Week 10 - Andrology Notes
Why Andrology?
Most hospitals have fertility clinics, often within Gynaecology or Urology departments.
Andrology focuses on male fertility, providing essential information for the fertility process.
Andrology labs offer outpatient services, requiring skills in:
Patient bookings and referrals
Patient interviews
Results reporting
Coordination with external departments and GP practices
Sperm Production
Sperm production is hormonally regulated by the hypothalamus and anterior pituitary gland.
The hypothalamus releases gonadotropin-releasing hormone (GnRH).
GnRH stimulates the anterior pituitary gland to release:
Follicle-stimulating hormone (FSH)
Luteinizing hormone (LH)
FSH and LH act on the testes:
FSH encourages spermatogenesis within seminiferous tubules.
LH stimulates testosterone production in Leydig cells located between seminiferous tubules.
Development
The testicle contains approximately 700 feet of seminiferous tubules where sperm are produced.
Sperm are created from precursor germ cells, with a production rate of up to 120 million sperm per day.
Within the seminiferous tubules, germ cells are arranged in a specific sequence from the outside to the inside.
Stem cells lining the tubules initiate sperm production.
Diploid sperm cells divide into haploid spermatids.
Spermatogenesis takes about 64 days to complete.
Quality control checkpoints ensure the biological and genetic integrity of ejaculated sperm, despite the high production numbers.
Subfertility
Infertility is defined as the inability to conceive after 12 months or more of trying.
Approximately 1 in 7 couples in the UK (3.5 million people) experience difficulty conceiving each year.
Causes of infertility:
Unexplained: 25%
Ovulatory disorders: 25%
Tubal damage: 20%
Male factor infertility: 30%
Uterine or peritoneal disorders: 10%
Referrals to the andrology lab come from:
GPs for couples having unprotected sex for a year without conceiving.
Gynaecology and Urology departments.
Post-radiation and chemotherapy patients to assess fertility.
Morphology
The spermatozoon is a metabolically complex, motile, and genetically important cell.
It measures approximately 60 microns in length and consists of three sections:
Head
Neck
Tail
The sperm head contains:
A nucleus with highly compacted DNA.
An acrosome containing enzymes for egg penetration during fertilization.
The neck connects the head and tail, including the connecting piece and proximal centriole.
The tail comprises:
The axial filament.
The midpiece containing the axoneme, which functions as the engine.
The axoneme requires 200-300 proteins to function, with microtubules being the best understood.
Sperm microtubules are arranged in a "9+2" pattern: 9 outer doublets encircling 2 inner central doublets.
Defects in the sperm axoneme are associated with infertility.
Sperm Morphology Assessment
Morphology refers to the size and shape of sperm.
Sperm morphology is evaluated during semen analysis.
Males have varying percentages of abnormally shaped sperm. The World Health Organization (WHO) considers 4% or more normal sperm to be sufficient for fertility.
Abnormal sperm can reduce fertility, presenting with:
Misshapen heads (too large, too small, or extra heads).
Bent, coiled, stumpy tails, or tails incorrectly attached.
Factors increasing abnormal sperm percentage:
Increased testicular temperature.
Exposure to toxic chemicals.
Infection.
Genetic traits.
Examples of Sperm Morphology
Normal sperm:
Oval-shaped head.
Intact midpiece.
Uncoiled single tail.
Correct number of chromosomes.
Good motility in a straight line.
Macrocephaly (giant head):
Often carries extra chromosomes.
Caused by homozygous mutation of the aurora kinase C gene; genetic abnormality.
Tapered head sperm ("cigar-shaped"):
Often contain abnormal chromatin or DNA packaging.
Abnormal number of chromosomes (aneuploidy).
High temperature may exacerbate this condition.
Coiled-tail sperm:
Exposed to incorrect seminal fluid conditions or bacteria.
Damaged tails impair swimming ability.
Linked to heavy smoking.
Andrology Lab Procedures: Outpatient Clinic
Patients require a referral to be seen.
Toxicity-tested collection pots and instructions are provided to patients.
Patients book appointments via an online system.
Samples must be processed within one hour of production for accurate results.
Results are issued to GPs or referring clinicians.
Assessing and Preparing Semen Samples
Appearance and Consistency:
Normal semen: light grey, liquefies in 30 minutes, distinct odor.
Abnormal appearance: brown or red color, failure to liquefy after 60 minutes, mucus or jelly-like consistency, strong odor.
Sample described as normal or viscous.
Volume and pH:
pH measured using indicator papers; lower reference limit is 7.2.
Lower pH: blockage of seminal vesicles.
Higher pH: infection.
Volume measured by weight, assuming 1g = 1ml of semen.
The sample is weighed, accounting for the pot's weight.
Lower reference limit: 1.5 ml (1.4–1.7ml).
Determining Motility
Progressive sperm count is the most significant predictor of fertilization and pregnancy.
A minimum of 200 sperm on two slides are counted and categorized:
Progressive: sperm moving forward.
Non-progressive: sperm twitching or moving in small circles.
Immotile: sperm not moving.
Acceptable difference between counts on two slides accounted for.
Motility figures are reported.
Low motility:
Progressive motility under 32%.
Total progressive + non-progressive motility under 40%.
Low motility may require a repeat sample or referral to a fertility clinic.
Acceptable difference is defined by the Average (%) and Acceptable Difference table on page 11 of the transcript.
Determining Concentration
A 1:20 dilution is prepared using 950ul of diluent and 50ul of semen sample, placed into two tubes per patient.
A quick check determines the appropriate dilution based on sperm density on the slide.
The sample from one tube is placed in the bottom chamber and the other in the top chamber of the Haemocytometer.
Only whole sperm are counted; pinheads or debris are excluded; sperm heads crossing the right and bottom grid lines are ignored.
The Spermatozoa Dilution table is used to prepare the samples.
Determining Concentration (Continued)
Both sides of the counting chamber are counted, and the difference is checked against the reference graph.
The result is divided by the number of squares counted.
Fewer than 25 squares can be counted if there are more than 200 sperm in the first 5 or 10 squares.
The sperm concentration is given as millions per ml.
Low sperm count: classified as total sperm of 15 million per ml.
If no sperm are seen:
The sample is centrifuged, and one drop of the pellet is assessed for sperm.
If the concentration is low, the sample may be repeated, or the patient is referred to a fertility clinic.
Dilution Correction Factors table used, where the average count from the two sides of the haemocytometer is divided by the appropriate conversion factor.
Assisted Reproductive Technologies (ART)
Patients with abnormal motility, concentration, and/or morphology may undergo ART:
Intrauterine Insemination (IUI):
Ovulation is induced.
Semen is collected and prepared.
Prepared semen is inserted to increase sperm count at the fertilization site.
Success rate: 10-12% per round (same as a normal fertile couple).
In-Vitro Fertilization (IVF):
Superovulation is induced, and oocytes (eggs) are harvested.
Sperm is collected and prepared.
Several thousand spermatozoa are introduced to 1-2 oocytes in vitro (petri dish).
Fertilized oocytes are implanted into the uterus.
Success rate: approximately 25-50% per round.
Intra-Cytoplasmic Sperm Injection (ICSI):
Superovulation is induced, and oocytes are harvested.
Sperm is collected and prepared.
A single sperm is injected directly into the oocyte.
Success rate: approximately 25-50% per round (can be used with barely motile sperm).
Donor Sperm:
Used if the patient’s semen cannot be used in the above techniques.