L12-L15 Embryology Flashcards
1
Q
What does the released ovum do next?
A
The ovum is released, leaves behind follicular cells, and structure forms from the original follum
2
Q
Where there is 1 parent sperm, there is ___ baby sperms
A
Four baby sperms
3
Q
What is a zona pellucida?
A
A glycoprotein coat
4
Q
What makes up a corona radiata?
A
Zona pellucida + layers of follicular cells
5
Q
What does the zona pellucida + layers of follicular cells make up?
A
Corona radiata
6
Q
Sperms must undergo ____
A
Capacitation
7
Q
What is capacitation?
A
The process by which acrosomal cap is degraded
8
Q
Cats, Dogs, Cattle, Horses- site of sperm deposition for each?
A
Vagina, Uterus, Vagina, Uterus
9
Q
The sperm MUST pass through the _______
A
Corona radiata
10
Q
Location of fertilization is species- specific, usually in the ____.
A
Oviduct
11
Q
What does the cilia aid in?
A
Helps fertilize ovvum
12
Q
What does the zona pellucida do once one sperm cell passes through?
A
Hardens
13
Q
Sperm in the oocyte without its plasma membrane causes ____ ?
A
Zona reaction, which makes the oocyte impenetrable to other sperms
14
Q
After the oocyte completes the second meoitic division and the ______ is formed
A
Female pronucleus
15
Q
What is a blastomere?
A
New embryonic cell
16
Q
What is cleavage? What is unique about this?
A
Mitotic division- rates are species-specific
17
Q
What is unique about 4-cell stage?
A
Blastomeres get smaller with each division
18
Q
What is a morula?
A
A superficial layer around a central core of cells
19
Q
Each cell has potential to become baby parts- how many cells about to do this?
A
8-16 cells
20
Q
Formation of the morula- how many during cleavage?
A
4-cell
21
Q
What happens during the formation of the blastocyst?
A
The blastocystic cavity appears, formed by secretions from the blastomeres
22
Q
The blastocystic cavity does what?
A
Separates the blastomeres into parts
23
Q
The trophoblast does what?
A
Forms the embryonic layers of the placenta
24
Q
The trophoblast cells are those that are _______.
A
Joined by tight junctions to protect the embryoblast
25
The blastocysts emerges from the ______?
Zona pellucida
26
Hypoblast emigrates to enclose the _____.
Blastocystic cavity (=exocoelmic cavity)
27
At the stage of embryoblast and trophoblast, the large cavity is called the _______.
Blastocystic cavity
28
When the hypoblast begins to form at the ventral surface of the embryoblast, the cavity is called the ______.
Exocoelomic cavity
29
When the hypoblast extends to surround the exocoelomic cavity, the cavity is called the ____________.
Primitve yolk sac
30
What does the bilaminar embryonic disc do?
Epiblast forms tight junctions + replace Rauber's layer
31
Bilaminar embryonic disc is composed of what two things?
Epiblast + Adjacent hypoblast
32
What species of animals undergo single conceptus?
Cattles and horses
33
Single conceptus in a cattle?
Implantation in the upper half of the uterine horn adjacent to the ovulating ovary
34
Single conceptus in horses?
Blastocyst will travel between horsn and implantation placement is random
35
What species of animals are polytocous?
dogs and cats
36
In polytocous species, what is significant?
Blastocysts are evenly placed in both horns- mechanism is unknown
37
What is a mesometrium?
Ligament that holds uterus to the side of the body wall
38
Primitive yolk sac pinches off and definitive ____ is formed.
Yolk sac
39
Cells emigrate from the epiblast to form ____.
Amniotic membrane
40
Prechordal plate is?
When some anterior cells of the hypoblast become columnar and form this thickened circular area
41
What is the prechordal plate ultimately the position of?
Mouth!!
42
Gastrulation begins with primitive streak, which is?
Appears from caudal to cranial in the medial plane on the dorsal aspect of the embryonic disc
43
What is estrus?
When females are sexually receptive
44
Where is the primitive groove located in?
Primitive streak
45
What are the three germ layers?
1. Ectoderm
2. Mesoderm
3. Endoderm
46
What is the bilaminar made of? (2 components)
Epiblast + hypoblast
47
What does the hypoblast NOT become part of?
The fetus
48
What does the notocord gives us?
Stiffniss/ rigidity
49
**What is Gastralation?**
Causes mesoderm, ectoderm, endoderm to fuse
50
What makes up the trilaminar disc?
Ectoderm, mesoderm, endoderm
51
What is the function of the notochord? (4)
1. Defines the axis of the embryo
2. Provides rigidity
3. Indicates the future site of vertebral bodies
4. Is an important inducer of future structures
52
What is the very first structure to get created?**Also, what is it also called?
Notochord. Primary inducer
53
What occurs during neurulation?
The neural plate invaginates to form the neural groove with neural folds on either side
54
The neural folds about to fuse to form _____? (2 words)
Neural tube
55
What body part does the caudal neuropore develop in the fetus?
Spinal cord
56
Clinical: What happens when there is abnormal neurulation? What is it?
Anencephaly- partial absence of the brain
57
What are the 2 types of spina bifida?
1. Spina bifida occulta
| 2. Spina bifida cystica
58
What is Spina bifida occulta?
A defect in the vertebral neural arch; often undetected
59
What is the Spina bifida cystica?
Herniation of neural tissues and meninges; more serious
60
**What is it that makes us vertebrates? (test q..3 words)**
Neural crest formation makes the tissue that makes us vertebrates
61
What are the steps of neural crest formation?
Neural folds approach each other to turn the neural groove into a neural tube
62
What is the differentiation of mesoderm?
Gives rise to skeleton, muscles, blood, blood vessels, mesenteries, plurae, and urogenital structures
63
Mesoderm develops into 3 parts, concurrent with neuralation:
1. Paraxial mesoderm
2. Intermediate mesoderm
3. Lateral plate mesodern
64
What does the intermediate mesoderm develop into?
Develops into the gonads and portions of urogenital system
65
What does the paraxial mesoderm develop into?
Develops into somites, including dermatome, the myotome, and the sclerotome
66
What does the lateral plate mesoderm develop into?
Develops into the body walls, appendicular skeleton, and the blood vessels
67
The paraxial mesoderm forms somites, which include 3 parts- what are they (also describe)?
1. Dermatome- dermis of skin over dorsal regions
2. Myotome- all voluntary muscles of the head, trunk, and limbs
3. Sclerotome- vertebrae, portions of the neurocranium, and the axial skeleton
68
What does the intermediate give rise to?
It gives rise to the gonads and portions of urogenital system
69
What does the lateral plate mesoderm develop into?
It develops into part of the body walls, primordial heart, appendicular skeleton, blood and blood vessels
70
What two layers does the lateral plate mesoderm divide into? (Also their other names)
1. Visceral (splanchnic) layer
| 2. Parietal (Somatic) layer
71
What is the primary derivative of the endoderm?
Lining of the GI tract
72
What is body folding important for?
The early formation of the gut tube
73
What are the two major folds that transform the flat embryonic disc into three dimensions?
1. Median plane
| 2. Horizontal plane
74
What is the outside portion of the yolk sac?
Extra-embryonic coelom
75
What are the two body folds in the median plane?
1. Head fold
| 2. Tail fold
76
Which part will get pinched off of the amniotic sac with the fetus?
Yolk sac
77
What are the folds in the horizontal plane?
Right and left lateral folds
78
What is the smooth muscle of the gut?
Visceral layer of the lateral plate mesoderm
79
There are two parts of the placenta- what are they and describe?
1. Fetal part- develops from chorionic sac
| 2. Maternal part- derived from the endometrium, lining of the uterus
80
The fetal part of the placenta and the fetal membranes separate what?
The fetus from the endometerium
81
What is unique about fetal membrane organization?
Species-specific
82
What is the first step of development of the first placenta?
The formation of the choriovitelline membrane
83
Where is blood vessel development from?
Extraembryonic mesoderm
84
What are steps of blood vessel growth?
They grow through the yolk sac -> penetrate the body of embryo -> grow into the allantois -> vascularize chorion
85
As the choriovitelline membrane ___, the chorioallatoic membrane ___.
Receeds, increases
86
What are placenta type defined by?
The number of tissue layers between mother and fetus
87
What are the placenta types (from simplest to most complex +animals it relates to)? (4)
1. Epitheliochorial (horses)
2. Synepitheliochorial (cattle)
3. Endotheliochorial (dogs N cats)
4. Haemochorial (humans)
88
What is the epitheliochorial type of placenta?
Endometrial epithelium remains intact and is apposed to the chorionic epithelium
89
What does the chorionic girdle destroy?
Uterine cells
90
What are equine microcotyledons?
Fetal and maternal microvillous interdigitate
91
Horse young conceptus is composed of what? (inside -> out)
1. Yolk sac, 2. chorionic girdle, 3. allatotochorion
92
What is the synepitheliochorial type of placenta?
An attenuated layer of combined maternal and fetal epithelium. Union of fetal and maternal cells: CRYPTAL epithelium
93
Placentome is composed of what two structures?
Cotyledone + caruncle
94
What are cotyledons?
Fit into maternal crypts in the caruncles
95
What is the endotheliochorial placenta type?
Uterina epithelium and connective tissue are removed and the chorionic epithelium comes in direct contact with endometrial capillaries
96
Which species of animals has the zonary placentation?
Dogs and Cats
97
What is significant about the cytotrophoblast and syntitiotrophoblast despite the fact that they are next to each other?**
Separates the maternal and fetal blood
98
What are carnivorans-altricial infants?
Immature born
99
What is the haeomochorial type of placent?
Uterine epithelium and connective tissue are removed and the chorionic epithelium comes in direct contact with maternal blood
100
What is the difference between monozygotic twins and dizygotic twins?
Monozygotic is one ovum
| Dizygotic is two ova
101
The monozygotic twinning usually begins in the ______ stage.
Blastocyte
102
________ of placental vessels and arteriovenous communication between circulatory systems of twins
Anastomosis
103
65% Monozygotic twinning: what does the placenta/sacs look like? (how many)
One placenta
One chorionic sac
Two amniotic sacs
104
35% Monozygotic twinning: what are they composed of? (how many)
2 amnions
2 chorions
2 placentas
105
In the 35% of the monozygotic twins type, separation occurs before ________________________?
The formation of the blastocystic cavity
