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Embryology > Lesson 9 > Flashcards

Lesson 9 Flashcards

1
Q

Upon entering the uterine cavity, the embryo
is initially nourished by secretions from?

A

uterine glands or endometrial glands

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2
Q

These secretion products are called?

A

histotrophe or uterine milk

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3
Q

Histotrophe is not enough to nourish the embryo so to counteract it, the embryonic tissues
establishes close connections with the?

A

maternal circulatory system

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4
Q

the embryo to import bloodborne
maternal nutrients called?

A

hemotrophe

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5
Q

histotrophe and hemotrophe are
referred to as?

A

embryotrophe

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6
Q

To accomplish exchange between the mother
and her embryo a temporary organ is formed and is known as?

A

placenta

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7
Q

In what species, where the newly hatched
blastocyst attaches to the endometrial
epithelium and, the embryo actually
penetrates the epithelium and invades the endometrial connective tissue which it becomes completely embedded.

A

rodents and primates

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8
Q

the embryo leaves the
uterine lumen, and this process is called?

A

implantation

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9
Q

In domestic animals invasion of the
endometrium does not occur. True or False?

A

True

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10
Q

The embryo remains attached to the internal
endometrial surface throughout what period?

A

Gestation

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11
Q

What happens to the embryo after blastulation in most domestic species?

A

It reaches the uterine cavity before blastulation begins

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12
Q

What two structures does the inner cell mass differentiate into after hatching from the zona pellucida?

A

The epiblast and hypoblast

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12
Q

What are the two main components of the embryo at the end of blastulation?

A

The trophectoderm and the inner cell mass

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12
Q

What is the enclosed cavity that forms during early development called?

A

The primitive yolk sac

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13
Q

What happens to the extra-embryonic mesoderm during gastrulation?

A

It splits into somatic and visceral sheets.

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14
Q

What forms from the body foldings of the embryo during gastrulation?

A

The primitive gut and the definitive yolk sac.

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15
Q

Which structure fuses with the chorion to establish the choriovitelline placenta in some species?

A

The definitive yolk sac.

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16
Q

What structure develops as an evagination from the hindgut?

A

The allantois.

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17
Q

Which two structures fuse to form the chorioallantois, which gives rise to the chorioallantoic placenta?

A

The allantoic wall and the chorion

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18
Q

What two hormones are primarily involved in preparing the uterus for placentation?

A

Estrogens and progesterone

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19
Q

Which hormone produced by the corpus luteum stimulates the endometrium to synthesize prostaglandins (PGF2α), causing luteolysis?

A

Oxytocin

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19
Q

Which hormone predominates during metestrus and diestrus, preparing the uterus for embryo implantation?

A

Progesterone

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19
Q

What process is required to prevent luteolysis and maintain pregnancy?

A

Maternal recognition of pregnancy

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20
Q

What substance does the embryo in ruminants produce to block the formation of oxytocin receptors?

A

Interferon-tau (IFN-t).

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21
Q

How many embryos must be present in pigs to prevent luteolysis?

A

At least four embryos.

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21
Q

What strategy do pigs use to prevent luteolysis?

A

They secrete estradiol from their trophectoderm, which causes PGF2α to be rerouted into the uterine lumen for degradation.

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21
Q

In which two species is a functional choriovitelline placenta seen?

A

Carnivores and horses

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22
Q

Which two types of placentas are classified based on their fusion with extraembryonic structures?

A

Choriovitelline placenta and chorioallantoic placenta

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23
Q

Which placenta type is the primary functional placenta in all domestic species?

A

The chorioallantoic placenta

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24
Q

Which two types of placentas are based on the distribution of the chorion frondosum?

A

Diffuse placenta and cotyledonary placenta

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24
Q

What is the structure formed when chorionic villi combine with caruncles in the endometrium in ruminants?

A

Placentomes

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24
Q

What is the type of placenta seen in carnivores, where the chorion frondosum is organized into a broad belt?

A

Zonary and lamellar placenta

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25
Q

Which species have an epitheliochorial placenta?

A

Pigs, horses, and ruminants.

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25
Q

Which type of placenta retains all six layers of maternal and fetal tissues?

A

Epitheliochorial placenta

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26
Q

What type of placenta is seen in ruminants, where some trophoblast cells fuse with maternal epithelial cells?

A

Synepitheliochorial placenta.

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27
Q

How many layers are retained in the endotheliochorial placenta seen in carnivores?

A

Four layers.

28
Q

Which type of placenta is the most invasive, involving the loss of all maternal tissue layers?

A

Hemochorial placenta.

28
Q

In which species is the hemochorial placenta found?

A

Rodents and humans.

29
Q

Which type of placentation involves the sloughing off of the uterine endometrium during parturition?

A

Deciduate placentation.

30
Q

Which species exhibit deciduate placentation?

A

Carnivores, primates, and rodents.

31
Q

Which type of placentation occurs when the uterine endometrium remains intact during parturition?

A

Adeciduate placentation.

32
Q

Which species have adeciduate placentation?

A

Ruminants (partial), horses, and pigs.

33
Q

What is the function of the trophoblast in early embryo development?

A

Form the outer layer of the blastocyst and later contribute to placental formation.

34
Q

What does the extra-embryonic coelom surround during placental development?

A

It surrounds the expanding allantois and the embryo.

35
Q

What is the significance of the fusion between the definitive yolk sac and the chorion in some species?

A

It helps establish the choriovitelline placenta, which is functional in species like carnivores and horses.

36
Q

Which hormone is essential for the maintenance of early pregnancy by preventing luteolysis?

A

Progesterone, primarily produced by the corpus luteum.

37
Q

How does the presence of interferon-tau (IFN-t) in ruminants help maintain pregnancy?

A

inhibits the formation of oxytocin receptors, preventing luteolysis and sustaining progesterone levels.

38
Q

Why is PGF2α important in the context of maternal recognition of pregnancy?

A

It triggers luteolysis, which would lead to the regression of the corpus luteum and termination of pregnancy if not prevented.

39
Q

Which species exhibit non-invasive placentation, where the embryo does not invade the maternal endometrium?

A

Most domestic animals, except for carnivores.

40
Q

What are the main components of the placental barrier in the chorioallantoic placenta?

A

The endothelium, chorioallantoic mesenchyme, and chorionic epithelium

41
Q

What is the difference between chorion frondosum and chorion laeve?

A

Chorion frondosum is where placental exchange occurs, while chorion laeve is the smooth part not involved in placental formation.

42
Q

What specific signal does the embryo use in pigs to alter the secretion of PGF2α during maternal recognition?

A

The production of estradiol by the trophectoderm around Days 11-12 of development.

43
Q
A
44
Q

In the endotheliochorial placenta, which two maternal tissue layers are lost?

A

The endometrial epithelium and connective tissue are lost, leaving only the maternal endothelium in contact with the trophoblast.

45
Q

allantois develops as an ___ from the ____

A

evagination - hindgut

46
Q

As the embryo grows, the allantois gradually
expands into -?

A

extra-embryonic coelom

47
Q

High levels of ____ are secreted into the
____ during proestrus and estrus.

A

estrogen - bloodstream

48
Q

_____ predominates during the
following periods of metestrus and diestrus
when the early embryo moves from the
_____ into the____.

A

Progesterone - oviduct into the uterus

49
Q

in what animal the corpus luteum produces
oxytocin as well as progesterone?

A

Ruminants

50
Q

If the ___ attaches to the uterus, its ____ will produce interferon-tau (IFN-t), which will inhibit the formation of ____ ____ receptors.

A

blastocyst - trophectoderm - endometrial oxytocin

51
Q

T OR F?
Then in the presence of an embryo, oxytocin
cannot stimulate the synthesis of PGF2α and luteolysis is prevented.

A

True

52
Q

Pigs employ another strategy to interrupt the luteolytic pathway.

Estradiol is produced from their ______ around the days __ to __ of development.

A

trophectoderm - day 11 to 12

53
Q

On swine, it causes PGF2α to be secreted into the ____ instead of into the maternal
blood stream.

A

uterine lumen into

54
Q

A type of placenta where the yolk sac wall combines locally with the chorion to form an area for exchange.

A

Choriovitelline placenta

55
Q

The region where the chorioallantois interacts with the endometrium to form placental structures.

A

Chorion frondosum

55
Q

The primary functional placenta in all domestic species, formed by fusion between the allantoic wall and chorion.

A

Chorioallantoic placenta

55
Q

A smooth surface area on the chorioallantois that does not engage in placental formation.

A

Chorion laeve

55
Q

A structure formed in ruminants by the combination of cotyledons and caruncles in the endometrium.

A

Placentome

56
Q

A type of placenta where the chorion frondosum is diffusely distributed over the entire chorioallantoic surface, seen in pigs and horses.

A

Diffuse placenta

56
Q

A type of placenta in ruminants where chorion frondosum is organized into macroscopically visible tufts called cotyledons.

A

Cotyledonary placenta

57
Q

A type of placenta in carnivores where chorion frondosum forms a broad belt around the embryo’s longitudinal axis.

A

Zonary placenta

58
Q

The classification based on the number of tissue layers separating fetal and maternal circulations.

A

Placental barrier

59
Q

A placentation type found in pigs, horses, and ruminants where no maternal tissue layers are lost, retaining all six layers.

A

Epitheliochorial placenta

60
Q

A modified epitheliochorial placenta in ruminants where some trophoblast cells fuse with endometrial epithelial cells, retaining five layers.

A

Synepitheliochorial (or Syndesmochorial) placenta

61
Q

A placental type found in carnivores where endometrial epithelium and connective tissue are lost, retaining four layers.

A

Endotheliochorial placenta

62
Q

The most invasive placental type where all maternal tissue layers are lost, allowing direct contact with maternal blood. Seen in rodents and humans.

A

Hemochorial placenta

63
Q

A classification based on whether the uterine endometrium is sloughed off during parturition.

A

Deciduate placenta

64
Q

A type of placentation where the uterine endometrium remains intact during parturition, partially seen in ruminants, horses, and pigs.

A

Adeciduate placenta

65
Q

The classification describing a placenta with no maternal tissue layer intact, as seen in rodents and primates.

A

Hemochorial

66
Q

A specific type of placenta in carnivores where connective tissue and endometrial epithelium are lost, but endothelial layers remain.

A

Endotheliochorial

67
Q

The classification term referring to a placenta with layers intact in maternal and fetal tissues, characteristic of species such as pigs, horses, and ruminants.

A

Epitheliochorial

68
Q

The layer of cells derived from the chorion in the fetal part of the placenta that interacts with maternal tissue.

A

Trophoblast

69
Q

The vascularized maternal tissue that combines with the fetal cotyledons to form placentomes in ruminants.

A

Caruncles

70
Q

A specific placental structure formed by the fusion of chorionic villi into larger tufts in ruminants.

A

Cotyledons

71
Q

Specialized trophoblast cells in ruminants that fuse with endometrial epithelial cells to modify the epitheliochorial placenta.

A

Binucleate cells

72
Q

The term used for connective tissue found within the fetal part of the chorioallantoic placenta, originating from fused somatic and visceral mesoderm.

A

Chorioallantoic mesenchyme

73
Q

: The cell type lining the fetal blood vessels in the chorioallantoic placenta.

A

Endothelium

74
Q

The outermost layer of the fetal side of the placenta, consisting of trophoblast cells.

A

Chorionic epithelium

Embryology (4 decks)

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