Extraembryonic Membranes and Placentation Flashcards
1
Q
vertebrates are characterized by having and extra embryonic membrane called
A
the amnion
2
Q
what vertebrates have the amnion
A
reptiles, birds, mammals
3
Q
how many extraembryonic membranes develop?
A
4
4
Q
what is the first membrane to form
A
yolk sac
5
Q
yolk sac derived from
A
extraembryonic endoderm
6
Q
yolk sac is continuous with what
A
the primitive embryonic gut (midgut of GI tract);
7
Q
what is the connection between the yolk sac and gut
A
yolk stalk or vitelline duct
8
Q
the mesoderm that associates with the endoerm of yolk sac is the
A
splanchnic mesoderm
9
Q
complete wall of the yolk sac is composed of
A
endoderm and splanchnic mesoderm
10
Q
endoderm and splanchnic mesoderm is called
A
splanchnopleure
11
Q
flat disc
A
C shaped embryo with mid-ventral opening
12
Q
flat disc expands in what direction
A
cranially, caudally, and lateroventrally
13
Q
what extends through the opening in the flat disc
A
yolk sac
14
Q
what is the amnion
A
membrane that surrounds the embryo and separates it from immediate contact with environment
15
Q
the amnion is derived from and continuous with the
A
ectoderm
16
Q
amnion eventually forms what
A
outer layer of umbilical cord
17
Q
mesoderm associated with ectoderm of amnion is
A
somatic mesoderm
18
Q
complete wall of amniotic sac is composed of
A
ectoderm and somatic mesoderm
19
Q
ectoderm and somatic mesoderm are called
A
somatopleure
20
Q
what is the amniotic cavity
A
space between embryo and amnion
21
Q
what is the function of the amniotic fluid that fills the amniotic cavity
A
keeps embryo/fetus moist; protects from dessication
protect and cushion of embryo/fetus from physical forces
prevents adhesion of embryo/fetus to surroundings
22
Q
what are the sources of amniotic fluid
A
fetal urination
(continuously recycled: fetus urinates, swallos, abosred by fetal GI, and returned to maternal circulation via umblical vessels and placental exchange)
maternal plasma
23
Q
chorion membrane forms where
A
outside the amnion
24
Q
chorion is derived from
A
fetal ectoderm and trophoblasts
25
what mesoderm associates with ectoderm of chorion
somatic mesoderm
26
complete wall of chorion is composed of
ectoderm and somatic mesoderm
27
ectoderm and somatic mesoderm is
somatopleure
28
what is the mesoderm lined space between the amnion and chorion
extraembryonic coelom;
29
the body cavity associated with embryo body
intraembryonic coelom
30
what is the last membrane to develop
allantois
31
allantois is derived from
endoderm with splanchnic mesoderm
32
what is the complete wall of allantois called
splanchnopleure
33
diverticulum of hindgut enlarges into
space between amnion and chorion (extraembryonic coelom)
34
diverticulum of hindgut attached to
allantoic stalk
35
diverticulum of hindgut ____ system
extensive blood vessel system
36
what is also produced during allantois development
storage area for excretory substances produced during development
37
ovary of a bird ovulates ____ ova
yolk-rich
38
what makes up a majority of the avian reproductive tract
the oviduct
39
in the oviduct, there are secretions of ______ that surrounds the ova/zygote
albumen and fibrous membranes
40
what creates the hard shell of the egg
shell gland
41
where and when does fertilization occur in the avian
in the oviduct; before albumen and shell are added
42
can chickens lay unfertilized eggs?
yes
43
following gastrulation, extraembryonic germ layers (splanchnic mesoderm and endoderm or splanchnopleure) do what
expand over the yolk
44
avian yolk stalk formed connecting yolk sac with
embryonic/fetal gut
45
yolk is absorbed from sac
endothelial blood vessels, connect with blood vessels in splanchnic mesoderm and pass to embryo
46
yolk sac decreases in size as
embyro uses yolk (nutrition)
47
yolk eventually drawn into abdominal cavity and
incorporated into small intestine
48
when is the last of the yolk absorbed
shortly after hatching
49
avian amnion and chorion
"paired" folds; ectoderm, extraembyronic mesoderm, and trophoblasts (somatopleure) form
50
elevates
chorioamniotic folds
51
chorioamniotic folds expand ____
dorsally
52
chorioamniotic folds meet and fuse over _____ of embryo creating ______
dorsal midline; 2 layers of somatopleure (inner layer is amnion, outer layer is chorion)
53
avian allantoic splanchnic mesoderm fuses with
yolk sac splanchnic mesoderm
amnion somatic mesoderm
chorion somatic mesoderm of apposed to inner membrane of shel
54
vascularization of chorioallantoic membrane allows
o2/co2 exchange across shell
55
what happens to albumin during incubation
albumen loses water (increases in viscosity) and decreases in volume
56
expanding chorioallantoic membranes surrounds =
albumen sac
57
communication develops between albumen and amniotic cavity; how does embryo get nutrients?
embryo swallows
58
as embryo grows, _____ decrease in size
albuen sac
59
remaining albumen sac incorporated into
yolk sac (fuses with vitelline-allantoic membrane)
60
2 fibrous membranes are added around albumen
inner and outer
61
inner membrane eventually contacts with _____
chorion
62
outer membrane contacts
eggshell
63
what forms between the two membranes
air sac or air cell for gas exchange
64
what is an eggshell
a mineralized (calcium carbonate) or protein matrix
65
how does gas exchange occur
has pores to allow for gas exchange (allows air in and out of air sac)
66
when the egg is laid, the embryo is a ____
blastocyst
67
____ are just beginning to form
fetal membranes
68
the egg itself is mostly
yolk and ablumen with the embryo only a small disc sitting on the yolk
69
as the embryo grows, it will fill the eggshell, it and fetal membranes expand as albumen
decreases
70
yolk sac of mammalian extraembryonic membranes
develops even though there is no yolk
| may belarge in early embryo before placenta established
71
yolk sac placenta also known as
choriovitelline placenta
72
yolk sac placenta has extensive contact with
chorion
73
yolk sac becomes highly vascularized and absorbs
nutrients and oxygen
74
yolk sac placenta is definitive placenta of
most marsupials
75
yolk sac placenta is temporary placenta for
many mammals (excluding humans)- does not establish extensive, intimate contact with endometrium
76
amnion and chorion initial development is much like avian including
body folds (head fold, tail fold, lateral body fold) and chorioamniotic folds
77
chorion becomes
integral part of placneta
78
amnion expansion forms
umbilical cord encompassing umbilical vessels and allantoic stalk; grows as development proceeds
79
allantois fuses with
chorion to become part of the placenta (chorioallantoic) to establish extensive contact with endometrium
80
some marsupials develop ____ for the short intra-uterine development
primitive allantoic placenta
81
what is a placenta
an organ composed of maternal and fetal components
82
what are the functions of the placenta
O2/CO2, nutrient and waste exchange
acts as an endocrine organ (progensterone or chorionic gonadotropin in mares);
regulated barrier betwen fetal and maternal circulation
83
what is the placental labrynth
interdigitating folds, increased surface area for exchange
84
what determines the gross characteristics of the placenta
chorionic villi and relationship with endometrium
85
what animals have diffuse
horse and pig
86
what is diffuse
entire chorioallantois
87
what animals have cotyledonary
ruminants
88
what is cotyledonary
small areas of chorioallantois (cotyledons) attach to caruncles (maternal); together called placentome
89
what animals have zonary
carnivores
90
what is zonary
circumferential area of mid-chorioallantoic
91
discoid occurs in what animals
primates and rodents
92
what is discoid
disc-shaped area of chorioallantois
93
placenta is a ___ structure
layered
94
fetal layers include
```
fetal endothelium/fetal capillaries (deepest layer)
fetal CT
fetal epithelium (chorionic feal membrane ectoderm/trophoblasts)
```
95
maternal layers include
uterine epithelium
uterine CT
maternal vascular endothelium of capillaries
96
what animals have epitheliochorial placenta
horse, donkey, pigs
97
what is epitheliochorial
endometiral epithelium with chorionic epithelium; endometrial epithelium remains intact
98
syndesmochorial placenta is found in
ruminants
99
what is syndesmochorial layers
uterine connective tissue with chorionic epithelium; removal of uterine epithelium; single epithelial layer (contains epithelial cell of fetal and maternal origin)
*adhered only at cotyledons*
100
endotheliochorial occurs in
dogs and cats
101
endotheliochorial layers
endometrial capillaries with chorionic epithelium
| uterine epithelium and uterine connective tissue removed
102
hemochorial occurs in
rodents and primates
103
hemochorial laers
maternal blood and chorionic epithelium; uterine epithleium, uterine connective tissue, and endometiral capillary endothelium removed
104
canine/dog degree of implantation
conjoined/deciduate
105
feline degree of implantation
conjoined, deciduate
106
ruminants, equine, and porcine degree of implantation
apposed, nondeciduate
107
endometrial cups are unique in the
horse
108
what are endometrial cups
ulcer like structures (2mm to 5 cm) developed at chorionic girdle
109
how do these endometrail cups develop
fetal epithelial cell migrate into endometrial stroma and burry themselves; causing discrete, pale raised plaques in endometrium; triggers an immune response necessary for survival of pregnancy
110
endometrial cups are a source of
chorionic gonadotropin
111
endometrial cups develop at day
35 of gestation
112
endometrial cups regress at day
120 of gestation
113
once endometrial cups are formed, will termination of pregnancy alter course?
no; pregnancy serum will test positive until cups regress; and estruss will not resume until cups have regressed
