EMBRYO Flashcards
1
Q
What stage of development is the oocyte arrested at?
A
Second stage of meiosis
2
Q
What are the three mechanisms by which the oviduct guides the sperm to the oocyte
A
- Chemotaxis
- Thermotaxis
- Rheotaxis
3
Q
How is the sperm guided by chemotaxis
A
cumulus cells of oocyte release progesterone 4 which acts as a chemoattractant
4
Q
How is the sperm guided by rheotaxis
A
The sperm face towards the oncoming current of the oviductal fluid - rotation of the flagella upon CatSper activation
5
Q
How is the sperm guided by thermotaxis
A
The sperm move towards the warmer 39 degree ampulla (sensors for this are TRPM8 and GPCR opsins)
6
Q
How does the oviduct act as a reservoir to sperm
A
When sperm reaches the isthmus they temporarily bind to epithelial cells here and linger until ovulation occurs - where they are released and swim to the oocyte
- apical microvilli have a gamete specific response involving signal transduction, calcium decreases and PH increases to prevent capacitation, decreased motility
7
Q
How are oocytes transported in the oviduct
A
- ovulated oocyte picked up by fimbrae
- passes to ampulla
- propulsive contractions and oviductal cilia beat to move it forward
8
Q
Pacemaker activity in which cells regulates oviduct motility
A
cells of Cajal
9
Q
What are the two stages of sperm maturation in the female tract
A
- capacitation
2. acrosome reaction
10
Q
What happens to the sperm during capacitation
A
- stripping of glycoprotein coat and seminal plasma proteins
- hyperactivity of sperm initiated
11
Q
How does the uterus aid in capacitation
A
- secreted proteolytic enzymes
- has cholesterol binding sinks
12
Q
Which receptors does sperm bind to on the zona pellucida
A
- ZP2/3/4
13
Q
describe the acrosome reaction
A
- sperm binds to zona pellicuda - ZP3/ZP4
- galactose from ZP3 reacts with galactosyltransferase, a cell membrane protein in the anterior end of the sperm head
- increased calcium
- preacrosin binds to ZP2
- induces release of enzymes trypsin and across
- Acrosin digests zona pellucida
14
Q
How is polyspermy prevented after fertilisation
A
- increase of intracellular calcium in egg caused by
sperm binding to egg causes cortical reaction whereby cortical granules are released from the egg which cross-links the zona pellucida proteins - enzymes released from granules - ovastacin cleaves ZP2 - ZP2f which stops preacrosin binding and production of acrosin
- Beta-hexosaminidase B digests oligosaccharide receptor on ZP3
- egg sheds JUNO receptors for sperm membrane (IZUMO 1)
15
Q
What is the metabolism mechanism of the oocyte in the early stages?
A
oxidative metabolism - pyruvate and lactate used to provide energy and as a substrate for the krebs cycle - provided by the oviduct and cumulus cells
16
Q
What is the metabolism mechanism of the oocyte in the late stages?
A
glycolytic metabolism - oviduct provides the glycogen used as an energy source - Amylase then converts this glycogen to glucose (glycogenolysis)
17
Q
List the roles of the oviduct in embryo development
A
- protection against stress and immune responses
- provides energy for metabolism - glucose and pyruvate
- secretes embryotrophic factors
- mitochondrial maturation
- embryo transport
- transport of sperm - via rheotaxis, chemotaxis, thermotaxis
18
Q
Which embryotrophic factors does this oviduct provide
A
- IGF
- FGF
- TGF
- EGF
19
Q
How does the oviduct protect the embryo against stress
A
- oviductal antioxidants reduce oxidative stress in oocytes and embryos
- epithelial cells produce heat shock protein family (HSP25 and 70) to handle heat stress
- Oviductal fluid contains catalase, superoxide dismutases (SOD1/2) and glutathione peroxidase (GPX4) to reduce stress from ROS
- protects embryo agains their own immune system by inhibiting production of antimicrobial peptides and excess protease activity (e2/esr1 signalling)
20
Q
what is the role of the oviduct in embryo transport
A
- tubal muscle contraction
2. motility of ciliated epithelial cells - increased fluid secretion and flow, ciliary beat frequency
21
Q
what is the affect of IGF-1 on the ovary
A
Follicle
- synergise with FSH and LH
- stimulate oestrodial promoting follicle and oocyte growth
Corpus Luteum
- synergise with LH
- stimulate progesterone
- promotes embryo growth and development
22
Q
Put the following stages of preimplantation development in order: Blastulation Syngamy Fertilisation Expansion Hatching Compaction Cleavage Mitotic divison
A
- Fertilisation
- Syngamy
- Mitotic Division
- Cleavage
- Compaction
- Blastulation
- Expansion
- Hatching
23
Q
what is syngamy
A
- cytoplasmic contents of -the sperm cell membrane pass into oocyte cytoplasm - COMPLETING FUSION
- haploid chromosomes from egg and sperm become surrounded by membranes - forming pronuclei
- both sets of chromosomes synthesise DNA in preparation for the first mitotic division
- membranes then break down and mitotic metaphase spindle forms
24
Q
what is cleavage
A
ooplasm divides into two equal halves and successive cleaves increase cell number - one cell zygote becomes two cell conceptus
25
what is compaction
cells flattening and maximise intercellular contents
| cell-cell adhesion increases and outer cells become polarised
26
how is the process of compaction driven
Compaction is Ca2+ dependent.
| E cadherin - cell-cell adhesion molecule drives compaction - through activation of Pk-C
27
What is blastulation
formation of blastula from morula
28
what is blastulation dependent on
- Na/K ATPase confined to the basolateral membrane domains of the trophoectoderm.
- Establishes a trans-trophectoderm ion gradient that facilitates movement of water across the epithelium,
- expands the embryo
29
what is progesterones role preimplantation
- proliferation of the uterine lining
- vascularisation of the endometrium - decidualization
- promotes myometrial quiescence - stops contractions of uterus
- increases maternal ventilation
- promotes glucose deposition in fat stores
30
list the stages of implantation
orientation
apposition
adhesion
invasion
31
what is the maternal to zygotic transition and when does it occur
the period during which zygotic genes are activated and maternal transcripts are cleared
occurs between two cell stage and morula stage
32
what are the essentials for implantation
- healthy embryo
- receptive endometrium
- communication between mother and baby
33
what makes up a receptive endometrium
- shortening of microvilli
- loss of negative surface charge
- thinning of the mucin coat
- formation of pinopodes
34
what is apposition
lining up of trophoblast to endometrium via chemical signalling - causes further decidualisation of the storm
35
what is attachment/adhesion and how does this happen
- binding of conceptus to endometrium
- switch off mucin 1 (thinner endometrium)
- switch on LIF (promotes luminal epithelial receptivity to attachment and signalling from blastocyst)
- HB-EGF binds to conceptus causing it to shed the zona then assists attachment process
36
how is invasion of conceptus facilitated
- molecular messages
- MMP's digest stomal components - kept from doing too much by tissue inhibitors of MMP's or TIMPS
- following attachment there is a "pro inflammatory endometrial reaction" due to prostaglandins, facilitated by Cox2
- VEGF - stimulate angiogenesis
- interleukin 11 associated with decidualization
37
when is the window of implantation
cycle day 19-23 or day 6 post fertilisation
38
what is decidualization
- transformation of endometrial stromal fibroblasts into specialised secretory decidual cells
- post ovulatory process of endometrial remodelling in preparation for pregnancy
- influx of specialised NK cells
- vascular remodelling
39
how do decidualized stromal cells help stop rejection of the embryo
- regulate trophoblast invasion
- resist inflammatory and oxidative insults
- dampen local maternal immune responses
40
what is tolerance
- the mechanism by which embryo is not rejected by the mother and development of an immunologically distinct organism
- reducing the negative impact of the pathogen on individual without actually fighting it ( in this instance pathogen is baby)
41
what happens to NF-Kappa B during implantation
- increase and activate IL6 and IL8 which stimulate migration and invasion
- regulate MMP's to destroy maternal spiral arteries
42
what happens to the immune system during pregnancy
Shift towards a TH2 type immune response by suppression of NF-Kappa B
43
how are embryos graded
- three numbers
- 1st number = number of cells
- 2nd number - degree of idealised blastomeres
- 3rd - degree of fragmentation
44
How is the blastocyst graded
1-4 for degree of expansion
5-6 degree of hatching
Blastocysts of grade 3 or higher further graded A-D for ICM and trophoectoderm
A - Tightly packed, many cells
B - Loosely packed, several
C - Very few cells
D – Degenerating cells
45
What is the implantation rate
- number of embryos implanted out of a number transferred over a period of time
46
Define failed implantation
- failure to reach a stage in which there is US evidence of intrauterine pregnancy
47
What are the criteria for recurrent implantation failure
- following the transfer of at least 4 embryos
- in at least 3 transfer cycles
- with good quality embryos
- in women ages <40 years
48
give some possible outcomes of IVF
```
Possible outcomes of IVF
• Ongoing clinical pregnancy
• Cycle cancellation
• Failed fertilisation
• Failed implantation
• Biochemical pregnancy
• Clinical miscarriage
• Ectopic pregnancy
```
49
list causes of recurrent implantation failure (broad)
- poor quality embryo
- lab factors
- endometrium
- uterine
- tubal
- endocrine
- immune
50
what are the causes of recurrent implantation failure due to poor quality embryos?
- sperm quality poor
- reduced ovarian reserve
- age
- diet and supplements - lack of vitamin D and folate
- DMI
- smoking (increases dose of FSH needed)
51
what are the causes of recurrent implantation failure due to lab factors
- handling of eggs
- cheap culture media
- exposure of embryos to light
- incubator conditions
- serum progesterone at HCG trigger
52
what are the causes of recurrent implantation failure due to poor endometrium
- infections
- poor development - lack of progesterone
- sub mucous fibroids
- congenital (uterine septa)
- adenomyosis -bleeding into wall of womb
- polyps
- uterine synechia/Ashermans syndrome (adhesions)
53
what are the causes of recurrent implantation failure due to tubal causes
- hydrosalpinges
54
what are the causes of recurrent implantation failure due to endocrine causes
- DM
- PCOS
- POI
- Thyroid disease
55
what are the causes of recurrent implantation failure due to immune causes
- antiphospholipid syndrome
56
what are the tests done following recurrent implantation failure
- FSH, AMH, astral follicle count
- testosterone, sex hormone binding globulin (PCOS)
- TSH and thyroid peroxidase antibody
- lupus anticoagulant test
- HbA1C
- pelvic US and transvaginal US
57
how can gamete quality be improved
- stop smoking
- supplements
- reduce alcohol
- weight control
- good diet
58
how can laboratory protocol be improved in RIF
- insemination by ICSI
- careful embryo selection, assisted hatching, blastocyst transfer
- gamete donation
59
how does APS cause recurrent implantation failure
- via defective placentation
- down regulates HCG, integrins and cadherins, reducing trophoblast proliferation and growth
- on decimal side APL is pro inflammatory - causing neutrophil infiltration, secretion of cytokines and complement activation
60
what are the causes of persistent endometrial fluid
```
• Ovarian stimulation (uterine or cervical)
• High dose Estrogen
• Low Estrogen
• Tubal-Hydrosalpinges
• Endometrial
– Polyp or fibroid
– Asherman’s synechia – Cervical stenosis
– Chronic infection
```
61
list some treatments for RIF
- endometrial scratch
- LMWH and aspirin
- hysterscopic resection of fibroids, polypectomy
- blastocyst transfer
- salpingectomy for hydrosalpinges
62
what does the trophoblast split into
syncytiotrophoblast (becomes continuous with wall of uterus) and cytotrophoblast
63
what does the embryo blast split into
hypoblast and epiblast - bilaminar disc
64
what is gastrulation
during week 3 bilaminar disc changes into three layers - forms endoderm, mesoderm and ectoderm
65
what makes up the innate immune system
- body barriers
- immediate actions (AMP's)
- PRR's
- leukocytes of innate immunity ( neutrophils, macrophages, NK cells and dendritic cells)
66
what do pattern recognition receptors recognise
Pathogen Associated Molecular Patterns (PAMPs) synthesised by microorganisms
and
Damage Associated Molecular Patterns (DAMPs) which are associated with components of host cells that are released during cell damage or death
67
what does activation of PRR's cause
- secretion of inflammatory cytokines, type 1 IFN, chemokine and antimicrobial peptides
- activation of macrophages, recruitment of neutrophils
- maturation of dendritic cells - adaptive immunity
68
where are TLR's located
on the cell surface
69
where are NLR's located
in the cytoplasm
70
what are the roles of the innate immune system in the female reproductive tract
- passage of spermatozoa
- facilitate implantation
- allows pregnancy to continue to term
- protect against infections
71
which cells are TLR's NOT expressed from in female reproductive tract
vaginal cells
72
which hormone dampens immune response and which increases it
- oestrogen dampens
| - progesterone increases it
73
what is the role of the immune system in menstruation
- after progesterone surge high immunity
- arrival of neutrophils and macrophages to uterine decidua
- production of enzymes to degrade connective tissue of endometrium MMP
- Clearance of tissue fragments
74
what happens to the immune response in the third trimester
- influx of immune cells to the myometrium
- promote contraction of the uterus
- expulsion of baby and rejection of placenta
75
which two cell types are needed for implantation
NK cells and dendritic cells
76
what is epigenetics
none genetic influences on gene expression
77
what is the difference between methylation and acetylation
methylation - works on DNA repressing gene expression
Acetylation - works on histones to increase transcripton
78
what is developmental plasticity
selecting the right phenotype to fit the anticipated future environment
79
what did the dutch famine birth cohort study find
that in utero exposure to famine effected offspring health - higher incidence of CHD, COPD, high BP
80
What is the barker early/foetal origin hypothesis
- low infancy weight increased death from IHD
81
What is the waddington epigenetic landscape
landscapes influenced by environment, which influences the base on which proteins are coded
we are like balls rolling down a hill
82
define infertility
- conception has not occurred after a year of regular unprotected intercourse (2-3 times a week)
83
what is the meaning of primary and secondary infertility
Primary
- woman has never conceived
Secondary
- she has previously concieved even if it has ended in miscarriage or termination
84
what are the conditions needed for a pregnancy to happen
- egg produced and ovulation
- adequate sperm release
- sperm must reach egg
- egg must implant
85
what preconception advice is offered to couples
- weight loss
- stop smoking
- cut down on alcohol
- folic acid
- smear
- intercourse 2-3x per week
86
put these stages of IVF in order:
- pregnancy test
- embryo culture
- insemination
- luteal support
- semen collection
- ovarian stimulation
- fertilisation check
- embryo transfer
1. ovarian stimulation
2. semen collection
3. insemination
4. fertilisation check
5. embryo culture
6. embryo transfer
7. luteal support
8. pregnancy test
87
describe the process of ovarian stimulation and collection of oocytes for IVF
- stimulate ovaries to produce multiple follies
- suppress normal cycle using GnRH agonist
- high dose FSH and LH to increase follicle number
- side effects include OHSS and increased risk of cancer
- monitor follicular development by transvaginal USS until 2+ follicles >17mm
- hCG given to mature
- oocytes aspirated by US guided catheter
88
describe the process of sperm collection and prep for IVF
- Collected through natural or electroejaculation
- sperm prepared - seminal plasma removed
- sperm selection based on viability or genetic characteristics
- SYBR14 - plasma membrane integrity testing - shows up green
- FITCPNA for the acrosome
- sex sorting can be done using flow cytometry as x and y sperm have different charges after fluorescence is applied
89
describe the process of maturation and embryo transfer for IVF
- cleavage 24 hours after fertilisation
- mature for 2-5 days
- transferred at 4-8 cell stage by abdominal USS guided catheter
- extra embryos cryopreserved
90
describe the process of luteal support in IVF
- in IVF multiple follicles = multiple corpus luteum = lots of progesterone - sharp decrease after luteal phase
- GnRH also causes a short luteal phase
- give women a oestrogen and progesterone supplement
- up to 12 weeks
91
what are the indications for using intracytoplasmic sperm injection (ICSI)
- low morphology and motility
- damaged acrosome
- immature sperm
92
what can pre-implantation genetic diagnosis screen for
- huntingtons
- CF
- Sickle cell
93
describe the procedure of PGD
- routine IVF
- zona drilling at 8 cell stage
- remove 1-2 cells - blastomeres
- cells screened
- healthy embryos transferred or frozen
94
describe the process of mitochondrial donation
- nucleus from patient transplanted into oocyte with healthy mitochondria
- followed by IVF/ICSI and ET
95
what is gene editing as a reproductive technique
- CRISPR-Cas9 technology used to identify remove and replace faulty genes
- Cas9 digestes DNA
- synthetic DNA chains replace to introduce a desired trait
96
what is meant by reproductive technologies
- intervention used to control population, emphasis on improving or limiting fertility to prevent inbreeding
97
what is the extinction vortex
- small population leads to inbreeding, disease, inbreeding depression, smaller population and extinction
98
what can slow or block the extinction vortex
- assisted reproduction
| - genetic biobank
99
what is embryo splitting
- AI followed by embryo flushing, split to produce more embryos and implanted into foster uterus
100
describe semen extraction as a breeding technology
- semen taken from desirable bulls
| - can be sex sorted - sperm put in flow cytometer - detects different charges
101
describe the process of AI
- sperm inserted into cervix or vagina
- or laparoscopically or with long catheter vaginally
- when female in oestrus (controlled using intravaginal progesterone sponges)
102
describe the cloning process
- cell line created from genetically important animal
- chromosomes and polar body removed from oocyte of genetically unimportant animal
- inject cell into enucleated oocyte
- embryo matured and placed into surrogate mother
103
give an example of animal contraception
- suppression of GnRH with vaccine
104
what is a stem cell
a primitive cell that is capable of :
- self-renewal
- making a range of cell types
- can convert to different cell types
105
what is the difference between developmental potential and regeneration potential
- developmental potential - make embryos and tissues
| - regeneration potential - repair tissues
106
give some sources of stem cells
embryonic
- hESC - human embryonic stem cells
- EpiSC - epiblast stem cells
- XEN - extra embryonic endoderm stem cells
- TS - trophoblast stem cells
- induced pluripotent cells
107
how do stem cells differentiate
- in vitro differentiation directed by exogenous signalling ligands e.g. FGF, BMP, TGF Beta, WNT
- in vivo - selective pressures at "decision points"
108
what is the purpose of induced pluripotent stem cells
- can capture specific genome from a population/disease - for a specific disease e.g Long QT syndrome gene KCNQ1
- drug testing on normal and effected phenotypes to see effects before given to human subjects
- stem cells can be used for regenerative medicine - for example in Parkinsons disease where there is a depletion of dopamine secreting neurones in the basal ganglia of the brain
109
how can embryo quality be assessed
- turnover of amino acids - high amino acid depletion early on shows that an embryo will not develop - should steadily increase
- levels of glycolysis - low glycolysis rate = viable as stressed embryos do more glycolysis
- oxygen consumption - should be low at start with a spike at blastocyst time
- embryoscope/time lapse microscopy to continuously image embryo
- embryo grading
- ratio of ICM to trophectoderm using imaging
110
what is the advantage of using time lapse microscopy to assess an embryo
- do not have to open the incubator, reducing perturbation of embryo environment
- shows morphology and fragmentation
- dynamic and developmental events can be looked at
111
what are the advantages of using analysis of metabolism to assess an embryo
- none invasive
- reproducible
- independent of other parameters
- no ethical question raised
- easy to use
112
how does change in embryo metabolism and activity change embryo quality in the short term
- epigenetic modifications
- altered intracellular signalling
- metabolic stress
- gene expression changes
- apoptosis
- cell proliferation disturbed
113
how does change in embryo metabolism and activity change embryo quality in the long term
- reduced implantation capacity
- unbalanced fetal/placental allocations
- altered maternal nutrient provision
- abnormal fetal growth rate
- altered setting of neuroendocrine axis
- abnormal birth weight and postnatal growth
- cardiovascular and metabolic syndromes
114
how can stress change embryo quality
- by inducing apoptosis and fragmentation -leading to abnormal compaction - leading to modified fetal placental ratio
OR
- modified metabolism
OR
- modified gene expression
- maternal embryo asynchrony
- abormal fetal growth
115
How are the two different systems to measure fertility
By cohort or by time period
116
what is completed fertility
average number of children born by a cohort of women over their fertile years
117
what is a parity progression ratio
- the proportion of women with at least n children who go on to have at least 1 more child (Parity + 1)
118
list the types of cohort fertility measurements
- completed fertility
| - parity progression ratio
119
list the types of time period fertility measurement
- crude birth rate
- age specific fertility rate
- total fertility rate
- general fertility rate
120
what is crude birth rate
- the ratio of live births in a time period to the average population in that period - expressed as births per 1000 population
121
what is the formula for age specific fertility rate
births to women aged x/women in aged group x)*1000
122
what is the total fertility rate
a period measure expressed as a cohort - number of children who would be born per woman if she lived to the end of her childbearing age and bore children at each age in accordance with prevailing age specific fertility rates
123
give the formula for General fertility rate
(Births/women ages 15-49)*1000
124
what is fecundity and fertility
fecundity - the physiological capability of a woman to produce a live birth
Fertility - the number of live births actually achieved
125
what is the definition of a live birth
- breathes
- other evidence of life such as beating heart, pulsation of the umbilical cord or definite movement of voluntary muscles
126
what is azoospermia
- no sperm in semen - either obstructive or none
127
what is teratospermia
poor sperm morphology
128
what is asthenospermia
poor sperm motility
129
how can sperm be retrieved in IVF
- natural/electro ejaculation
- PESA - percutaneous epididymal sperm aspiration
- TESE - testicular sperm extraction
130
what is the FSH threshold/window concept
- FSH levels need to reach a certain threshold to stimulate ovarian follicle growth
131
what is the disadvantage of using a GnRH agonist for suppression of the pituitary cycle
- more likely to cause OHSS
132
what are the advantages of using GnRH antagonists for pituitary cycle control
- better control
- lower risk
- shorter treatments
- more flexible
- reversible
133
what is the dose of GnRH agonist/antagonist given dependent on during IVF
- age
- weight
- ovarian reserve
- baseline tests
- antral follicle count
134
where are embryos implanted in IVF
- 2cm from fundus
135
what are the complication of IVF
- multiple pregnancy
- ectopic - heterotrophic
- miscarriage
- psychological disappointment
- infection
- OHSS
136
give examples of both long and short range signals that modulate the periconceptual environment
short
- local responses to gametes and embryo
- changes female reproductive tract environment
long
- nutrition
- hormonal status
- environmental status
137
why should we study the preconception environment
- promote embryo production
- improving implantation and maintenance of pregnancy
- improving offspring health and welfare
138
before the zona pellucida is exposed to the sperm what must happen
- hyaluronidase enzyme digests the cumulus cells surrounding the zona
- idea is that the earliest sperm to reach the egg is sacrificial and undergo premature release of this enzyme
- clears a path to the zona for later sperm
- evidence that progesterone found in cumulus cells may induce this release
139
what receptors do sperm bind to on the oolemma
- JUNO - via Izumo
140
what triggers the resumption of oocyte meiosis (detailed)
- binding of sperm to oolemma
- PLCζ is released from sperm
- this stimulates release of secondary messengers IP3 and DAG
- IP3 causes release of calcium from calcium stores
- DAG causes activation of protein kinase c (PKC) which causes phosphorylation of proteins needed for continued development of the conceptus
141
what would happen if the oocyte didnt dispatch one set of chromosomes to the second polar body
would end up with a triploid cell
142
what is decidualization driven by
progesterone
143
what is the migration efficiency
distance in mm travelled by sperm in 7 minutes
144
what can be measured to detect if compaction has taken place
- oxygen consumption of the embryo - higher after compaction due to increased energy needed for blastulation - starts glycolytic metabolism
145
what can be measured quantitatively to assess embryo viability
- glucose consumption
- pyruvate consumption
- amino acid depletion
- oxygen consumption
- lactate production
- aa production
- ammonium production
- enzymes
- human leukocyte antigen
146
what is the function of pinopodes
- reduce the endometrial fluid
| - bring blastocyst closer to endometrium
147
why are medias best to be well defined for experiments
- so you know what is in the media and what is affecting growth of a cell
148
what are the methods of testing pluripotency
- embryoid bodies
- spin EB
- spin EB + GF
- GF + monolayer
- teratoma
- cell surface markers (however can be in any cell and have multiple markers0
149
why is differentiation usually irreversible
- chromatin and methylation changes that prevent re-expression of genes
150
why are none integrating methods of inducing pluripotency considered better
- any method that results in genetic material being inserted into a cell runs the risk of causing insertional mutagenesis
151
describe the shape of the placenta in the human and why is it built this way
the placenta is discoid - it is built like this as the blastocyst attaches at one location relatively quickly after implantation (free living phase short)
it is part conceptus and part endometrial
152
Describe the shape of the placenta in a pig or horse and why is it built this way
the placenta is diffuse or spread across the surface of the endometrium. This is because the conceptus is free living for longer and is larger at the time of implantation - it implants at multiple points
153
what can ROS do
damage cell membranes
inhibit tyrosine phosphotases
reduced action of calcium channels
kill the cell
154
what can estradiol influence to aid embryo transport
- ciliary beat frequency
- muscle contraction
- fluid secretion
155
how does estradiol cause tubal muscle contract
- PGE2
- PGF2 alpha
- IP3
156
SYBR14 and propidium iodide stain plasma membrane what colour
SYBR14 - green
| propidium iodide - red
157
what two stains are used to assess plasma membrane integrity
SYBR14 and propidium iodide
158
how many conditions are screened for on PGD
- 256
159
why do gene editing?
- fix genetic flaws
- prevent spread of disease
- promote beneficial traits
160
what can be done if someone produces no sperm
- spermatogonial stem cells
- implanted into testes
- ejaculate someone else sperm
