S1_L2: Fertilization, Implantation, and Embryonic Development Flashcards
1
Q
Fertilization is the process by which the sperm & the secondary oocyte fuse in what region of the uterine tube?
A
Ampullary region
2
Q
Widest part of the uterine tube
A
Ampulla
3
Q
TRUE OR FALSE: When sperm enters, it can enter the egg in 30 mins to 5 days.
A
False, it’s 6 days
4
Q
Movement of sperm from the cervix to the oviduct or fallopian tube is accomplished primarily by their own propulsion, although they may be assisted by movements of fluids created by the ___.
A
uterine cilia
5
Q
Only 1% of sperm deposited in the vagina enter the cervix, where they may survive (survival of ~2-3 days). All other sperm die d/t physical stresses. Enumerate the 6 physical stresses.
A
- Ejaculation
- Contractions in female tract
- Change in pH environment
- Mucous secretions
- Defenses of female immune system
- Anatomy of the fallopian tube (narrow or double tract fallopian tube)
6
Q
Life span of sperm in female reproductive tract
A
3 to 7 days
7
Q
What calls and attracts the sperm when the female is ovulating and they automatically swim faster in response?
A
Chemoattractants
8
Q
At ovulation, sperm again become motile, perhaps because of chemoattractants produced by ___, and swim to the ampulla where fertilization usually occurs
A
cumulus cells surrounding the egg
9
Q
Spermatozoa are not able to fertilize the oocyte immediately upon arrival in the female genital tract but must undergo what to acquire this capability?
A
- Capacitation
- Acrosome reaction
10
Q
Glycoprotein coat / shell surrounding the egg that acts as a barrier to the sperm. It facilitates and maintains sperm binding and induces the acrosome reaction.
A
Zona pellucida
11
Q
Capacitation is a period of conditioning of the sperm while in the female reproductive tract that lasts for how long?
A
approximately 7 hours
12
Q
Enumerate the barriers protecting the egg
A
- Corona radiata
- Zona pellucida
- Plasma vitelline membrane
13
Q
Most important coat of the egg that protects inner organelles. It can stop or reject the other sperm to enter and only allows 1 sperm to get in.
A
Zona pellucida
14
Q
TRUE OR FALSE: If no fertilization occurred, progesterone increases and sloughs off and menstruation occurs.
A
False, progesterone decreases
15
Q
After reaching the ___, the sperm become less motile and cease their migration.
A
Isthmus
16
Q
narrowest part of the fallopian tube
A
Isthmus
17
Q
Duration of the trip from cervix to oviduct or fallopian tube in fertilization
A
Minimum of 2 to 7 hours
18
Q
In fertilization, what will prepare the uterus and increase progesterone that causes the thickened uterine wall to develop the characteristics needed for implantation?
A
Luteinizing hormone
19
Q
During what period will the glycoprotein coat and seminal plasma proteins be removed from the plasma membrane that overlies the acrosomal region of the spermatozoa?
A
Capacitation
20
Q
TRUE OR FALSE: Only capacitated sperm that reach the egg can pass through the corona radiata cells and undergo the acrosome reaction.
A
True
21
Q
TRUE OR FALSE: Only one sperm can be capacitated, thus allowing it to penetrate the egg and impregnate.
A
False, more than one
22
Q
What enters the sperm and hyperpolarize the sperm’s plasma membrane, thus affecting the motility of the sperm?
A
Bicarbonate ions
23
Q
The acrosome reaction is induced by?
A
Zona proteins
24
Q
This reaction culminates in the release of enzymes needed to penetrate the zona pellucida
A
Acrosome reaction
25
Enzyme that assists in penetration of the corona radiata barrier (1st layer)?
Hyaluronidase
26
What are the two enzymes that help to penetrate the zona pellucida (2nd layer)?
1. Trypsin-like substance
2. Acrosin
27
Enzyme that is needed for digestion of the zona pellucida (2nd layer)?
Trypsin-like substance
28
Determine the structures derived from the germ layers (in the embryo)
1. Notochord
2. Epithelial lining of digestive and respiratory tracts
3. Epidermis of skin
4. Pancreas
5. Nervous system
6. Musculoskeletal system
A. Endoderm
B. Mesoderm
C. Ectoderm
1. B
2. A
3. C
4. A
5. C
6. B
29
Determine the structures derived from the germ layers (in the embryo)
1. Cornea and lens of eye
2. Liver
3. Lining of urethra and bladder
4. Circulatory system
5. Lining of reproductive system
6. Muscular layer of stomach, intestine, etc.
A. Endoderm
B. Mesoderm
C. Ectoderm
1. C
2. A
3. A
4. B
5. A
6. B
30
Type of pregnancy where the embryo/fertilized egg implants and grows outside of the uterus.
Ectopic pregnancy
Additional: In this case, the mother will have a hard time giving birth or the baby may die inside the fallopian tube. As the embryo grows bigger and bigger, the fallopian tube will burst.
31
Condition where the embryo implants in the inferior portion of the uterus and the placenta can potentially grow over the opening of the cervix.
Placenta previa
32
Enumerate the phases of fertilization
1. Penetration of the corona radiata
2. Penetration of the zona pellucida
3. Fusion of the oocyte and sperm cell membranes
33
The initial adhesion of sperm to the oocyte is mediated in part by the interaction of (1)___ on the oocyte and their ligands, (2)___, on sperm
1. integrins
2. disintegrins
34
Permeability of the zona pellucida changes when the head of the sperm comes in contact with the oocyte surface. This contact results in release of lysosomal enzymes from the cortical granules lining the ___ of the oocyte.
plasma membrane
35
The egg is arrested in which phase of meiosis II?
Metaphase II
36
How many spermatozoa are deposited in the vagina during intercourse?
2-5 million
37
In fertilization, only one sperm enters and the rest engage in disintegration of 3 barriers around the secondary oocyte via what enzyme?
hyaluronidase
38
TRUE OR FALSE: When one sperm enters, the female barriers change and the rest of the male sperm make sure that no other sperm can enter the egg.
True
39
Spermatozoa may remain viable in the female reproductive tract for how long?
48 to 72 hours
-This is the life span of sperm in the female
40
What initiates capacitation of the sperm?
Reproductive tract of the female
41
The acrosome reaction occurs after binding to the ___.
Zona pellucida
42
TRUE OR FALSE: Once a sperm enters the egg, the others will be blocked off because zone 2 will be impermeable.
True
43
Of the 2 to 5 million spermatozoa deposited in the female genital tract, how many reach the site of fertilization?
Only 300 to 500
Additional: Only 1 of these fertilizes the egg. It is thought that the others aid the fertilization sperm in penetrating the barriers protecting the female gamete.
44
Up to which of the 5 zones of the zona pellucida will the sperm be able to penetrate?
Zone 3
45
Both binding and the acrosome reaction are mediated by the ligand ___, a zona protein
ZP3
46
Release of ___ allows sperm to penetrate the zona, thereby coming in contact with the plasma membrane of the oocyte
acrosomal enzymes (acrosin)
47
The acrosomal enzymes alter properties of the zona pellucida to prevent sperm penetration. This process is known as?
zona reaction
48
Because the plasma membrane covering the acrosomal head cap disappears during the acrosome reaction, actual fusion is accomplished between the oocyte and the membrane that covers the ___ region of the sperm head.
posterior
49
TRUE OR FALSE: In humans, both the head and tail of the spermatozoon enter the cytoplasm of the oocyte, but the plasma membrane is left behind on the oocyte surface.
True
50
penetration of more than one spermatozoon into the oocyte
polyspermy
51
Enumerate the reactions that prevent polyspermy
1. Cortical reaction
2. Zona reaction
52
As the spermatozoon enters the oocyte, the release of cortical oocyte granules occurs, which contain ___ enzymes. Then, the oocyte membrane becomes impenetrable to other spermatozoa.
lysosomal
53
The oocyte finishes its ___ meiotic division immediately after entry of the spermatozoon.
second
54
The chromosomes (22+X) of the definitive oocyte (a result of meiosis 2) arrange themselves in a vesicular nucleus known as the ___.
female pronucleus
55
TRUE OR FALSE: The male and female pronuclei are both haploid and replicate its DNA. Chromosomes organize in the spindle in preparation for normal mitotic division.
True
56
TRUE OR FALSE: A result of fertilization is the restoration of the diploid number of chromosomes, half from the father and half from the mother. Thus, the zygote (fertilized ovum) contains a new combination of chromosomes different from both parents.
True
57
a Y-carrying sperm produces a ___ embryo
male (XY)
58
TRUE OR FALSE: The chromosomal sex of the embryo is determined at fertilization.
True
-We just can't know it yet because it's happening inside the fallopian tube
59
TRUE OR FALSE: Initiation of cleavage is a result of fertilization.
True
Note: Without fertilization, the oocyte usually degenerates 24 hours after ovulation.
60
After fertilization, mitosis occurs. After mitosis, cleavage occurs.
A. Only the 1st statement is true
B. Only the 2nd statement is true
C. Both statements are true
D. Both statements are false
C. Both statements are true
61
Once the zygote has reached the two-cell stage, it undergoes a series of mitotic divisions, which increases the numbers of cells. This process is known as?
cleavage / segmentation
62
The cells formed as a result of cleavage become smaller with each cleavage division. These cells are known as?
blastomeres
63
Until the ___ stage of embryonic development, the blastomeres form a loosely arranged clump
eight-cell
64
After the (1)___ cleavage, blastomeres maximize their contact with each other, forming a compact ball of cells held together by tight junctions. This process, known as (2)___, segregates inner cells, which communicate extensively by gap junctions, from outer cells.
1. third
2. compaction
65
The 16-cell morula (mulberry) is formed from continuous division on Day __ after fertilization.
4
End product: 16 blastomeres
66
The inner cell mass of the morula give rise to (1)___ proper, while the outer cell mass forms the (2)___
1. tissues of the embryo
2. trophoblast
67
A method used to count the days of ovulation, with 14 days of infertility after a woman’s menstrual period
Rhythm / Calendar method
68
It prevents pregnancy if it was taken 120 hours after sexual intercourse. A high dose of progestin is the result of taking this.
Emergency Contraceptive Pill (ECP)
69
Differentiate vasectomy from tubal ligation
Vasectomy: Cut the vas deferens
Tubal ligation: Tie the fallopian tube
70
It releases progestin that causes thickening of cervical mucus. It makes the sperm less active and have difficulty entering the egg.
Hormonal Intrauterine device (IUD)
71
It releases copper to the uterus preventing fertilization or inhibits attachment of fertilized egg to the uterine wall, prevent sperm from entering uterine tubes.
Copper Intrauterine device (IUD)
Note: When a couple has sex, they will still not be able to produce an offspring. It will only implant but cannot fertilize.
72
The use of condoms containing spermicides and female condoms lining the vagina is known as ___
Barrier method
73
When estrogen or progestin levels are low, what hormones will release a follicle egg and thus, the menstrual flow occurs?
Follicle Stimulating Hormone and Luteinizing Hormone
74
TRUE OR FALSE: When estrogen or progestin levels are high, FSH and LH will not be released. The female will not have the monthly period or may have a delayed period.
True
75
What hormones can inhibit ovulation by preventing the release of FSH and LH from the pituitary gland, changing the lining of the uterus, and thickening the cervical mucus, thus making it difficult for sperm to enter uterus?
Estrogen and/or
Progestin
76
Changes in the fetus during the ff months of prenatal development
1. Lanugo begins to fall off
2. Nearly all of the vernix and lanugo are gone
3. Eyes and eyelids fully formed
4. Start of 3rd Trimester
5. Cerebral Cortex of the brain rapidly develops
A. 6th month
B. 7th month
C. 8th month
D. 9th month
E. 10th month
1. C
2. E
3. A
4. C
5. B
77
Changes in the fetus during the ff months of prenatal development
1. Fat developing under skin
2. Vernix is present
3. Fingernails extend beyond the fingertips
4. Crown Rump Length is about 7-8 inches
5. Fetus has a firm grasp
A. 6th month
B. 7th month
C. 8th month
D. 9th month
E. 10th month
1. A
2. D
3. C
4. A
5. E
78
Changes in the fetus during the ff months of prenatal development
1. Taste buds begin to form
2. Subcutaneous fat is stored for later use
3. Eyes have developed enough to constrict and dilate
4. Bone marrow begins making blood cells
5. Lanugo is shed
A. 6th month
B. 7th month
C. 8th month
D. 9th month
E. 10th month
1. A
2. C
3. D
4. A
5. D
79
Changes in the fetus during the ff months of prenatal development
1. Hair begins to grow, hair is thin
2. Arms bend at elbows
3. Bones begin hardening
4. The heart has formed and begins to beat faintly
5. Gender of the fetus may be determined
A. 2nd month
B. 3rd month
C. 4th month
D. 5th month
1. C
2. A
3. B
4. A
5. D
80
Changes in the fetus during the ff months of prenatal development
1. Begins making spontaneous movements
2. Fingers and toes develop
3. Sex organs are fully formed
4. (Embryonic) tail disappears
5. Ears and nose begin to develop cartilage
A. 2nd month
B. 3rd month
C. 4th month
D. 5th month
1. B
2. A
3. C
4. A
5. D
81
Changes in the fetus during the ff months of prenatal development
1. Heart and blood vessels are fully formed
2. The sex organ are the same in all embryos
3. Can suck a thumb, yawn, stretch, make faces and grasp.
4. Digestive organ begins to function
5. Embryo develops into a fetus
A. 2nd month
B. 3rd month
C. 4th month
D. 5th month
1. C
2. A
3. D
4. B
5. B
82
Changes in the fetus during the ff months of prenatal development
1. Fingernails and toenails begin to appear.
2. Kidneys start making urine
3. External ears, eyes, eyelids, liver, and upper lip had begun forming
4. Head is more erect
5. Posture becomes less curled and more upright
A. 2nd month
B. 3rd month
C. 4th month
D. 5th month
1. D
2. B
3. A
4. C
5. B
83
The embryo develops into a fetus after ___ weeks
10
84
The sex organ are the same in all embryos until the ___ week.
7th or 8th
85
A greasy biofilm material (white-cheesy substance) that covers and protects the skin of the fetus starting at the 5th month of prenatal development
Vernix caseosa
Note: When born, it is still on the baby
86
A fetus is extremely preterm when born at or before ___ weeks of pregnancy.
25
87
Final and longest phase of prenatal development
Period of the fetus
88
Fetus responds to touch at (1)___ weeks and responds to light at (2)___ weeks
1. 14
2. 26
89
Fetus responds to (1)___ at 29 weeks, can distinguish (2)___ at 34 weeks
1. sound
2. different speech sounds
90
TRUE OR FALSE: Fetus can learn and remember when exposed to distinct sounds such as mother’s voice or distinct taste.
True
91
The length from top of the head to bottom of buttocks
Crown Rump Length
92
TRUE OR FALSE: On average, the neonate (newborn) is around 18-22 inches long and weights around 7-8 pounds.
True
93
By (1)___ to (2)___ weeks, most systems function well enough that a fetus born at this time has a chance to survive (age of viability).
1. 22
2. 28
94
Fetal orientation in the womb
Fetal position
95
Refers to which part of the fetus is leading/closest to the birth canal
Fetal presentation
96
TRUE OR FALSE: A fetus facing backward is in the abnormal position.
False, it should be facing forward
97
Fetal presentation where the feet are leading / closest to the birth canal
Breech presentation
98
The spermatozoa travels via uterine contraction and the oocyte travels via the ___ and rhythmical contraction of muscle of tube to reach the ampulla.
ciliary beat
99
In male fetus, testes begin to descend into scrotum by 30th-34th week, completing on the ___ week.
40th
100
fine, downy hair that covers the body of the fetus
Lanugo
101
The eyelids are usually fused together until the ___ week
28th
102
Period where blastocytes are already imbedded
Week 2
-Week of pairs / doubles
103
Period of the formation of 3 germ layers (endoderm, mesoderm, ectoderm), 3 important structures (primitive streak, notochord, neural plate), and the 3 layered chorionic villi
Week 3
104
The period of the embryo spans how many weeks?
Weeks 3-8
105
Gestational age starts on the ___ of a woman’s last menstrual period (LMP).
first day
Note: Women are pregnant for about 9 months, but because pregnancy is measured from a woman’s last menstrual period, a full-term pregnancy usually totals about 10 months.
106
TRUE OR FALSE: All major organs and organ systems are formed during the period from 4th to 8th week.
True
2nd month is known as the Period of Organogenesis
107
Known as the critical period in pregnancy where the embryo is most susceptible to factors interfering with development and congenital malformations
Second month
108
Time when the three germ layers (ectoderm, mesoderm, and endoderm) give rise to a number of specific tissues and organs. The development of the nervous system also occurs.
3rd-8th week (Embryonic period)
109
The period of the fetus spans how many weeks?
Weeks 9-38
110
Trophoblast secretes ____ that directs the corpus luteum to survive, enlarge, and continue producing progesterone and estrogen to suppress menses, thus causing pregnancy symptoms
hCG or human chorionic gonadotropin hormone
111
It creates an environment suitable for developing embryo and accumulates in the maternal blood stream. It is excreted in the urine.
hCG or human chorionic gonadotropin hormone
112
For the pregnancy test result to be accurate and correct, when should the test be done?
After the 2nd week
113
The process that the epiblast and hypoblast undergo, where 2 cell layers become 3 germ cell layers
Gastrulation
114
The blastocele is a single cavity formed from the entering of fluid into the intercellular spaces of the inner cell mass, which become confluen. It eventually becomes the ___.
yolk sac
115
The cells of the inner cell mass are known as the (1)___ and those of the outer cell mass, known as (2)___, flatten and form the epithelial wall of the blastocyst.
1. embryoblast
2. trophoblast (This later contributes to the placenta and plasma membrane)
116
Day 3 of transitioning from cleavage to blastomere is the ___ stage
8-cell
117
Day 2 of transitioning from cleavage to blastomere is the ___ stage
4-cell
118
Integrin receptors for (1)___ promote attachment of the trophoblast, while integrin receptors for (2)___ stimulate migration.
1. Laminin
2. Fibronectin
119
Process of the blastocyst (embryo) embedding/adheres into the endometrial lining (wall) of the uterus in Week 2
Implantation
Note: It is by this adhesion that the embryo receives oxygen and nutrients from the mother to be able to grow. The blastocyst will adhere to the FUNDUS of the uterus.
120
At what day does the the zygote become a blastocyst?
Day 5
121
The cells of the epiblast migrate in the direction of the primitive streak to form the mesoderm and the intraembryonic endoderm. This inward movement is known as?
Invagination
122
Source of all 3 germ layers in the embryo
Epiblast
123
Inner layer of mononucleated cells that came from the trophoblast
Cytotrophoblast
124
Outer multinucleated zone without distinct cell boundaries that digests endometrial cells to firmly secure the blastocyst into the uterine wall
Syncytiotrophoblast
Note: Syncytiotrophoblasts are in sync with the endometrial lining. Gas and blood exchange starts to support the embryo.
125
A layer (from embryoblast) of small cuboidal cells adjacent to the blastocyst cavity.
hypoblast layer
126
A layer (from embryoblast) of high columnar cells adjacent to the amniotic cavity.
Epiblast layer
127
At the 2nd week, a small cavity appears within the epiblast that enlarges to become the ___.
Amniotic cavity
128
Epiblast cells adjacent to the cytotrophoblast are called ___. Together with the rest of the epiblasts, they line the amniotic cavity.
Amnioblasts
129
TRUE OR FALSE: At the 2nd week, the blastocyst is partially embedded in the endometrial stroma. The endometrial stroma adjacent to the implantation site is edematous and highly vascular.
True
Additional: The large, tortuous glands secrete abundant glycogen and mucus.
130
The primitive yolk sac is a cavity that formed on the side of the ___.
Hypoblast
