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11
Q

what makes up the umbilical cord

A

connecting stalk, yolk stalk > housed by amnion

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12
Q

what separates ICM and trophoblast

A

amniotic cavity

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13
Q

yolk sac and function

A

1st to appear, grows over yolk mass
functions: makes yolk soluble materials, cell lining of endometrium bvs, hematopoiesis, PGCs

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14
Q

amnion and function

A

encloses amniotic cavity
protects embryo from adhesions and mechanical stress

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15
Q

chorion and function

A

chick: transport shell to embryo circulation > beak and skeleton & exchange of respi gases
mammals: respiration, filtration, HORMONE PRODUCTION

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16
Q

allantois and function

A

ventral wall of hindgutt
mesoderm fused with chorion (forming chorioallantoic membrane) and amnion
function: wastes and gas exchange
c - nitrogenous wastes
m - vascular network of placenta

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17
Q

function of chorioallantoic membrane

A

efficient respiratory structure

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18
Q

explain how yolk sac is formed

A

layer of mesodermal cells around edges of blastocyst > forms complete pouch (visible after 10d fertilization)

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19
Q

explain how amnion is formed

A

cells from blastodisc > migrates around a cavity separating ICM and trophoblast (amniotic cavity) and away from disc, moving between ectodermal lining of amniotic cavity

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20
Q

what forms the large part of the placenta

A

amnionic ectoderm, extraembryonic endoderm, yolk sac, extraembryonic mesoderm

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21
Q

explain formation of allantois

A

begins as outpocketing of the endoderm (hindgut) > tip grows toward the wall of blastocyst > surrounded by mesodermal cells

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22
Q

explain formation of chorion

A

mesoderm associated with allantois spread around blastocyst > mesoderm and trophoblast combination

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23
Q

what houses the blood vessels and allantois

A

chorionic and connecting stalk

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24
Q

this is the combination of the extraembryonic membrane and lining of the uterus;
the site of physiological exchange between mother and embryo

A

placenta

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25
Q

furnished by extraembryonic membranes

A

fetal tissue

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26
Q

furnished by uterine endometrium

A

maternal tissue

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27
Q

fetal tissue is largely contributed by what extraembryonic membrane?

A

chorion

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28
Q

what are the types of placenta based on the degree of contact of placental components?

A

deciduous: villi are embedded, shedding and bleeding occurs, intimate contact
non-deciduous: NO shedding and bleeding, villi NOT embedded, loose contact

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29
Q

type of placenta wherein the villi are spread our and greater part of chorion surface is associated with endometrium
- example

A

diffused placenta
ex: pig

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30
Q

type of placenta wherein the contact is restricted to the localized patches of villi
- example of animal

A

cotyledonary
ex:sheep, cow, deer

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31
Q

type of placenta wherein the contact involved girdlike band encircling the blastocyst; villi are arranged in transverse zones and penetrate uterine wall
- example

A

zonary placenta
- carnivores, cats, dogs

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32
Q

type of placenta wherein the contact is restricted to a disc or plate; villi form a disc that is intimately connected to the uterine wall
- example

A

discoidal placenta
- humans, rodents, rabbits

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33
Q

type of placenta with only 4 tissue layers

A

endotheliochorial

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34
Q

type of placenta with only 3 tissue layers

A

hemochorial

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35
Q

type of placenta with 6 tissue layers

A

epitheliochorial

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36
Q

type of placenta wherein the endometrial epithelium is removed at implantation; unusual type

A

syndesmochorial placenta

37
Q

type of placenta with no maternal layers retained

A

hemochorial

38
Q

type of placenta where the chorionic folds line the wrinkled surface of uterine epithelium

A

folded
ex: swine

39
Q

type of placenta where the chorion develops into villi

A

villous
ex: primates ruminants

40
Q

type of placenta where the feto-maternal space forms a network

A

labyrinthine
ex. rodents

41
Q

5 steps in the formation of placental complex

A
  1. implantation
  2. differentiation of trophoblast
  3. formation of chorionic villi
  4. decidual reaction
  5. mature placenta
42
Q

location of fertilization

A

ampulla of oviduct

43
Q

what day is the implantation

A

day 7-10

44
Q

location of implantation

A

lining of uterus

45
Q

in the 4-5th day after fertilization, where is the blastocyst located

A

vicinity of the uterus

46
Q

when the blastocyst is in the vicinity of the uterus, what is secreted?

A

hCG

47
Q

what is responsible for the establishment and formation of the placenta?

A

endometrial surface

48
Q

hormone that is secreted for PTs when the blastocyst is in the vicinity of uterus

A

hCG

49
Q

hormone that downregulate hCG synthesis and upregulate TUN secretion

A

TGF-B and LIF

50
Q

directs cytotrophoblast differentiation towards a hormonally-active syncytiotrophoblast phenotype

A

cAMP and hCG

51
Q

this is secreted on the anchoring sites that mediates the attachment of the placenta to the uterus

A

TUN

52
Q

gestational length of humans

A

280

53
Q

at the point of contact of blastocyst with endometrium, what will proliferate?

A

trophoblast

54
Q

trophoblast differentiates into?

A

inner cytotrophoblast and outer syncytiotrophoblast

55
Q

differentiate inner cytotrophoblast and outer syncytiotrophoblast

A

cyto has distinct cellular boundaries while syncytio do not (continuous layer)

56
Q

after further invasion of syncytriotrophoblast, what will form?

A

chorionic villi

57
Q

process when trophoblast cells invades endometrium

A

placentation

58
Q

villi with blood vessels

A

tertiary villi

59
Q

base of chorion that gives rise to villi forms?

A

chorionic plate

60
Q

what mostly makes up the chorionic plate?

A

extraembryonic mesoderm

61
Q

with the extension of chorion and chorionic villi, what will start to invade intraembryonic area of chorion fusing with allantios duct

A

villous capillaries

62
Q

site of exchange between fetus and mother

A

placenta

63
Q

this is where gases and nutrients exchange

A

intervillous space

64
Q

transformation of the stromal cells of the endometrium

A

decidual reaction

65
Q

tissues that are shed at birth, made up of extraembryonic tissues + superficial layers of endometrial CT and epithelium

A

deciduum

66
Q

the part lost at pregnancy or at menses, also the part around ectopic pregnancy

A

decidua

67
Q

this is the actual site of implantation that lies between chorionic vesicle and uterine wall

A

decidua basalis

68
Q

this forms a capsule around the chorionic vesicle

A

decidua capsularis

69
Q

this is opposite to the site of actual implantation that consists of decidualized endometrium on the sides of uterus

A

decidua parietalis

70
Q

what structure will be pushed against the wall and will fuse with decidua parietalis

A

decidua capsularis

71
Q

smooth area of chorion that lacks villi; middle ply of amniotic sac

A

laeve

72
Q

chorion attached to d. basalis; fetal portion of placenta

A

frondosum

73
Q

superficial part of endometrium of pregnancy

A

d. capsularis (reflexa)

74
Q

non implantation area of uterus; outer ply of amnion

A

d. parietalis (vera)
pro gravid endo

75
Q

endometrium of pregnancy beneath chorionic sa; supplies maternal blood to placenta

A

d. basalis (serotina)

76
Q

cell type that will develop into the fetus

A

ICM

77
Q

cell type that will develop into the placenta and external membranes

A

trophoblasts

78
Q

in the process of implantation, blastocyst is first slowed down by long molecules called what?

A

mucin

79
Q

in day 9 of implantation site, what surrounds the embryo at this stage?

A

inner mononuclear cytotrophoblast and outer multinucleated syncytiotrophoblast
- vacuoles form > fused into lacunae (LACUNAR STAGE)

80
Q

at what stage is the basic structure of placent formed? this is where spiral arteries and uterine veins, as well as chorionic villi are present

A

4 weeks

81
Q

umbilical cord is enclosed by mesenchymal cells called

A

Whartons jelly

82
Q

what induces oxytocin receptors on uterus (secreted from ovary)

A

estrogen

83
Q

function of oxytocin?

A

stimulates uterus to contract
stimulates placenta to make prostaglandins

84
Q

function of prostaglandins

A

stimulate more contractions of uterus

85
Q

differentiate the 2 type of twins in terms of placenta and membranes

A
  • identical - 1 placenta (shared), and 1 outermembrane that envelopes both
  • fraternal - 2 different placenta and 2 separate amniotic sacs with own outermembrane each
86
Q

hormones that maintains endometrial lining > maintains pregnancy

A

progesterone

87
Q

hormone that maintains progesterone production until end of 1st trimester

A

human chorionic gonadotropin

88
Q

hormone that influences growth, lactation, lipid and carbohydrate metabolism

A

human placental lactogen (hPL)

89
Q

3 main functions of placenta

A
  1. physiological site of maternal-fetal exchange
  2. works as endocrine gland; hormone synthesis
  3. immunological barrier