SN4
SHORT NOTE
5M
★ High-yield
Describe semen analysis with its normal values. Add a note on the composition of semen.
Normal Values (WHO 2021)
Semen analysis = the first and most important investigation of male infertility. The sample is collected after 2–7 days of abstinence and examined within 1 hour.
| Parameter | Reference value |
|---|---|
| Volume | 1.4–6 mL |
| PH | 7.2–8.0 (alkaline) |
| Sperm concentration | ≥ 16 million/mL |
| Total sperm count | ≥ 39 million per ejaculate |
| Total motility | ≥ 42% |
| Progressive motility | ≥ 30% |
| Normal morphology | ≥ 4% |
| Vitality | ≥ 54% live |
| Leucocytes | < 1 million/mL |
| Liquefaction time | Within 30–60 minutes |
Composition of Semen
| Source | Share | Contributes |
|---|---|---|
| Seminal vesicle | 60% | Fructose (energy for sperm), prostaglandins, fibrinogen; alkaline |
| Prostate | 30% | Citrate, acid phosphatase, zinc, fibrinolysin (liquefaction), PSA |
| Testis and epididymis | 5–10% | Spermatozoa |
| Bulbourethral gland | Small | Mucus for lubrication |
- Fructose is absent when the seminal vesicles or vasa are absent or obstructed — a useful discriminating test
- The alkalinity neutralises the acidity of the vagina (pH 3.5–4), which would otherwise immobilise sperm
Terminology
| Term | Meaning |
|---|---|
| Azoospermia | No sperm in the ejaculate |
| Oligozoospermia | Concentration below normal |
| Asthenozoospermia | Reduced motility |
| Teratozoospermia | Abnormal morphology |
| Aspermia | No ejaculate at all |
| Necrozoospermia | All sperm dead |
Applied Aspects
- At least two samples, 2–4 weeks apart, are needed — counts vary widely from day to day
- Azoospermia — distinguish obstructive (normal FSH and testicular volume) from non-obstructive (raised FSH, small testes)
- ICSI allows fertilisation with a single sperm, transforming the outlook in severe male factor infertility
- Post-vasectomy semen analysis at 3 months confirms sterility — the procedure is not immediately effective
All questions in Reproductive System
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- SN1Describe the mechanism of ovulation and enumerate its indicators. ★
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