Reproductive Biology Quiz

Spermatogenesis

• Spermatogenesis is the process of producing sperm cells in males.
• It begins at puberty due to rising gonadotropin and testosterone levels.
• The process occurs within the seminiferous tubules of the testes.
• The time from spermatogonium to spermatozoa production is 65-70 days.
• New cycles of spermatogenesis are initiated every 2-3 weeks.
• In adult humans, 30-200 million spermatozoa are produced per day.
• Spermatogenesis is maintained throughout adult life.

Sperm Structure

• Sperm cells are among the smallest cells in the body (~1/20 mm).
• A sperm cell has a simple structure: head and tail.
• The tail, a flagellum, propels the sperm using a whipping motion.
• A coiled mitochondrion in the tail provides energy for movement.
• The head contains the nucleus and an acrosome.
• The acrosome contains digestive enzymes that help the sperm penetrate the egg.

Process of Spermatogenesis

• Spermatogenesis begins with spermatogonia which multiply via mitosis.
• Primary spermatocytes are formed via mitosis from spermatogonia.
• Meiosis produces secondary spermatocytes from primary spermatocytes, leading to haploid spermatids.
• Spermiogenesis is the process of spermatids differentiating into mature spermatozoa.

Roles of Sertoli Cells

• Sertoli cells contain receptors for FSH and testosterone.
• They form the blood-testis barrier which protects the developing sperm.
• They provide nourishment to developing sperm cells.
• They produce androgen-binding protein.
• They produce estrogen that acts as a paracrine agent stimulating differentiation.
• They produce inhibin to limit FSH secretion from the anterior pituitary.
• Sertoli cells phagocytose defective sperm cells.
• They secrete Mullerian Inhibitory Factor (MIF) during embryonic life.
• Damage or destruction of Sertoli cells can halt spermatogenesis.

Roles of Leydig Cells

• Leydig cells are responsible for steroidogenesis and testosterone secretion.
• They have LH receptors but lack FSH receptors.
• They also have estrogen receptors.
• Sertoli cells stimulate Leydig cell growth via estrogen.

External Agents Affecting Spermatogenesis

• Rapidly dividing and undergoing meiosis, sperm cells are vulnerable to external agents.

• These agents can alter sperm division.

• Chemical carcinogens

• Chemotherapeutic agents

• Drugs

• Environmental toxins

• Irradiation

• Extreme temperatures

• Smoking

• Malnutrition and deficiencies

• Obesity

• Bicycling

• Varicocele

Genetic Factors Affecting Spermatogenesis

• Klinefelter syndrome (XXY): impaired seminiferous tubule development
• Kartagener syndrome: organs reversed in position, immotile sperm
• Cystic Fibrosis: can lead to obstructed vas deferens and issues with sperm

Hormonal Regulation in Males

• Gonadotropin-releasing hormone (GnRH) prompts the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH), triggered by low testosterone levels.
• Follicle-stimulating hormone (FSH) & luteinizing hormone (LH), released by the anterior pituitary, stimulate spermatogenesis and testosterone production.
• Testosterone plays a crucial role in the development of male sex organs and secondary sexual characteristics.
• Testosterone also provides feedback regulation by inhibiting LH secretion.

Semen Analysis (Seminal Fluid Analysis)

• Semen analysis evaluates fertility status by assessing semen quality via analysis.
• Also known as a sperm count test for male fertility.
• Key aspects: volume, liquefaction time, sperm count, morphology, motility, antibody agglutination, white blood cell count, PH, & Fructose levels.

Methods of Collection

• Clean specimen bottle used.
• Common methods: masturbation, coitus interruptus, collection condom, and condoms (after removing any lubricant/spermicides).

Methods of Analysis

• Makler counting chamber (evaluates sperm count & motility)
• Computer-assisted semen analysis (CASA)
• Hemocytometer

Sperm Penetration Assay (SPA)

• Eggs and ova from hamsters, without outermost layer, are exposed to prepared sperm to evaluate sperm penetration.
• Positive result indicates likely fertilization potential.

Advice Before Analysis

• Abstain from intercourse for 3 days before analysis.
• Avoid alcohol, smoking, and drug use (marijuana/cocaine).
• Sample collection close to body temperature or collected at the lab immediately prior to analysis is essential.
• Analysis should be conducted within 30 minutes to 1 hour after collection.

Computer-Assisted Semen Analysis (CASA)

• CASA uses automated or semi-automated analysis based on image analysis.
• It tracks sperm movement/motility using digitizing tablets.
• CASA quantitatively assesses sperm concentration, motility characteristics (like velocity), and more.
• There are many CASA systems.

Types of CASA systems

• Sperm Quality Analyzer (or Sperm lite)
• Integrated Semen Analyzer
• Sperm Class Analyzer
• Integrated Visual Optical System (iVOS) sperm

Drawbacks of CASA

• Accuracy depends on programmer skill and careful monitoring/routine updates.
• Small program changes can substantially alter results.
• Any abnormal results should be verified with an alternative (manual) method.

Post-Coital Test (PCT)

• Also called Huhner or Sims-Huhner test, it analyzes cervical mucus to understand its receptiveness to sperm.
• It's typically performed after intercourse and evaluates the interaction between cervical mucus and sperm at ovulation.

Normal Seminal Fluid Analysis Parameters

• Volume: 2-6 ml
• Liquefaction Time: 20-30 minutes
• Sperm Count: >20 million per ml
• Sperm Morphology: 30% normal head form
• Sperm Motility: 50% forward progressive motility
• Antibody Agglutination: <10%
• White Blood Cells: <1 million/ml
• pH: 7.2-8.0
• Fructose: Normal

Factors Affecting Results

• Collection Methods: Collection with condom (after cleaned) is better than masturbation; properly cleaned washed collection condoms are still considered better.
• Abstinence Period: Longer abstinence periods correlate with poorer results
• Frequent Ejaculation: Frequent ejaculation produces semen with more immotile sperm.

Abnormal Conditions

• Hyperspermia: Semen volume greater than 6ml
• Hypospermia: Semen volume less than 1.5 ml
• Aspermia: No semen produced
• Oligospermia: Sperm count less than 20 million/ml
• Asthenospermia: Motility less than 40%
• Teratospermia: Abnormal Morphology greater than 40%
• Necrospermia: Non-viable sperm
• Oligoasthenoteratospermia: A combination of the conditions above (4, 5, and 6).

Test your knowledge on sperm analysis, spermatogenesis, and related terms in reproductive biology. This quiz covers essential concepts such as sperm count, motility analysis, and the role of various cells in the male reproductive system. Challenge yourself and see how well you understand the intricacies of male fertility!