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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
How many embryos must be present in pigs to prevent luteolysis?
At least four embryos.
21
What strategy do pigs use to prevent luteolysis?
They secrete estradiol from their trophectoderm, which causes PGF2α to be rerouted into the uterine lumen for degradation.
21
In which two species is a functional choriovitelline placenta seen?
Carnivores and horses
22
Which two types of placentas are classified based on their fusion with extraembryonic structures?
Choriovitelline placenta and chorioallantoic placenta
23
Which placenta type is the primary functional placenta in all domestic species?
The chorioallantoic placenta
24
Which two types of placentas are based on the distribution of the chorion frondosum?
Diffuse placenta and cotyledonary placenta
24
What is the structure formed when chorionic villi combine with caruncles in the endometrium in ruminants?
Placentomes
24
What is the type of placenta seen in carnivores, where the chorion frondosum is organized into a broad belt?
Zonary and lamellar placenta
25
Which species have an epitheliochorial placenta?
Pigs, horses, and ruminants.
25
Which type of placenta retains all six layers of maternal and fetal tissues?
Epitheliochorial placenta
26
What type of placenta is seen in ruminants, where some trophoblast cells fuse with maternal epithelial cells?
Synepitheliochorial placenta.
27
How many layers are retained in the endotheliochorial placenta seen in carnivores?
Four layers.
28
Which type of placenta is the most invasive, involving the loss of all maternal tissue layers?
Hemochorial placenta.
28
In which species is the hemochorial placenta found?
Rodents and humans.
29
Which type of placentation involves the sloughing off of the uterine endometrium during parturition?
Deciduate placentation.
30
Which species exhibit deciduate placentation?
Carnivores, primates, and rodents.
31
Which type of placentation occurs when the uterine endometrium remains intact during parturition?
Adeciduate placentation.
32
Which species have adeciduate placentation?
Ruminants (partial), horses, and pigs.
33
What is the function of the trophoblast in early embryo development?
Form the outer layer of the blastocyst and later contribute to placental formation.
34
What does the extra-embryonic coelom surround during placental development?
It surrounds the expanding allantois and the embryo.
35
What is the significance of the fusion between the definitive yolk sac and the chorion in some species?
It helps establish the choriovitelline placenta, which is functional in species like carnivores and horses.
36
Which hormone is essential for the maintenance of early pregnancy by preventing luteolysis?
Progesterone, primarily produced by the corpus luteum.
37
How does the presence of interferon-tau (IFN-t) in ruminants help maintain pregnancy?
inhibits the formation of oxytocin receptors, preventing luteolysis and sustaining progesterone levels.
38
Why is PGF2α important in the context of maternal recognition of pregnancy?
It triggers luteolysis, which would lead to the regression of the corpus luteum and termination of pregnancy if not prevented.
39
Which species exhibit non-invasive placentation, where the embryo does not invade the maternal endometrium?
Most domestic animals, except for carnivores.
40
What are the main components of the placental barrier in the chorioallantoic placenta?
The endothelium, chorioallantoic mesenchyme, and chorionic epithelium
41
What is the difference between chorion frondosum and chorion laeve?
Chorion frondosum is where placental exchange occurs, while chorion laeve is the smooth part not involved in placental formation.
42
What specific signal does the embryo use in pigs to alter the secretion of PGF2α during maternal recognition?
The production of estradiol by the trophectoderm around Days 11-12 of development.
43
44
In the endotheliochorial placenta, which two maternal tissue layers are lost?
The endometrial epithelium and connective tissue are lost, leaving only the maternal endothelium in contact with the trophoblast.
45
allantois develops as an ___ from the ____
evagination - hindgut
46
As the embryo grows, the allantois gradually expands into -?
extra-embryonic coelom
47
High levels of ____ are secreted into the ____ during proestrus and estrus.
estrogen - bloodstream
48
_____ predominates during the following periods of metestrus and diestrus when the early embryo moves from the _____ into the____.
Progesterone - oviduct into the uterus
49
in what animal the corpus luteum produces oxytocin as well as progesterone?
Ruminants
50
If the ___ attaches to the uterus, its ____ will produce interferon-tau (IFN-t), which will inhibit the formation of ____ ____ receptors.
blastocyst - trophectoderm - endometrial oxytocin
51
T OR F? Then in the presence of an embryo, oxytocin cannot stimulate the synthesis of PGF2α and luteolysis is prevented.
True
52
Pigs employ another strategy to interrupt the luteolytic pathway. Estradiol is produced from their ______ around the days __ to __ of development.
trophectoderm - day 11 to 12
53
On swine, it causes PGF2α to be secreted into the ____ instead of into the maternal blood stream.
uterine lumen into
54
A type of placenta where the yolk sac wall combines locally with the chorion to form an area for exchange.
Choriovitelline placenta
55
The region where the chorioallantois interacts with the endometrium to form placental structures.
Chorion frondosum
55
The primary functional placenta in all domestic species, formed by fusion between the allantoic wall and chorion.
Chorioallantoic placenta
55
A smooth surface area on the chorioallantois that does not engage in placental formation.
Chorion laeve
55
A structure formed in ruminants by the combination of cotyledons and caruncles in the endometrium.
Placentome
56
A type of placenta where the chorion frondosum is diffusely distributed over the entire chorioallantoic surface, seen in pigs and horses.
Diffuse placenta
56
A type of placenta in ruminants where chorion frondosum is organized into macroscopically visible tufts called cotyledons.
Cotyledonary placenta
57
A type of placenta in carnivores where chorion frondosum forms a broad belt around the embryo’s longitudinal axis.
Zonary placenta
58
The classification based on the number of tissue layers separating fetal and maternal circulations.
Placental barrier
59
A placentation type found in pigs, horses, and ruminants where no maternal tissue layers are lost, retaining all six layers.
Epitheliochorial placenta
60
A modified epitheliochorial placenta in ruminants where some trophoblast cells fuse with endometrial epithelial cells, retaining five layers.
Synepitheliochorial (or Syndesmochorial) placenta
61
A placental type found in carnivores where endometrial epithelium and connective tissue are lost, retaining four layers.
Endotheliochorial placenta
62
The most invasive placental type where all maternal tissue layers are lost, allowing direct contact with maternal blood. Seen in rodents and humans.
Hemochorial placenta
63
A classification based on whether the uterine endometrium is sloughed off during parturition.
Deciduate placenta
64
A type of placentation where the uterine endometrium remains intact during parturition, partially seen in ruminants, horses, and pigs.
Adeciduate placenta
65
The classification describing a placenta with no maternal tissue layer intact, as seen in rodents and primates.
Hemochorial
66
A specific type of placenta in carnivores where connective tissue and endometrial epithelium are lost, but endothelial layers remain.
Endotheliochorial
67
The classification term referring to a placenta with layers intact in maternal and fetal tissues, characteristic of species such as pigs, horses, and ruminants.
Epitheliochorial
68
The layer of cells derived from the chorion in the fetal part of the placenta that interacts with maternal tissue.
Trophoblast
69
The vascularized maternal tissue that combines with the fetal cotyledons to form placentomes in ruminants.
Caruncles
70
A specific placental structure formed by the fusion of chorionic villi into larger tufts in ruminants.
Cotyledons
71
Specialized trophoblast cells in ruminants that fuse with endometrial epithelial cells to modify the epitheliochorial placenta.
Binucleate cells
72
The term used for connective tissue found within the fetal part of the chorioallantoic placenta, originating from fused somatic and visceral mesoderm.
Chorioallantoic mesenchyme
73
: The cell type lining the fetal blood vessels in the chorioallantoic placenta.
Endothelium
74
The outermost layer of the fetal side of the placenta, consisting of trophoblast cells.
Chorionic epithelium

Embryology (4 decks)

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