L1 pt. 1: Transport and Quality Assessment Flashcards
What is the function of the uterotubal junction?
Valve that controls movement of spermatozoa between oviduct and uterus
How is sperm quality assessed in labs (4 example techniques)
- CASA: Morphology and motility (with reference to WHO quality parameters)
- Live/dead stain (routine in andrology labs)
- PICSI tests ability to bind hyaluronic acid and thus oocyte material
- Flow cytometry which automatically measures quality parameters; widely used in livestock andrology
Further stain example: JC-1 stain for mitochondrial membrane potential (specific for ATP production in midpiece of sperm)
What processes take place in the testes and can impact fertility if impaired? (x2)
Sperm assembly and DNA condensation
What sperm processes occur in the epididymis and can affect fertility if aberrant? (x3)
Sperm maturation, lipid and protein modification, sperm storage
Factors that affect male fertility in seminal plasma: (x2)
Accessory protein secretion, adsorbance to sperm surface (aggregation)
What unique motility is observed in certain marsupial species?
- Cooperative Swimming
- Sperm swim better in pairs, and motility is erratic in unpaired specimens
Types of DNA damage that can impact sperm quality (x4):
- Direct injury to purines/pyrimidines
- Single and ds breaks
- Cross-linking
- Chromosomal rearrangements
How can damage to mitochondria affect sperm quality? -> Alternatively, how may this impact potential offspring?
- Damage to mDNA results in decreased ATP production
- This results in impaired motility
- In eutherian mammals, upon fertilisation, the tail is tagged with ubiquitin for degradation; damage to mDNA will not be transmitted to offspring in event of successful fertilisation
How can damage to sperm membrane affect sperm quality?
- Lipid peroxidation of polyunsaturated fatty acids results in impaired motility
Name a technique for sorting sperm head quality?
- MACS (Magnetic activated cell sorting)
How often are male factors involved in infertility cases?
50%
How can oxidative stress damage sperm?
- ROS implicated in various sperm events (capacitation, acrosome reaction, binding and traversing ZP)
- Can case severe damage (poor motility, morphological abnormalities, DNA damage and ultimately cell death)
How does DNA fragmentation come about? What factor is crucial in fragmentation differences observed between species?
- Impacted by various lifestyle and environmental factors
- Rate of fragmentation increases upon incubation at 37 degrees
- Higher concentration of cysteine groups in Protamine-1b reduces percentage of DNA fragmentation (confers greater stability in the gene)
+ 3 mechanisms through which the female reproductive tract prevents polyspermy
- Selective prevention of passage of sperm depending on surface protein expression (e.g. calreticulin, ADAM1a, 2, 3)
- Hardening ZP (via oviductal proteins such as heparin-like GAGs) -> resistance to hydrolytic enzymes
- Deploying cortical granules filled with hydrolytic granules upon first fertilisation -> increases hardness of ZP
+ Give two types of interaction that modulate sperm chemotaxis (excluding immune reactions)
- Hormonal interactions: Progesterone modulates CatSper activity, allowing calcium influx, activating capacitation
- Chemokine-receptor interactions using factors released by oocyte/GC e.g. CXCR4 on sperm and SF1, which 70% of sperm do not express -> point of selectivity
+ How might direct cell-cell interactions facilitate sperm selection in the female RT?
- Immunological selection
- Immune targeting of specific paternal antigens, inducing post-mating inflammatory response -> neutrophil influx into uterine lumen
+ What roles do ROS have in male fertility? Give examples (hydrogen peroxide)
- Physiological role: e.g. hydrogen peroxide stimulates capacitation via tyrosine phosphorylation (and also stimulates hyperactivation)
- Aetiological role: e.g. DNA fragmentation, lipid peroxidation of polyunsaturated FAs -> as seen in exposure to exogenous hydrogen peroxide
+ List 3 key exogenous sources of ROS
- Pathological source (e.g. hyperglycaemia, varicocele)
- Occupational (industrial, heat)
- Iatrogenic (radiation therapy)
+ How can exposure of sperm mitochondria to excess ROS cause infertility?
- Damage to mDNA
- Decreased ATP production
- Impaired motility
- Compounded by effect of lipid peroxidation
+ List 2 key lifestyle effects heavily associated with increased DNA fragmentation
- Smoking
- Obesity
What is TESA
- Testicular sperm aspiration, allowing surgical collection of the sample
- If you have no, or extremely low numbers of, sperm in your semen which means you can’t have a standard fertility treatment, you may be able to have sperm collected surgically
Findings of experiment into migration efficiency of goat sperm in cervical mucus:
- High migration efficiency (i.e. vanguard) of sperm in vitro was able to predict migration efficiency in vivo (i.e. progression to oviduct)
- It was also able to predict high penetration rate in IVF
