FISH studies of chromosome abnormalities in germ cells and its relevance in reproductive counseling.

Chromosome abnormalities are one of the major causes of human infertility. In infertile males, abnormal karyotypes are more frequent than in the general population. Furthermore, meiotic disorders affecting the germ cell-line have been observed in men with normal somatic karyotypes consulting for infertility. In both cases, the production of unbalanced spermatozoa has been demonstrated. Basically addressed to establish reproductive risks, fluorescence in situ hybridization (FISH) on decondensed sperm heads has become the most frequently used method to evaluate the chromosomal constitution of spermatozoa in carriers of numerical sex chromosome abnormalities, carriers of structural chromosome reorganizations and infertile males with normal karyotype. The aim of this review is to present updated figures of the information obtained through sperm FISH studies with an emphasis on its clinical significance. Furthermore, the incorporation of novel FISH-based techniques (Multiplex-FISH; Multi-FISH) in male infertility studies is also discussed.

Synapsis and meiotic recombination analyses: MLH1 focus in the XY pair as an indicator.

BACKGROUND: Anomalies in meiotic prophase I have been related to partial or total meiotic arrest. These anomalies include an abnormal synaptic process, resulting in disorders in meiotic recombination. METHODS: In the present study, we analyse primary spermatocytes from 12 infertile men (four with non-obstructive azoospermia, six with oligoastenoteratozoospermia, one with astenoteratozoospermia and one normozoospermic) and five control fertile donors using immunocytological techniques for synaptonemal complex, meiotic recombination and centromeric proteins. RESULTS: Mean numbers of MLH1 foci per cell, frequencies of cells presenting an MLH1 focus in the XY pair and percentages of cells affected by abnormal synaptic patterns (gaps and splits) are reported for each of the infertile patients and control men. A positive correlation between the frequency of cells showing a recombination focus in the XY pair and the number of autosomal recombination foci per cell is found. CONCLUSIONS: Reduced recombination in the XY pair and an increased number of cells affected by gaps may explain some idiopathic male infertility cases. The results suggest that recombination in the XY pair could be an indicator for general recombination frequency and for a successful meiotic process.

Identification of meiotic anomalies with multiplex fluorescence in situ hybridization: Preliminary results.

OBJECTIVE: To characterize meiotic anomalies in infertile men by multiplex fluorescence in situ hybridization (M-FISH) and to determine whether synaptic problems affect specific bivalents or whether anomalies are random. DESIGN: Analysis of meiotic preparations with standard techniques and M-FISH. SETTING: Assisted reproduction centers and Universitat Autònoma de Barcelona. PATIENT(S): Three fertile men undergoing vasectomy, four sterile patients with oligoasthenoteratozoospermia, and one patient with a Robertsonian translocation t(13;14). INTERVENTION(S): Unilateral testicular biopsy in controls and patients with oligoasthenoteratozoospermia and collection of a semen sample from the translocation carrier. MAIN OUTCOME MEASURE(S): Identification of bivalents in metaphase I and chromosomes in metaphase II and characterization of chromosome abnormalities. RESULT(S): All bivalents in metaphase I and all chromosomes in metaphase II could be identified. In controls and in one patient with oligoasthenoteratozoospermia, meiosis was normal. Other patients with oligoasthenoteratozoospermia showed different types of anomaly: desynapsis, breaks, precocious XY separation, or cryptic reorganizations. The Robertsonian translocation t(13;14) was easily identified. CONCLUSION(S): Results confirm the high incidence of synaptic errors in oligoasthenoteratozoospermia patients. Bivalents in metaphase I and chromosomes in metaphase II were individually identifiable. Nondisjunctional errors or small reorganizations overlooked in classic meiotic preparations were identified. Synaptic anomalies seem to affect meiotic bivalents at random.

Outcome of intracytoplasmic sperm injection in relation to the meiotic pattern in patients with severe oligoasthenozoospermia.

OBJECTIVE: The aim of the study was to evaluate the intracytoplasmic sperm injection outcome in a selected group of patients with oligoasthenozoospermia in relation to the results obtained from their meiotic analysis. DESIGN: Retrospective clinical study. SETTING: An assisted reproduction service and a university department. PATIENT(S): One hundred thirty-seven men with oligoasthenozoospermia grouped in relation to their meiotic pattern. INTERVENTION(S): Two hundred twenty-four intracytoplasmic sperm injection cycles from 137 men with oligoasthenozoospermia in whom diagnostic meiotic analyses had been performed. MAIN OUTCOME MEASURE(S): Fertilization, pregnancy, implantation, and abortion rates. RESULT(S): There were no significant statistical differences in fertilization, pregnancy, implantation, or abortion rates among the three groups studied. CONCLUSION(S): No statistically significant differences in fertilization, pregnancy, implantation, or abortion rates were found in patients with oligoasthenozoospermia in relation to the meiotic pattern.

Spermatogenic patterns and early embryo development after intracytoplasmic sperm injection in severe oligoasthenozoospermia.

PURPOSE: Evaluate the influence of different baseline spermatogenic patterns [meiotic pattern (normal or abnormal), sperm concentration (> 1 x 10(6)/mL or < or = 1 x 10(6)/mL), and the combined meiosis-sperm concentration pattern] on early embryo development in severe oligoasthenozoospermia. METHODS: Embryo outcomes (fertilization rate, cleavage rate, and 4-cell stage embryo division rate on day 2) after IVF-ICSI in 75 oligoasthenozoospermia and 79 normozoospermic males. RESULTS: The embryo division rate was significantly lower in oligoasthenozoospermia compared to normozoospermia (50.43% vs. 58.72%, p < 0.01) and in the oligoasthenozoospermia group for meiotic anomalies (43.40%), sperm concentration < or = 1 x 10(6)/mL (44.35%), and the combined pattern < or = 1 x 10(6)/mL with meiotic anomalies (37.17%). Logistic regression analysis showed a synergic effect (OR = 2.00; 95% CI = 1.28-3.12) when the two spermatogenic patterns predictive of slow embryo development [meiotic anomalies (OR = 1.49; 95% CI = 1.03-2.15) and sperm concentration < or = 1 x 10(6)/mL (OR = 1.53; 95% CI = 1.09-2.13)] were present. CONCLUSIONS: The data suggest that the early embryonic developmental capacity is inversely related to the severity of spermatogenic impairment (meiotic anomalies and/or sperm concentration < or = 1 x 10(6)/mL).