Lectures 13, 14 and 15: Embryology Flashcards
(139 cards)
1
Q
gastrulation definition/transformation
A
-formation of 3 germ layers
-go from bilaminar disk containing epiblast and hypoblast into trilaminar disc of 3 germ layers
2
Q
corona radiata composed of
A
-zona pellucida
-layers of follicular cells
3
Q
what is the zona pellucida
A
glycoprotein coat
4
Q
acrosome cap definition and function
A
-specialized lysosome
-prevents sperm from getting to egg
5
Q
capacitation process
A
-period between ejaculation and when the sperm is traveling to the egg
-get degradation of the acrosome cap so that sperm can fertilize egg
6
Q
location and timing of ejaculation and capacitation is _________ specific
A
species
7
Q
where does ejaculation and capacitation occur in dogs
A
uterus
8
Q
where does ejaculation and capacitation occur in cats
A
vagina
9
Q
purpose of cilia in oviduct
A
help fertilized egg
10
Q
what makes oocyte impenetrable to other sperm
A
zona reaction
11
Q
what causes the zona reaction
A
sperm in oocyte without its plasma membrane
12
Q
how does sperm penetrate oocyte (process)
A
-as acrosome wall perforates, sperm moves through follicular cells
-sperm moves through corona radiata zona pellucida
-zona reaction
13
Q
oocyte definition
A
-female gamete cell produced by ovaries
14
Q
fertilized oocyte becomes
A
zygote
15
Q
what is the female pronucleus
A
-oocyte after completing second meiotic division but before fertilization
16
Q
male pronucleus
A
forms from enlarged sperm nucleus
17
Q
what structure is absent/disappears in female pronucleus
A
corona radiata
18
Q
how is diploid zygote formed from male and female pronucleus
A
-pronucleus membranes breakdown and fuse
19
Q
blastomere definition
A
new embryonic cell produced by mitosis/cleavage
20
Q
blastomeres get (bigger or smaller) with each cell division?
A
smaller
21
Q
morula definition
A
superficial layer surrounding central core of compacted cells (i.e. blastomeres)
22
Q
what structure surrounds the cluster of blastomeres following mitosis
A
morula
23
Q
when are blastomeres no longer totipotent
A
when compaction occurs –> inner and outer cell masses created
24
Q
what are the 2 layers of cell masses called in compacted blastomere
A
trophoblast = external layer
embryoblast = inner layer
25
what does trophoblast ultimately become
placenta
26
what does embryoblast become
fetus/conceptus
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what is the first cavity created
blastocystic cavity
28
how is the blastocystic cavity created
secretions from blastomeres
29
structural function/location of zona pellucida
surround trophoblasts
30
2 poles of ovum/blastocyst
-animal pole
-vegetal pole
31
animal pole is located near what cell mass
embryoblast (inner cell mass)
32
vegetal pole is located where
away from embryoblast, closer to blastocystic cavity
33
function of trophoblast
protect embryoblast
34
what is rauber's layer
layer of cells directly above embryoblast
35
what happens to rauber's layer
disintegrates
36
early vs late embryoblast
late = hatching occurs out of zona pellucida
37
where does blastocyst emerge from (what is hatching?)
zona pellucida
38
when and why does hypoblast emerge
-as rauber's layer disintegrates
-enclose blastocystic cavity
39
when does blastocystic cavity become exocoelemic cavity
when hypoblast emigrates to enclose blastocystic cavity (forms at ventral surface of embryoblast)
-see staggered clumps of hypoblast starting to surround cavity
40
at what stage is cavity named blastocystic cavity
at stage with trophoblast and embryoblast
41
how does name of blastocystic cavity change
blastocystic --> exocoelemic --> primitive yolk sac --> definitive yolk sac
42
when does exocoelemic cavity become primitive yolk sac
when hypoblast extends to surround exocoelemic cavity (see full enclosed layer of hypoblast around cavity)
43
what replaces rauber's layer
tight junctions of epiblast
44
what 2 structures form the bilaminar embryonic disc
epiblast and adjacent hypoblast
45
location of ejaculation in cattle
vagina
46
location of ejaculation in horses
uterus
47
where does fertilization occur
oviduct
48
effect of zona reaction
hardens corona radiata so other sperm can't enter
49
where is implantation in all domestic animals occur (relatively)
-centric/superficial
-conceptus fills up uterine lumen
50
pronucleus stage for female (4 things)
-2nd meiotic division complete
-corona radiata disappears
-zona pellucida remains and hardens
-have 2 polar bodies
51
pronucleus stage males (2)
-from enlarged sperm nucleus
-head and tail degenerate
52
steps from mature oocyte to blastocyst formation
-oocyte -->pronucleus --> zygote --> cleavage/mitosis --> marula formation --> blastocyst formation
53
when does extraembryonic mesoderm start forming
after conceptus implantation into uterine lumen
54
where will extraembryonic mesoderm be formed
between trophoblast and hypoblast layers
55
what will form the chorion
trophoblast
56
what cells form the amniotic membrane
epiblast
57
what forms after extraembryonic mesoderm
prechordal plate
58
how prechordal plate is formed
-some hypoblast cells become columnar and form thickened circular area = prechordal plate
59
what will prechordal plate become
mouth
60
what structure does gastrulation begin with
primitive streak
61
structures inside primitive streak (3)
-primitive groove in primitive streak
-primitive node at top of primitive streak
-primitive pit at top of primitive groove
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where do all 3 germ layers originate from
epiblast
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if nothing changes to cells (i.e. don't migrate), what germ layer is formed
ectoderm
64
if cells do not become ectoderm, where do they go
migrate through primitive groove in primitive streak
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mesenchymal cells =
migrating cells
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endoderm will replace what cells
hypoblast
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ectoderm becomes (main)
-epidermis
68
what does mesoderm form (important structure)
notochord
69
what happens first: gastrulation or notochord formation
gastrulation
70
function of notochord (4)
-defines axis of embryo
-provides rigidity
-future site of vertebral bodies (axial skeleton)
-primary inducer of future structures
71
how is notochord formed
-prenotochordal cells invaginate into primitive pit and move cranially toward the midline until they reach the prechordal plate to form notochordal process
72
when does neurulation occur
at same time as gastrulation
73
neurulation definition
process of forming neural tube which will form brain and spinal cord
74
steps of neurulation (3)
-ectoderm thickens
-neural place invaginates to form neural groove with neural folds on either side
-neural folds form neural tube
75
ancephaly
-abnormal neurulation
-no/partial brain
-rostral pore doesn't develop properly
76
spina bifida
-abnormal neurulation
-caudal pore doesn't develop properly
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where does neural crest form
between neural tube and ectoderm/epidermis
78
differentiation of mesoderm occurs when
same time as neurulation
79
endoderm goes on to form
gut tube/lining of GI
80
before differentiation, mesoderm was called
intraembryonic mesoderm
81
3 parts of mesoderm
-paraxial
-intermediate
-lateral plate
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paraxial mesoderm
-located near neural tube
-forms somites
83
3 somites (mesoderm)
-dermatome
-myotome
-sclerotome
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dermatome
somite
-forms dermis of skin over dorsal regions
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myotome
somite
-voluntary muscles
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scleratome
somite
-vertebrae, axial skeleton
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intermediate mesoderm
forms gonads and portions of urogenital system
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2 layers of lateral plate mesoderm
somatic and visceral
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somatic lateral plate mesoderm
body wall structures
90
visceral lateral plate mesoderm
smooth muscle of gut
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orientation of somites in mesoderm
outer = dermatome
middle = myotome
inner/medial = scleratome
92
body folding is important for formation of what structure
gut tube
93
2 major folds that transform flat embryonic disc into 3D
-meidan plane
-horizontal place
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median plane body folding
-head and tail folds
-forms allantois
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what does allantois become
membrane that cradles developing fetus
96
allantois is a derivative of what (hint: gut)
hindgut
97
body folding in horizontal plane
-right and left lateral folds
-allantois obliterates extraembryonic coelem
-yolk sac separates from body
98
2 parts of placenta
-fetal part
-maternal part
99
fetal part of placenta derived from
chorionic sac = trophoblast
100
maternal part of placenta derived from
endometrium
101
what separates fetus from endometrium
fetal part of placenta and fetal membranes
102
formation of choriovitelline membrane (first placenta)
fusion between yolk sac (vitelline sac) and chorion
103
definitive yolk sac is continuous with what structure
midgut
104
how are blood vessels developed from extraembryonic mesoderm
blood vessels grow through yolk sac --> penetrate body of embryo --> grow into allantois --> vascularize chorion
105
what happens as choriovitelline membrane recedes
chorioallantoic membrane increases
106
chorioallantoic membrane
membranes that have fused between allantois and chorion
107
placenta type is defined by
number of tissue layers between mother and fetus
108
placental type in horses
epithliochorial
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placental type in cattle
synepitheliochorial
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placenta type in dogs and cats
endotheliochorial
111
simplest placenta type
horses = epitheliochorial
112
most complex placenta type
dogs and cats = endotheliochorial
113
epitheliochorial placenta type
-horses
-endometrial epithelium remains in tact and is apposed to chorionic epithelium
-fetus and maternal parts are pretty separated (least invasive)
114
2 specializations of horse placentation
-chorionic girdle
-endometrial cups
115
chorionic girdle (horses) function
-destroy uterine cells
116
endometrial cups location (horses)
interdigitate in chorionic girdle
117
equine microcotyledons
fetal and maternal microvillous interdigitate (one big digitation)
118
precocial infant
ready to live after birth (horses)
119
cattle synepitheliochorial type
-attenuated layer of combined maternal and fetal epithelium
-union of fetal and maternal cells
-some connection between mother and fetus (but blood supply still separated)
120
union of fetal and maternal cells = what kind of epithelium
cryptal
121
cotyledonary placentation in cattle
placentome = caruncle and cotyledon
caruncle = maternal, stuck to cotyledon on fetus side
cotyledons fit into maternal crypts in caruncles
122
endotheliochorial placenta dogs and cats
-uterine epithelium and connective tissue are removed and chorionic epithelium comes in direct contact with endometrial capillaries (still have separated blood supply)
123
zonary placentation in dogs and cats
no connections on sides because of multiple fetuses
124
altricial infants
need care very early in development (dogs and cats)
125
2 types of twinning in calves
-monozygotic
-diazygotic
126
monozygotic =
one ovum
127
dizygotic =
2 ova
128
65% of monozygotic twinning begins at what stage of embryonic development
blastocyst
129
how monozygotic twins are formed 65% of the time
2 embryoblasts --> 2 amniotic sacs + 1 trophoblast (1 placenta + 1 chorionic sac) --> 2 amnions with single placenta
130
how monozygotic twins are formed 35% of the time
2 morulas --> 2 blastocysts --> 2 amnions, 2 placentas and 2 chorions
131
when does separation occur in monozygotic twins (35% of the time way)
before formation of blastocystic cavity
132
other way monozygotic twins originate
division of embryonic disc in week 2
133
how monozygotic twins originate from embryonic disc
fused embryos --> embryonic disc divides = 2 individuals in 1 amniotic sac --> parasitic twins, conjoined twins or separate twins
134
What kind of placentation do horses use
Diffuse
135
Diffuse placentation
-placenta with villi scattered around surface of chorion (entire surface of chorioallantoic membrane is involved in formation of placenta)
136
Function of microcotyledons in horse (diffuse) placentation
Fundamental unit of fetal-maternal interface
-consist of chorionic villi that invaginate into endometrium
137
what fluid is deep allantoicamniotic membrane
amniotic fluid
138
what fluid is deep to chorioallantoic membrane and superficial to allantoicamniotic membrane
allantoic fluid
139
what membrane attaches to the uterine lumen
chorioallantoic membrane
