practical 1: gametogenesis, ARTs + CVS development Flashcards
How do primordial germ cells arise and what do they do?
Arise from the epiblast layer of the bilaminar disc
Migrate in 4th week to genital ridge of the primitive gonads (arrive 5th week)
They are pluripotent
What is a trisomy?
It is a form of aneuploidy where an extra chromosome is present
What is a syndrome?
A group of symptoms/signs that occur together with a common cause
What is the incidence of Edward’s syndrome?
1/5000 live births
What is the prognosis of Edward’s syndrome?
85% lost by 10weeks gestation
most die at 2mths
5% live past 1yr
What are the clinical features of Edward’s?
low-set ears (malformed), microcephaly, CHDs, small mouth, deficient manible (micrognathia), learning dis, CLPs
What is the incidence of patau’s (T13)?
1/20,000 live births
What clinical features are present in patau’s?
learning dis, HPE, CHD, deafness, CLP, eye defects (e.g. micophthalmia), polydactyly
what is the prognosis of patau’s?
90 % die by 1mth (5% live beyond 1 yr)
What is kleinfelter syndrome? What is its most common cause?
XXY (extra X chromosome)
Caused by non-dysjunction of XX homologues in gametogenesis (most common) –> therefore maternal cause
Give an example of a structural chromosomal abnormality?
Prader-willi syndrome, fragile X syndrome, Angelman syndrome
What is the cause of prader-willi syndrome?
Microdeletion of paternal long arm chromosome 15
N.B. may need to spot on the karyotype
What is the incidence of prader-willi syndrome?
1/15000 live births
what is the incidence of kleinfelter’s syndrome?
1/500 live births
Define zygote?
a cell formed from fertilsation of an oocyte and sperm (has the diploid number of chromosomes)
Define morula
16 cell stage in development
Define blastocyst
when a blastocele forms w/in the morula forming an ICM and outer trophoblast
Where does fertilisation normally occur?
Ampulla of the uterine tube
When does implantation occur?
6-7 days AFTER fertilisation
Where does implantation normally occur?
anterior or posterior uterine wall
5 risk factors of ectopic pregnancy
Coil, c-section/uterine surgery, endometriosis, previous ectopic, smoking, PID, salpingotomy
Signs and symptoms of ectopic
asymptomatic
bleeding (vaginal), lower abdo pain (commonest), brown vaginal discharge, shoulder tip pain
if rupture –> haemodynamically unstable (hypotension, tachy, low BP, pallor, ^ CRT, signs of peritonitis)
Investigation/managment approach to ectopic?
Pregnancy test (urinary) –> pelvic USS if +ve –> if can’t find on US then pregnancy of unknown location –> serum beta hCG
medical: IM methotrexate, serum hCG monitored
surgical (^^^^ hCG): laparscopic salpingectomy (salpingotomy if problem w/ other tube)
Or conservative watchful waiting if very low hCG/stable
if haemodynamically unstable (resuscitate using ABCDE approach)
What is a lithopedian? how does it occur?
“stone baby” –> when a fetus is lost in pregnancy (early on) + calcifies
What is the incidence of endometriosis?
1/10 (reproductive age)
What happens in endometriosis?
Growth of endometrial tissue in sites outside of the uterus (oestrogen dependent)
What are some sites of endometriosis?
colon, lung, peritoneum, ovaries, urinary tract, umbilicus, cul-de-sac
What are the symptoms of endometriosis?
Symptoms occur during menstruation
can be asymptomatic
CYCLICAL PELVIC PAIN = common (dysmenorrhea)
subfertility
constant pain if adhesions formed
Other symptoms based on site of ectopic endometrial tissue: deep dyspareunia, dysuria, dyschezia (painful defacation)
Why does endometriosis cause/increase risk of subfertility?
Adhesions in the uterine tubes
what are some complications of endometriosis?
Ectopic pregnancy
subfertility
What is a hormonal cause of subfertility in women?
PCOS
give 9 different ARTs?
intrauterine insemination ICSI Intracytoplasmic morphologically selected sperm IVF In vitro maturation of oocytes GIFT: gamete intrafollopian transfer ZIFT: zygote intrafollopian transfer Uterine transplant mitochondrial transfer
If a man has obstructive reasons for infertility, what can be done?
Surgical retrieval of sperm PESA (percutaenous epidydimal sperm aspiration) or TESA (testicular sperm aspiration)
What is intrauterine insemination indicated for?
Anti-sperm antibodies
What is intracytoplasmic sperm injection (ICSI) indicated for?
Severe male infertility (i.e. morphology, motility and low sperm count problems)
What is in vitro maturation of oocytes? Who is it good for?
This is similar to IVF but avoids risk of OHSS (doesn’t use gonadotropins) –> oocytes are retrieved during cycles (disadv: retrieves less eggs than IVF)
so is therefore good for women at risk of OHSS (e.g. PCOS)
What is GIFT? What is GIFT good for?
Religious people as fertilisation occurs in the body
Gametes placed in catheter + injected into fallopian tube
When do the progenitor heart cells produce the primary heart field in the LPM?
Day 16-18
What do Primary heart field become?
atria, LV, most of RV
When does the 2HF form? what does it become?
Day 20-21
forms the rest of the RV + outflow tracks
When does the heart tube bend/loop?
day 23-28
when do the major septa of the heart develop?
Day 27-37
What separates the L + R atria?
septum primum and then septum secundum forms
What contributes to lengthening of the outflow tracts?
NCCs
What is the difference between acyanotic and cyanotic heart disease?
opposite type of shunting
What is the F. ovale function?
allows blunt to shunt from R–>L to bypass lungs in fetal circulation
if remains patent + large –> acyanotic heart disease
What are the two causes of dextrocardia? How can you differentiate them
1) abnormal gastrulation (very early on) –> situs invertus would be present
2) abnormal cardiac looping (situs invertus not present)
What are the problems of dextrocardia?
Pulmonary and cardiac disease ^ risk
Why are SSRIs linked to ^ risk of dextrocardia/laterality defects?
Disrupt 5-HT pathways –> 5HT important in establishing laterality (L/R axis) [left sidedness]
What do 20% of people w/ situs invertus have?
Kartanger’s syndrome (abnormal cilia) –> bronchiectasis, chronic sinusitis
what is the incidence of ASDs? Do they occur equally in males and females?
- 4/10,000 births
2: 1 F:M
What are the different types of ASD?
Patent F. ovale
ostium secundum defect –> either septum primum or secundum is affected
Cor triloculare biventriculare (complete absence)
What are the problems of ASDs?
pulm HTN –> RVH –> Eisenmenger syndrome
What are the two types of VSD? which is more common?
Menbranous and muscular. Muscular is more common but less serious
What is the incidence of VSD?
12/10000 births
what is the consequence of a large VSD?
Pulmonary HTN
What is Eisenmenger syndrome?
Reversal of the L–>R shunt to R–>L
How does common truncus arteriosus occur and what are the consequences for the fetus?
conotruncal divisions fail to form so no separation of the Ao and pulmonary trunk
consequences: mixing of oxyg./deox. blood –> cyonsosis
why might a fetus with outflow tract abnormalities have craniofacial malformations?
why might they not?
NCCs are involved with craniofacial development [FACIAL SKELETON] but also development of the heart (signalling of the 2HF). Therefroe problems w/ NCCs cause both cardiac and craniofacial abnormalities (e.g. treacher collins syndrome)
if the cause is due to the 2HF problems rather than NCC
How does transposition of the great vessels occur?
conotruncal septum fails to follow its normal spiral course + runs straight down
this means RV connects to Ao and LV connects to Pulmonary trunk
What are the 4 features of TOF?
VSD
RVH
Pulmonary stenosis
overriding aorta (Ao positioned directly over VSD)
What is the incidence of TOF?
9.6/10,000 births
What are the clinical consequences of TOF?
Mixing of blood (overriding Ao) lead to a cyanotic baby
What occurs to the internal thoracic arteries in coarctation of the aorta?
Dilation as blood takes different route to lower limbs (subclavian –> ITA –> …)
What monosomy is associated with Coarctation of the aorta?
Turner’s syndrome
what would post-ductal coarctation present?
even w/ the ductus arteriosus patent –> hypotension in the legs
post-ductal is more common and is associated with collateral circulation
When does gastrulation take place?
week 3 beginning (d 14)
What are the types of acyanotic CHD?
- Increased pulmonary blood flow (L–>R) –> VSD, ASD, PDA
2. Obstrcution to flow from ventricles –> e.g. pulmonary/Ao stenosis, coarctation Ao
What are the types of cyanotic CHD?
- Decreased pulmonary flow –> e.g. TOF, Tricuspid atresia, pulmonary atresia
- Mixed flow –> TOF, Common truncus arteriosus, HLHS, Transposition of the great vessels, total anomalous pulmonary venous return
What are the features of hypoplastic left heart syndrome?
Underdeveloped LV
Small Ao
ASD
PDA
What are some signs of kleinfelter’s syndrome?
Gynaecomastia
small testis
infertility
Low IQ
What chromosomal abnormality is seen in DiGeorge syndrome?
microdeletion 22q11
What are the different types of chromosomal abnormalities?
Numerical: trisomy, monosomy
Structural: fragile sites, deletions
What is Jacob’s syndrome?
XYY (triploidy - extra Y chromosome)
What is severe male infertility?
Abnormal morphology
abnormal motility
low sperm count
