Human Embryogenesis Flashcards
1
Q
the development of a human embryo, which occurs during the early stages of prenatal development
A
human embryogenesis
2
Q
occurs between fertilization and birth
A
prenatal development
3
Q
what are the three periods of prenatal development
A
pre-implantation period
embryonic period
fetal period
4
Q
what time frame does the pre-implantation period occur in
A
1st week
5
Q
what time frame does the embryonic period occur in
A
2nd to 8th week
6
Q
what time frame does the fetal period occur in
A
3rd to 9th month
7
Q
in the pre-implantation period, the zygote forms into a __________
A
blastocyst
8
Q
in the embryonic period, the blastocyst forms into an _________
A
embryo
9
Q
in the fetal period, the embryo forms into a _________
A
fetus
10
Q
disturbances in prenatal development can produce _______ ________
A
birth defects
11
Q
structural or functional disorders that are present at birth
A
congenital malformations
12
Q
when do most congenital malformations occur
A
during embryogenesis
13
Q
when looking at teratogenic sensitivity, if exposure is very early (up to 4 weeks), what happens
A
death of the conceptus
14
Q
when looking at teratogenic sensitivity, if exposure is between 4 and 8 weeks, what happens
A
significant structural anomalies
15
Q
when looking at teratogenic sensitivity, if exposure happens after 10 weeks, what happens
A
the effect may be unnoticed
16
Q
what happens during fertilization
A
egg and sperm unite
17
Q
what is another name for egg and sperm
A
gametes
18
Q
gametes contain _______ the complement of chromosomes found in other human cells
A
half
19
Q
a cell has half the number of chromosomes
A
haploid
20
Q
DNA is divided into _________
A
chromosomes
21
Q
each chromosome contains _________
A
genes
22
Q
a segment of DNA that provides instructions for making a cell
A
gene
23
Q
different versions of the same gene
A
alleles
24
Q
chromosomes 1-22
A
autosomes
25
members of each pair of chromosome are __________
homologous
26
which chromosome is the sex chromosome
chromosome 23
27
somatic cells are produced by _________
mitosis
28
duplicated chromosomes pack and the spindle preps
prophase
29
chromosomes meet in the middle of the cell
metaphase
30
duplicated chromosomes split apart and move to opposite ends of the cell
anaphase
31
two new nuclei form
telophase
32
cytoplasm divides to form two new cells
cytokinesis
33
gametes are haploid and form by _______
meiosis
34
homologous pairs of duplicated chromosomes meet up and then split up during the first division, duplicated chromosomes split apart in the second division
extra division
35
does mitosis or meiosis have extra division
meiosis
36
how is genetic material exchanged in meiosis
crossing over
37
when step of meiosis is occurring when homologous chromosome pairs meet up and exchange genetic material through crossing over
prophase 1
38
does mitosis or meiosis create genetic variance
meiosis
39
how many daughter cells are created in mitosis
2
40
how many daughter cells are created in meiosis
4
41
meiosis in female gametes does not complete until __________
fertilization
42
in females, meiosis pauses at ___________
metaphase II
43
in order for fertilization to occur, what must the sperm do
reach the egg in the ampulla and penetrate the zone pellucida
44
an extracellular matrix surrounding the ovum
zona pelluicda
45
sperm releases enzymes that break down some of the ________ _________, making a path for the sperm
zona pellucida
46
after fertilization, the zona pellucida remains around the ________ until it hatches before implantation
zygote
47
what are the genetic factors that may affect development
aneuploidy, genetic mutations, and structural chromosomal anomalies
48
individual inherits an extra or missing chromosome
aneuploidy
49
individual may inherit an allele with a disease causing mutation from one or both parents
genetic mutations
50
what is an example of an aneuploidy
Down syndrome
51
what is an example of a genetic mutation
apert syndrome
52
caused by errors in DNA replication or environmental factors including DNA damage
structural chromosomal anomalies
53
fertilized egg
zygote
54
are zygotes diploid or haploid
diploid
55
zygote undergoes mitosis and quickly splits into more and more cells without stopping to grow
cleavage
56
when does cleavage occur
preimplantation
57
in preimplantation, the zygote starts to travel to the _________, where it will hatch from the zona pellucida and embed in the cell wall of the uterus
uterus
58
cells in the morula continue to divide, but also start to differentiate and secrete fluid
differentiation
59
the process by which a cell becomes a specific type of cell and specialized in certain functions
differentiation
60
cleavage gives rise to a ball of cells
morula
61
as a result of further division and differentiation, the morula developed into a ________
blastocyst
62
small cluster of cells in blastocysts
embryoblast
63
blastocysts consists of:
embryoblast
blastocoel
trophoblasts
64
a fluid filled space inside of a blastocyst
blastocoel
65
a layer of cells in blastocysts
trophoblasts
66
when does implantation occur
around day 7
67
at the end of the first week, the blastocyst hatches out of the _________ _________
zona pellucida
68
when do trophoblasts attach and invade the lining of the uterine wall
implantation
69
when does the formation of the bilaminar embryo occur
second week
70
when does the embryoblast reorganize into a flat, bilayered disc with the amniotic cavity and yolk sac on either side
during the formation of the bilaminar embryo
71
what are the two cell layers of the bilayered disc
epiblast layer and hypoblast layer
72
tall columnar cells lining facing the amniotic cavity
epiblast layer
73
flat/cuboidal layer facing the yolk sac
hypoblast layer
74
the process by which the bilaminar embryo is converted into a 3-layered trilaminar embryo
gastulation
75
gastrulation involves the migration of some cells in the __________ layer toward the __________ layer
epiblast
hypoblast
76
extends from the caudal end of the developing embryo to about half way toward the cephalic end and ends in the primitive node
primitive streak
77
during gastrulation, cells continue to migrate below the ________ layer
epiblast
78
as a result of gastrulation, the migratory epiblast cells displace the hypoblast layer and form what two layers
mesoderm and endoderm
79
the cells that do not displace to the hypoblast layer and remain in the epiblast become what
the ectoderm
80
what will the ectoderm form
epidermis, salivary glands, and nervous system
81
what will the mesoderm form
bones, cartilage, muscles, connective tissues, lymphatic system, blood cells and cardiovascular system,
82
what will the endoderm form
lining of the digestive tract and respiratory system
83
two areas where there is not a middle layer of mesoderm
oropharyngeal membrane and cloacal membrane
84
what will the oropharyngeal membrane eventually form
mouth
85
what will the cloacal membrane eventually form
anus
86
where in the embryo is the oropharyngeal membrane located
cephalic end
87
where in the embryo is the cloacal membrane located
caudal end
88
in the areas surround the oropharyngeal membrane and cloacal membrane, what happens
ectoderm and endoderm fuse to prevent growth of mesoderm in between
89
some ectoderm cells also migrate from the primitive node towards the cranial end of the developing embryo to form a rod structure called __________
the notochord
90
what is the notochord important for
inducing the formation of a structure called the neural tube in the next stage of embryogenesis
91
when does the formation of the trilaminar embryo take place
around the 4th to 6th week
92
what major events take place after the formation of the trilaminar embryo
the neural tube forms
appearance and migration of neural crest cells
lateral and cephalocaudal folding of embryo
93
formation of the neural tube
neurulation
94
the notochord induces thickening of the __________
ectoderm
95
the neural plate moves down towards the notochord to form the ________ ___________
neural groove
96
margins of groove are raised and are called ________
neural folds
97
neural folds fuse to form a tube beneath the ectoderm called the ________
neural tube
98
the neural tube will give rise to the _________
spinal chord and brain
99
what is a result of the failure of the posterior neural tube closing
spina bifida
100
what is the process that the special cells at the edges of the neural plate undergo called
epithelial to mesenchymal transition
101
what are the cells at the edges of the neural plate called
neural crest cells
102
where do neural crest cells migrate to
mesoderm
103
while the neural tube is forming, the mesoderm is differentiating into what
paraxial mesoderm, intermediate mesoderm, and lateral plate mesoderm
104
paraxial mesoderm adjacent to the neural tube will become _______
somites
