Early Embryology Flashcards
(85 cards)
1
Q
When is the egg released from the ovary?
A
14 days into ovarian cycle
2
Q
What is sperm travel from cervix to oviduct?
A
30 mins to 6 days
3
Q
What is the egg coat called?
A
Zona pellucida
4
Q
What is the female nucleus called?
A
Female pronucleus
5
Q
What is the male nucleus called?
A
Male pronucleus
6
Q
3 things that happen during fertilization
A
- Diploid number of chromosomes
- Gender determination
- Cleavage initiated
7
Q
The sperm has to meet the egg cell within ___ hours of ovulation
A
24
8
Q
At what point does the cell become a 2 cell stage zygote?
A
30 hours
9
Q
What is the ball of cells called after the zygote rapidly divide?
A
Morula
10
Q
At what point does cell become a morula?
A
3 days
11
Q
At what point does the morula become an advanced morula?
A
4 days
12
Q
What is the next stage after morula?
A
Blastocyst (fluid filled cavity)
13
Q
When does the blastocyst form?
A
5 days post-fertilization
14
Q
What mass develops in blastocyst?
A
Inner cell mass (embryoblast)
15
Q
When does blastocyst enter uterus?
A
4.5-5 days
16
Q
When does blastocyst implant in endometrium?
A
5.5-6 days
17
Q
Development of embryo occurs at _____ from conception
A
7-8 weeks
18
Q
List types of abnormal implantation *
A
Interstitial
Tubul (isthmus)
Tubal (ampullar)
Infundibular (ostial)
Ovarian
Peritoneal
Cervical
19
Q
At week 1, what tissues are present?
A
Syncytiotrophoblast
Cytotrophoblast
Inner cell mass
20
Q
Syncytiotrophoblast has…
A
Lacunae
21
Q
Tissue of uterine wall is also known as
A
Uterine stroma
22
Q
At week 2, trophoblasts differentiates into 2 layers known as…
A
The cytotrophoblast and Syncytiotrophoblast
23
Q
At week 2, the embryoblast forms 2 layers known as
A
The epiblast and hypoblast
24
Q
At week 2, 2 cavities form known as the
A
Amniotic and yolk sac cavities
25
At week 2, the extraembryonic mesoderm splits into
The somatic and splanchnic layers
26
At day 8, what parts divide?
Trophoblasts
Embryoblast
27
Syncytiotrophoblast region is
Multinucleated bc no cell walls
28
What do Syncytiotrophoblasts produce?
hCG
29
At day 9, what forms?
2 cavities:
Amniotic cavity
Exocoelomic cavity (primitive yolk sac)
30
What in the amniotic fluid is important for amniocentesis?
Sloughed off cells from embryo
31
What procedure do the sloughed off cells from amniotic fluid help us do?
Karyotyping
32
What occurs at day 12?
Extraembryonic mesoderm becomes somatic and splanchnic layers
33
What happens on day 13?
Extraembryonic cavity/chorionic cavity becomes huge but will quickly regress by end of second month
34
At 13 days, what else grows but will quickly regress later?
Yolk sac but by end of second month will regress
35
What part will grow beginning end of second month to end of third month?
Amniotic cavity (holds fetus)
36
At day 13, what could lead a woman to believe she got her period?
You might have a better trophoblastic lacunae that allow blood to come out
37
What occurs at week 3?
Gastrulation
38
What happens in gastrulation?
Converts bilaminar embryonic disc into the trilaminar embryo
39
What are the 3 germ layers produced by gastrulation?
1. Ectoderm
2. Mesoderm
3. Endoderm
40
What’s involved in the ectoderm?
Neural system
Skin
Appendages that relate to external environment (e.g. eyes and ears)
41
What’s involved in the mesoderm?
Musculoskeletal tissue
Limb buds
Genitourinary system
Body wall
Membranes that line cavities
42
What’s involved in the endoderm?
Foregut, midgut, and hindgut
GI Tract and appendages (liver, pancreas)
Respiratory tract
Bladder
43
What is opposite the primitive streak on other side of epiblast?
Oropharyngeal membrane
44
Which side is dorsal? Epiblast or hypoblast
Epiblast is dorsal
45
Epiblast layers migrate through what?
Primitive node and streak
46
What is known as "the organizer" in gastrulation?
The Primitive Node
47
The body plan is redefined during what?
Gastrulation
48
What becomes the future mouth?
Oropharyngeal membrane
49
What becomes the future anus?
Cloacal membrane
50
Teratogenesis is associated with what?
Gastrulation
51
What is holoprosencephaly?
Injury to the anterior (cranial end) midline of germ disc
52
What 2 things are associated with holoprosencephaly?
High dose alcohol
Genetics
53
What is caudal dysgenesis?
Injury to the caudal aspect of the germ disc
54
What 2 things are associated with caudal dysgenesis?
Genetics
Environmental insults
55
What are sacrococcygeal tumors?
Remnant of the primitive streak
56
What can result in conjoined twins?
Splitting of the primitive node
57
List the birth defects associated with gastrulation
1. Holoprosencephaly
2. Cyclopia
3. Caudal dysgenesis (sirenomelia)
4. Sacrococcygeal tumors
5. Conjoined twins (splitting of primitive node)
58
What type of plane divides body into left and right sections?
Sagittal plane
59
What type of plane divides body into front and back sections?
Coronal plane
60
Describe anatomical position
Standing, legs together, feet on floor
Hands at sides, palms facing anteriorly
Head held erect, facing anteriorly
61
what plane divides into upper and lower sections?
Transverse plane
62
List the 6 phases of embryology
1. Gametogenesis
2. Fertilization
3. Cleavage
4. Gastrulation
5. Body plan formation
6. Organogenesis
63
What are the migration patterns when epiblast cells migrate through primitive node and streak?
Caudal to cranial
Medial to lateral
64
Describe the notochord
Mesodermal derivative
Precursor to axial skeleton
Forms nucleus pulposus of intervertebral discs
Vertebral bodies form around notochord
65
Describe somites
Epithelial balls of cells formed in segmental pairs along the neural tube from paraxial mesoderm; differentiate into vertebrae, muscles of the back and body wall, and dermis of the skin
66
Can somites be used to track development?
Yes, can count somites to see how far development has proceeded
67
Describe the 3 step process of neurulation
1. Notochord forms from mesoderm cells soon after gastrulation finishes
2. Signals from notochord cause inward folding of ectoderm at neural plate
3. Ends of neural plate fuse and disconnect to form an autonomous neural tube
68
When does fertilization begin?
At conception
69
When does gestational age begin?
Two weeks earlier, at beginning of last menstrual period
70
Embryology is used using days...
Post-fertilization
71
When may malformation of an embryo occur?
Between weeks 3-8 when organs are forming as it is period of max sensitivity to abnormal development
72
When may functional disturbance of a fetus occur?
Between weeks 8-38 during growth and maturation of organ systems
73
When may death of an embryo occur?
Between weeks 0-3
74
Define birth defect
Term for a congenital malformation
75
Define congenital disorder
A condition existing at birth and often before birth, or that develops during the first month of life, regardless of causation
76
Define teratology
The study of causes and biological processes leading to abnormal development
77
Define teratogen
Any agent that causes a birth defect
78
Define critical period
Time of increased sensitivity
79
What used to be used to decrease nausea/vomitting?
Thalidomide
80
What did thalidomide affect? What did it cause?
Blood supply to arm and forearm bones. Caused phocomelia
81
What are the 4 factors that make one susceptible to congenital anomalies?
Maternal age
Environmental factors
Genetic predisposition
Unknown
82
What happens on day 8?
1. Trophoblast divides to form cytotrophoblasts and syncytiotrophoblasts
2. Embryoblast divides to form hypoblast and epiblast
83
What happens on day 9?
Formation of amniotic cavity and exocoelomic cavity (primitive yolk sac)
84
What happens on day 12?
Extraembryonic mesoderm forms:
extraembryonic splanchnic mesoderm & extraembryonic somatic mesoderm
85
What happens on day 13?
1. Extraembryonic cavity (chorionic cavity) is quite larger right now
2. Yolk sac is also large right now
3. Amniotic cavity is a bit smaller but will grow
4. Trophoblastic lacunae may allow for blood to come out (NOT PERIOD BABES - STILL PREGGO)
