Reproductive Biology Quiz

Fertility Analysis - Male Reproductive System

• The male reproductive system includes the following structures: urinary bladder, ureter, seminal vesicle, bulbourethral gland, prostate gland, ductus deferens, epididymis, testis, urethra, and glans of penis.
• Sperm is produced in the seminiferous tubules within the testes.
• The hypothalamic-pituitary-testicular axis regulates testosterone production, spermatogenesis, LH and FSH.
• GnRH (gonadotropin-releasing hormone) is synthesized by the hypothalamus and stimulates the anterior pituitary to release FSH and LH.
• FSH stimulates Sertoli cells which support spermatogenesis.

Fertility Analysis - Male Reproduction & Endocrinopathies

• Prolactin is a polypeptide hormone secreted from the anterior pituitary gland.
• Prolactin inhibits GnRH release, leading to decreased spermatogenesis and infertility in males, but this is considered pathologic.
• Normal prolactin levels in males are 2-18 ng/mL; 2-30 ng/mL in females; 10-210 ng/mL during pregnancy third trimester
• Inhibin B is a glycoprotein from the TGF-β family produced by Sertoli cells in response to FSH stimulation.
• Inhibin B controls FSH function via negative feedback and is a marker of Sertoli cell function.
• Inhibin suppresses GnRH-stimulated release of FSH.

Fertility Analysis - Male Infertility

• Varicocele: swelling of the testicular veins, contributing to 38% of male infertility cases. It results in decreased sperm count, motility, and abnormal morphology.
• Undescended testicle (Cryptorchidism): Inability of testicles to descend into the scrotum, occurring in 2-6% of newborns.
• Hormonal imbalance: Genetic conditions, gland malfunctions (hypothalamus, pituitary, thyroid, adrenal glands) and unhealthy weight can have impacts on sperm production and male fertility. Changes in LH, FSH, and testosterone levels can impact spermatogenesis.

Fertility Analysis - Evaluation of Male Infertility

• Important aspects of male infertility evaluation include: reproductive history, medical history, physical examination, semen analysis, endocrine evaluation, and advanced analysis.

Fertility Analysis - Semen Analysis

• Semen analysis is critical for assessing male fertility potential, providing a global measure of testicular/epididymal function, vasal patency and accessory sexual gland function.
• A normal semen volume is 2–6 mL after 2–7 days of abstinence.
• Color variations in semen can indicate potential issues.
• Greyish white color is considered normal, while red semen may point to prostate inflammation, and yellow/green to infections, jaundice, or vitamin/medication presence
• Aspermia: no ejaculate after orgasm; Hypospermia: under 0.5 mL of semen; Hyperspermia: over 6 mL of semen.

Fertility Analysis - Semen pH

• Normal semen pH is 7.2 - 8.2, increasing slightly after ejaculation.
• Variations in pH are typically due to prostate or seminal vesicle inflammation.
• A low semen volume and pH below 7.0 usually signals ejaculatory duct obstruction.

Fertility Analysis - Sperm Count & Morphology

• Sperm counts are reported as millions of sperm per milliliter (e.g., 15 million per mL). Total sperm count is the product of sperm concentration and semen volume.
• Conditions like normozoospermia (completely normal semen sample), oligozoospermia/oligospermia (<15 million/mL), and azoospermia (absence of sperm) are diagnosed based on total sperm count.
• Azoospermia can be obstructive or non-obstructive.
• Obstruction may be in the epididymis, vas deferens, or reproductive tract
• Non-obstruction suggests problems with sperm production or testicle structure/function.

Fertility Analysis - Sperm Motility

• Sperm motility is classified as rapid progressive, slow progressive, nonprogressive, and immotile.
• Rapid progressive motility (>25 μm/s at 37°C and >20 μm/s at 20°C) is essential for successful fertilization.
• For proper semen analysis at least 32% of sperm must be graded A and B (rapidly progressive motile spermatozoa).
• Reduced sperm motility may be a symptom of issues related to male accessory sex gland secretion or emptying.
• Asthenozoospermia describes the condition of reduced sperm motility due to various factors such as poor nutrition, varicocele, toxins, smoking, age, cancer treatments, and febrile episodes, among others.

Fertility Analysis - Sperm Viability & Necrosis

• Vitality is assessed through staining methods when sperm motility is less than 40%.
• Necrozoospermia refers to dead/necrotic sperm in a semen sample.
• Normal semen samples contain less than 30% necrotic sperm. Moderate necrozoospermia is 50-80% and Severe necrozoospermia is over 80%. Complete necrozoospermia involves almost all cells being dead/necrotic.

Fertility Analysis - Sperm Morphology

• Sperm morphology quantitatively evaluates normal and abnormal sperm forms in an ejaculate using WHO classification.
• Abnormalities are based on head, tail, and mid-piece characteristics from postcoital cervical mucus or zona pellucida surface.
• Teratozoospermia describes an increased percentage of abnormal sperm morphology in the semen exceeding 96%.

Fertility Analysis - Biochemical Markers (Semen)

• Fructose test assesses seminal vesicle function and is used to identify obstructive azoospermia in males with low ejaculate volume.
• Low levels of fructose (WHO defined lower limit 13 µmol per ejaculate) with low semen volume and low pH supports obstructive azoospermia diagnosis.
• Endtz test detects peroxidase within the neutrophils in a semen sample. This supports screening for granulocytes in unusual conditions.

Fertility Analysis - Biochemical Markers (Blood)

• Testosterone levels (300-1000 ng/dL) vary daily (best measured 8 AM-10 AM) and decline approximately 1% per year after age 35.
• Hypogonadism is defined as a serum testosterone level under 300 ng/dL, exhibiting various physical signs like increased body fat, reduced strength and muscle bulk, low bone mineral density, decreased energy/motivation and libido among other symptoms.
• Prolactin levels in males range from 2-18 ng/mL. Mild elevations don't typically cause infertility, while significant elevations can inhibit FSH & LH release from the pituitary gland, decreasing testosterone levels.

Fertility Analysis - Oxidative Stress & Antioxidant Capacity

• ROS (reactive oxygen species) refers to oxygen metabolism by-products.
• Free radicals, including superoxide and hydroxyl radicals, indicate potential oxidative stress due to unpaired electrons.
• Antioxidant capacity of seminal plasma includes enzymatic antioxidants and non-enzymatic antioxidants such as vitamin C, E and zinc, with non-enzymatic antioxidants contributing to about 65% of the total antioxidant capacity (TAC)

Fertility Analysis - Sperm DNA Damage

• Sperm DNA integrity is crucial for fertilization and transmitting genetic material.
• DNA Damage includes single or double stranded breaks, interstrand and intrastrand cross-linkage, DNA base modifications and protamine mispackaging. Often termed as DNA fragmentation
• Procedures like the Comet assay (a single-cell gel electrophoresis) can be used to measure DNA breaks in sperm.

Fertility Analysis - Oocyte & Sperm Assessment

• Oocyte maturation includes nuclear and cytoplasmic maturation.
• Mature eggs arrest in metaphase II until fertilization.
• Oocyte quality can be assessed through OCCC structure (measuring cumulus expansion for potential fertilization success), zona pellucida and polar body morphology.
• The hypo-osmotic swelling test (HOST) detects sperm viability issues, especially in samples with testicular or epididymal aspiration. PVP (Polyvinylpyrrolidone) is a common immobilization medium for ICSI, but may damage mitochondria

Fertility Analysis - Physical Exams

• Breast evaluation for symmetry, noting any evidence of galactorrhea (abnormal secretion from the breasts) which could point to pituitary lesions, in a fertility evaluation. Galactorrhea commonly involves bilateral multiple duct discharges in appearance.
• Hysterosalpingogram (HSG) checks fallopian tube patency and uterine cavity for normal function.
• Antral Follicle Count (AFC) evaluates the number or recruited follicles from both ovaries in the earlier phase of the cycle via ultrasound. It serves as a marker for ovarian reserve. Folliculometry tracks follicle growth and ovulation timing for 9-20 days into the cycle, to confirm that ovulation has occurred.
• Chlamydia antibody testing checks for previous infection as a cause of potential salpingitis (inflammation of the fallopian tubes.) This accounts for over 50% of tubal factor infertility.

Test your knowledge on the key functions and components of male reproductive biology. This quiz covers crucial topics such as the blood-epididymis barrier, seminal fluid components, and oxidative stress in sperm. Perfect for students and enthusiasts of reproductive science.