Molecular Human Reproduction, Vol. 6, No. 9, 795-799,
September 2000
© 2000 European Society of Human Reproduction and Embryology
Testis and spermatogenesis |
AZFa deletions in Sertoli cell-only syndrome: a retrospective study
Service de Cytogénétique-Immunocytologie-Biologie du Développement et de la Reproduction, CHU et CNRS UPRESA 6025, Faculté de Médecine et de Pharmacie, Place Saint-Jacques, 25030 Besancion cedex, France
Abstract
Lack of data on the genotype–phenotype relationship in cases of AZF microdeletions is due to the limited number of histological investigations in human male infertility cases. We investigated the possibility of retrospective detection of Yq11 microdeletions by using DNA extracted from diagnostic testicular biopsies. We used histological criteria to select two series of material: 22 biopsies with Sertoli cell-only syndrome and 14 biopsies with maturation arrest at the spermatocyte I stage. Two markers, DFFRY and DAZ, were tested by nested polymerase chain reaction (PCR) in the two series. In the Sertoli cell-only syndrome series, we found four deletions affecting the DFFRY gene (18.2%). In the second series, no deletions were detected. Two conclusions may be considered, although the number of specimens analysed is limited: (i) the frequency of deletions observed in Sertoli cell-only syndrome allows us to suggest that deletion in the AZFa region may be involved in this pathology; and (ii) retrospective studies may yield some additional elements in our search for eventual genotype–phenotype relationships.
AZF/DFFRY/male infertility/Sertoli cell-only syndrome/Y chromosome
Introduction
The azoospermia factor (AZF) region of the Y chromosome was so named because of cytogenetic deletions only observed in infertile men (Tiepolo and Zuffardi, 1976
). Over the last decade many studies have been carried out to investigate the role of this region in spermatogenesis. Molecular studies in infertile men have suggested the localization of genes controlling spermatogenesis in the Yq11 region (Ma et al., 1993; Reijo et al., 1995; Lahn and Page, 1997). For many of these genes, the function is unknown as is their degree of their involvement in spermatogenesis. According to current data, genes located in Yq11 may be divided into two groups: Y-specific multi-copy genes (CDY, DAZ, PRY, RBM, TSPY, TTY1, TTY2) and X–Y homologous genes (DBY, DFFRY, EIF1AY, SMCY, UTY) (Lahn and Page, 1997).
It has been postulated that Yq11 molecular deletions affecting different loci (AZFa, AZFb, AZFc) could be responsible for the disruption of spermatogenesis at different stages and that there might be a correlation between the site of deletion and the histological gonad phenotype (Vogt et al., 1996).
Until now, we have considered proximal Yq11 microdeletions (locus AZFa) to be associated with Sertoli cell-only syndrome (Vogt et al., 1992, 1996; Qureshi et al., 1996; Pryor et al., 1997; Brown et al., 1998; Grimaldi et al., 1998; Ferlin et al., 1999), despite some contradictory publications (Qureshi et al., 1996; Ferlin et al., 1999). The DFFRY gene is currently considered as a candidate gene for the AZFa phenotype. The DFFRY gene might be involved in maintaining male germ cell lineage, like its X-homologue (DFFRX), which is involved in oocyte development (Brown et al., 1998).
Deletions involving the AZFb locus appear to be associated with spermatogenic arrest at the spermatocyte in the majority of cases (Najmabadi et al., 1996; Stuppia et al., 1996, 1998; Vogt et al., 1996; Girardi et al., 1997; Brandell et al., 1998; Lee et al., 1998; Krausz et al., 1999; Kleiman et al., 1999) with several exeptions (Najmabadi et al., 1996; Lee et al., 1998; Ferlin et al., 1999). The RBM1 and RBM2 genes have been mapped inside the AZFb region (Ma et al., 1993; Vogt et al., 1996). The RBM1 gene copy which is missing in the Y chromosome of AZFb-deleted patients can be considered as a candidate gene for expression of AZFb phenotype (Chandley and Cooke, 1994; Vogt et al., 1996; Elliott et al., 1997).
The AZFc locus containing the DAZ gene cluster is the most frequently deleted region in men with non-obstructive infertility (Kostiner et al., 1998; Simoni et al., 1998). Histologically, these deletions are associated with various spermatogenetic alterations, e.g. Sertoli cell-only syndrome, maturation arrest and hypospermatogenesis (Reijo et al., 1995; Najmabadi et al., 1996; Qureshi et al., 1996; Vogt et al., 1996; Foresta et al., 1997; Girardi et al., 1997; Pryor et al., 1997; Simoni et al., 1997; Brandell et al., 1998; Grimaldi et al., 1998; Lee et al., 1998; Stuppia et al., 1998).
The question of genotype–phenotype relationships remains open, because of insufficient data on the histological state in testis of patients with AZF microdeletions. However, 20 years ago infertile men underwent histological examination almost systematically. Here, we present a study on the use of diagnostic testicular biopsies for retrospective detection of microdeletions in the AZF genes, DAZ and DFFRY.
Materials and methods
Materials selection
Our study was approved by the Hospital Ethical Committee. Diagnostic testicular biopsies were collected over the last 35 years. All biopsy samples were fixed in a Bouin mixture, embedded in paraffin, and 7 µm thick tissue sections were stocked on glass slides. Two histologically homogeneous series were selected: 14 specimens with maturation arrest at the spermatocyte I stage, and 22 specimens with Sertoli cell-only syndrome.
DNA extraction and polymerase chain reaction (PCR)
Tissue sections on slides were deparaffinized in three xylene baths, and rehydrated by washing in serial dilutions of ethanol (100, 95 and 70%). Then the slides were soaked in a 1% Lugol iodine solution for 5 min, washed in double-distilled water, bleached for ~3 s in a 2.5% sodium thiosulphate aqueous solution, and then thoroughly washed in double-distilled water (Tbakhi et al., 1998). The sections were completely scraped off the slides with care to avoid cross-contamination, and transferred to a 1.5 ml microcentrifuge tube. 100 µl of TE buffer (EDTA pH 8 5 mmol/l, Tris–HCl pH 8 10 mmol/l) was then added to the tube, and mixed by vortexing for 10 s. 500 µl of LSN solution [lithium acetate 0.3 mmol/l, EDTA pH 8 1 mmol/l, Tris–HCl pH 8 10 mmol/l, sodium dodecyl sulphate (SDS) 2%] was added to the tube. The incubation was carried out at 37°C for 2 h with agitation. Then DNA was purified by the phenol–chloroform method followed by ethanol precipitation and air drying. DNA was taken up in 80 µl of ultrapure water. For one PCR reaction, 15–20 µl of such purified DNA was used. At the first stage, we carried out the amplification of GAPDH to control for DNA extraction.
The first duplex PCR reaction was carried out in a final volume of 100 µl, a reaction mixture consisting of 1x PCR buffer, MgCl2 3 mmol/l, DyNAzyme II DNA polymerase 9 IU (Finnzymes Oy, Finland), dNTP 250 mmol/l, external primer pairs 250 µmol/l each, and 20 µl of target DNA. Thermocycling (TouchDown thermal cycling system; Hybaid, UK) consisted of 5 min at 94°C, 25 cycles of 94°C for 1 min, 57°C for 1.5 min, 72°C for 1 min and finally the reaction was heated at 72°C for 5 min. The external primers for DAZ and DFFRY genes are presented in Table I.
|
A 1 µl aliquot of the first PCR reaction was transferred into a microcentrifuge tube containing 20 µl of a mix consisting of 1x PCR buffer, MgCl2 2 mmol/l, DyNAzyme II DNA polymerase 1.5 IU (Finnzymes Oy), dNTP 250 mmol/l, and internal primer pairs 125 µmol/l each. The internal primers for DAZ and DFFRY genes are shown in Table I
. Thermocycling consisted of 5 min at 94°C for one cycle, 1 min at 94°C, 1.5 min at 60°C, and 1 min at 72°C for 25 cycles, with a final 5-min extention at 72°C. Reactions were analysed on a 3% agarose gel. Each PCR experiment contained two negative controls (female DNA, and DNA from a patient with a cytogenetically detectable Yq deletion), plus a positive control and a water control. In the absence of amplification for one or both markers, we repeated the first and second amplification. If the result remained negative, then the DNA extraction was repeated.
Southern blot analysis
After 35 cycles of first amplification, 20 µl of mix were separated by electrophoresis on 1% agarose gel. The samples in the gel were depurinated by treatment with HCl 0.25 mol/l, denatured with NaCl 1.5 mol/l, NaOH 0.5 mol/l and then neutralized with Tris–HCl 1 mol/l, NaCl 1.5 mol/l. The samples were transferred to Hybond-N+ nylon membrane (Amersham, Orsay, France) in 20x sodium chloride/sodium citrate (SSC) and then fixed 20 min in NaOH 0.4 mol/l. The probes used in our analysis were reverse internal primers for DAZ and DFFRY genes labelled with 
-[32P]-dCTP, by the Tailing DNA labelling kit (Amersham). Prehybridization was performed at 65°C for 30 min in a QuikHyb hybridization solution (Stratagene, Montigny le Bretonneux, France), followed by hybridization in the same solution for 3 h at 60°C in the presence of 100 µg/ml of salmon sperm DNA and a radiolabelled probe. The membrane was first washed twice with 2x SSC, 0.1% SDS for 15 min at room temperature and then with 0.2x SSC, 0.1% SDS for 15 min at 60°C. The membrane was exposed for autoradiography.
Results
We performed DNA extraction for 36 samples of testicular biopsies which were 1–30 years old. For 35 testicular biopsies, DNA extraction was successful; for only one biopsy with a histological picture of Sertoli cell-only syndrome, DNA amplification failed with DAZ/DFFRY markers as well as with the GAPDH marker. In the group of 14 biopsies with maturation arrest at the spermatocyte I stage, 13 biopsies were found to be positive for DAZ/DFFRY markers. In one case, DAZ amplification was negative, while DFFRY was positive, but Southern blotting with a DAZ oligoprobe showed the presence of a DAZ locus. In the Sertoli cell-only syndrome series (21 biopsies), DNA amplification for the DAZ gene marker was positive for all samples; however, for four samples (18.2%), the DFFRY gene marker (AZFa) was negative (Figure 1). These negative results were confirmed by the Southern blot technique (Figure 2). The histological characteristics of biopsies with DFFRY gene marker deletion are summarized in Table II; examples are shown in Figure 3.
|
|
|
|
Discussion
Testicular biopsy was widely used for diagnosis 20 years ago; however, over the last two decades, this technique has been replaced by other, less aggressive, techniques. The successful use of spermatozoa or spermatids recovered from the testis for IVF has generated renewed interest in testicular biopsies. Studies concerning potential links between Yq microdeletions and non-obstructive infertility are relatively recent: therefore, at the present time, the number of reported cases with histological data remains limited.
Our work may provide some helpful data concerning possible relationships between Yq molecular deficit and the histological conditions of gonads. Bouin fixation has not been favoured for successful DNA extraction. However, the use of old diagnostic material (Bouin-fixed and paraffin-embedded) for molecular biology techniques has been demonstrated in some recent studies (Longy et al., 1997; Tbakhi et al., 1998). We confirm that the use of an adapted protocol for nucleic acid isolation and nested amplification technique is feasible for detecting microdeletions in archived material. In 35 out of 36 cases, we were able to extract DNA from testicular biopsies that allowed PCR amplification. The choice of markers is particularly important in our approach, because of the lower quality of the extracted DNA. Nevertheless, our approach may be useful because like all retrospective studies, it enables us to define histological criteria and select a histologically homogeneous series.
We selected Sertoli cell-only and maturation arrest cases for two reasons: these two pathologies have clear histological characteristics and a high frequency of Yq microdeletions in Sertoli cell-only syndrome has been reported in prospective studies (Foresta et al., 1998; Ferlin et al., 1999).
In the two histological series, two genes (DFFRY and DAZ) located in AZFa and AZFc loci respectively, were tested. Until now, rare deletions in AZFa loci have been most frequently associated with Sertoli cell-only syndrome (Qureshi et al., 1996; Vogt et al., 1996; Pryor et al., 1997; Grimaldi et al., 1998; Ferlin et al., 1999). On the other hand, a prevalence of deletions affecting the DAZ gene cluster (AZFc) have been observed in patients with non-obstructive infertility (Simoni et al., 1998) and associated with variable histological phenotypes (Table III). A co-existence of deletions affecting AZFa and AZFc loci has also been shown in patients with idiopathic Sertoli cell-only syndrome (Ferlin et al., 1999).
|
All four samples with DFFRY microdeletions were in the Sertoli cell-only syndrome group. The high frequency (18.2%) of AZFa deletions observed in Sertoli cell-only syndrome allows us to suggest that the AZFa region may be involved in this pathology, although, at the present time, we cannot define the size of the four deletions detected in the Sertoli cell-only series. The absence of amplification of the DFFRY marker in association with the positive DAZ marker seems to favour the presence of interstitial microdeletions in the AZFa or AZFa/b loci, rather than major terminal deletions involving the entire AZF region or double interstitial microdeletions in the AZFa/c loci.
Beyond all selection considerations, the fact that deletions were not found in the series of 14 biopsies with maturation arrest in meiosis I, may suggest that we must look for other causes of these situations: deletion of RBM copies in AZFb region (Vogt et al., 1996) or Y chromosome gene mutations (Sun et al., 1999). Some other genetic origin may be considered, as in the case of mice where maturation arrest is conditioned by several autosomal genes (A-myb, Atm, Hsp70.2, Mlh1) (Grootegoed et al., 1998; Kim et al., 1998).
In conclusion, our results show that Yq microdeletion detection is possible in fixed, paraffin-embedded, archived testicular material. This approach may be used to answer some current questions concerning the consequence of Y chromosome molecular pathology at the gonadal level. Moreover, the results of this study suggest the involvement of DFFRY (AZFa) deletions in Sertoli cell-only pathogenesis. In some cases of Sertoli cell-only syndrome, ultrastructural analyses have allowed information to be obtained on possible aetiological factors (Nistal et al., 1990; Terada and Hatakeyama 1991). Ultrastructural analysis was not applicable to our study material. However the application of ultrastructural, histochemical and immunohistochemical methods may be useful in understanding the repercussions of AZF microdeletions on the morphological aspects of testes.
Notes
1 To whom correspondence should be addressed at: Service de Cytogénétique-Immunocytologie-Biologie du Développement et de la Reproduction, CHU et CNRS UPRESA 6025, Faculté de Médecine et de Pharmacie. Place Saint-Jacques, 25030 Besancion cedex, France. E-mail: oxana_blagoskl{at}hotmail.com 
References
Brandell, R.A., Mielnik, A., Liotta, D. et al. (1998) AZFb deletions predict the absence of spermatozoa with testicular sperm extraction: preliminary report of a prognostic genetic test. Hum. Reprod., 13, 2812–2815.
Brown, G.M., Furlong, R.A., Sargent, C.A. et al. (1998) Characterisation of the coding sequence and fine mapping of the human DFRRY gene and comparative expression analysis and mapping to the Sxrb interval of the mouse Y chromosome of the Dffry gene. Hum. Mol. Genet., 7, 97–107.
Chandley, A.C. and Cooke, H. (1994) Human male fertility – Y-linked genes and spermatogenesis. Hum. Mol. Genet., 3, 1449–1452.[Abstract]
Chang, P.L., Sauer, M.V., Brown, S. (1999) Y chromosome microdeletions in a father and his four infertile sons. Hum. Reprod., 14, 2689–2694.
De Rosa, M., De Brasi, D., Zarrilli, S. et al. (1997) Short stature and azoospermia in a patient with Y chromosome long arm deletion. J. Endocrinol. Invest., 20, 623–628.[ISI][Medline]
Elliott, D.J., Millar, M.R., Oghene, K. et al. (1997) Expression of RBM in the nuclei of human germ cells is dependent on a critical region of the Y chromosome long arm. Proc. Natl Acad. Sci. USA, 94, 3848–3853.
Ferlin, A., Moro, E., Garolla, A. et al. (1999) Human male infertility and Y chromosome deletions: role of the AZF-candidate genes DAZ, RBM and DFFRY. Hum. Reprod., 14, 1710–1716.
Foresta, C., Ferlin, A., Garolla, A. et al. (1997) Y-chromosome deletions in idiopathic severe testiculopathies. J. Clin. Endocrinol. Metab., 82, 1075–1080.
Foresta, C., Ferlin, A., Garolla, A. et al. (1998) High frequency of well-defined Y-chromosome deletions in idiopathic Sertoli cell-only syndrome. Hum. Reprod., 13, 302–307.
Girardi, S.K., Mielnik, A. and Schlegel, P.N. (1997) Submicroscopic deletions in the Y chromosome of infertile men. Hum. Reprod., 12, 1635–1641.
Grimaldi, P., Scarponi, C., Rossi, P. et al. (1998) Analysis of Yq microdeletions in infertile males by PCR and DNA hybridization techniques. Mol. Hum. Reprod., 4, 1116–1121.
Grootegoed, J.A., Baarends, W.M., Roest, H.P. et al. (1998) Knockout mouse model and gametogenic failure. Mol. Cell. Endocrinol., 145, 161–166.[ISI][Medline]
Kim, E.D., Bischoff, F.Z., Lipshultz, L.I. et al. (1998) Genetic concerns for the subfertile male in the era of ICSI. Prenat. Diagn., 18, 1349–1365.[ISI][Medline]
Kleiman, S.E., Yogev, L., Gamzu, R. et al. (1999) Genetic evaluation of infertile men. Hum. Reprod., 14, 33–38.
Kostiner, D.R., Turek, P.J., Reijo, R.A. (1998) Male infertility: analysis of the markers and genes on the human Y chromosome. Hum. Reprod., 13, 3032–3038.
Krausz, C., Quintana-Murci, L., Barbaux, S. et al. (1999) A high frequency of Y chromosome deletions in males with nonidiopathic infertility. J. Clin. Endocrinol. Metab., 84, 3606–3611.
Lahn, B.T. and Page, D.C. (1997) Functional coherence of the human Y chromosome. Science, 278, 675–680.
Lee, J.H., Lee, D.R., Yoon, S.J. et al. (1998) Expression of DAZ (deleted in azoospermia), DAZL1 (DAZ-like) and protamine-2 in testis and its application for diagnosis of spermatogenesis in non-obstructive azoospermia. Mol. Hum. Reprod., 4, 827–834.
Longy, M., Duboue, B., Soubeyran, P. et al. (1997) Method for the purification of tissue DNA suitable for PCR after fixation with Bouin's fluid. Uses and limitations in microsatellite typing. Diagn. Mol. Pathol., 6,167–173.[ISI][Medline]
Ma, K., Inglis, J.D., Sharkey, A. et al. (1993) A Y-chromosome gene family with RNA-binding protein homology – candidates for the azoospermia factor AZF controlling human spermatogenesis. Cell, 75, 1287–1295.[ISI][Medline]
Najmabadi, H., Huang, V., Yen, P. et al. (1996) Substantial prevalence of microdeletions of the Y-chromosome in infertile men with idiopathic azoospermia and oligozoospermia detected using a sequence-tagged site-based mapping strategy. J. Clin. Endocrinol. Metab., 81, 1347–1352.[Abstract]
Nistal, M., Jimenez, F. and Paniagua, R. (1990) Sertoli cell types in the Sertoli-cell-only syndrome: relationships between Sertoli cell morphology and aetiology. Histopathology, 16, 173–80.[ISI][Medline]
Pryor, J.L., Kent-First, M., Muallem, A. et al. (1997) Microdeletions in the Y chromosome of infertile men. N. Engl J. Med., 336, 534–539.
Qureshi, S.J., Ross, A.R., Ma, K. et al. (1996) Polymerase chain reaction screening for Y chromosome microdeletions: a first step towards the diagnosis of genetically-determined spermatogenic failure in men. Mol. Hum. Reprod., 2, 775–779.
Reijo, R., Lee, T.Y., Salo, P. et al. (1995) Diverse spermatogenic defects in humans caused by Y chromosome deletions encompassing a novel RNA-binding protein gene. Nat. Genet., 10, 383–393.[ISI][Medline]
Reijo, R., Alagappan, R.K., Patrizio, P. et al. (1996) Severe oligozoospermia resulting from deletions of azoospermia factor gene on Y chromosome. Lancet, 347, 1290–1293.[ISI][Medline]
Simoni, M., Gromoll, J., Dworniczak, B. et al. (1997) Screening for deletions of the Y chromosome involving the DAZ (Deleted in AZoospermia) gene in azoospermia and severe oligozoospermia. Fertil. Steril., 67, 542–547.[ISI][Medline]
Simoni, M., Kamischke, A. and Nieschlag, E. (1998) Current status of the molecular diagnosis of Y-chromosomal microdeletions in the work-up of male infertility. Initiative for international quality control. Hum. Reprod., 13, 1764–1768.
Stuppia, L., Gatta, V., Calabrese, G. et al. (1998) A quarter of men with idiopathic oligo-azoospermia display chromosomal abnormalities and microdeletions of different types in interval 6 of Yq11. Hum. Genet., 102, 566–570.[ISI][Medline]
Stuppia, L., Mastroprimiano, G., Calabrese, G. et al. (1996) Microdeletions in interval 6 of the Y chromosome detected by STS–PCR in 6 of 33 patients with idiopathic oligo- or azoospermia. Cytogenet. Cell. Genet., 72, 155–158.[ISI][Medline]
Sun, C., Skaletsky, H., Birren, B. et al. (1999) An azoospermic man with a de novo point mutation in the Y-chromosomal gene USP9Y. Nat. Genet., 23, 429–432.[ISI][Medline]
Tbakhi, A., Totos, G., Hauser-Kronberger, C. et al. (1998) Fixation conditions for DNA and RNA in situ hybridization: a reassessment of molecular morphology dogma. Am. J. Pathol., 152, 35–41.[Abstract]
Terada, T. and Hatakeyama, S. (1991) Morphological evidence for two types of idiopathic `Sertoli-cell-only' syndrome. Int. J. Androl., 14, 117–126.[ISI][Medline]
Tiepolo, L. and Zuffardi, O. (1976) Localization of factors controlling spermatogenesis in the nonfluorescent portion of the human Y chromosome long arm. Hum. Genet., 34, 119–124.[ISI][Medline]
Vogt, P., Chandley, A.C., Hargreave, T.B. et al. (1992) Microdeletions in interval 6 of the Y chromosome of males with idiopathic sterility point to disruption of AZF, a human spermatogenesis gene. Hum. Genet., 89, 491–496.[ISI][Medline]
Vogt, P.H., Edelmann, A., Kirsch, S. et al. (1996) Human Y chromosome azoospermia factors (AZF) mapped to different subregions in Yq11. Hum. Mol. Genet., 5, 933–943.
Submitted on March 27, 2000; accepted on June 23, 2000.
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  A. Ferlin, B. Arredi, E. Speltra, C. Cazzadore, R. Selice, A. Garolla, A. Lenzi, and C. Foresta Molecular and Clinical Characterization of Y Chromosome Microdeletions in Infertile Men: A 10-Year Experience in Italy J. Clin. Endocrinol. Metab., March 1, 2007; 92(3): 762 - 770. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 G. H. Perry, R. Y. Tito, and B. C. Verrelli The Evolutionary History of Human and Chimpanzee Y-Chromosome Gene Loss Mol. Biol. Evol., March 1, 2007; 24(3): 853 - 859. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. H. Vogt AZF deletions and Y chromosomal haplogroups: history and update based on sequence Hum. Reprod. Update, July 1, 2005; 11(4): 319 - 336. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C.M. Luetjens, J. Gromoll, M. Engelhardt, S. von Eckardstein, M. Bergmann, E. Nieschlag, and M. Simoni Manifestation of Y-chromosomal deletions in the human testis: a morphometrical and immunohistochemical evaluation Hum. Reprod., September 1, 2002; 17(9): 2258 - 2266. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
O. Blagosklonova, C. Joanne, C. Roux, H. Bittard, F. Fellmann, and J.L. Bresson Absence of anti-Mullerian hormone (AMH) and M2A immunoreactivities in Sertoli cell-only syndrome and maturation arrest with and without AZF microdeletions Hum. Reprod., August 1, 2002; 17(8): 2062 - 2065. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. Kamp, K. Huellen, S. Fernandes, M. Sousa, P.N. Schlegel, A. Mielnik, S. Kleiman, H. Yavetz, W. Krause, W. Kupker, et al. High deletion frequency of the complete AZFa sequence in men with Sertoli-cell-only syndrome Mol. Hum. Reprod., October 1, 2001; 7(10): 987 - 994. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. Van Landuyt, W. Lissens, K. Stouffs, H. Tournaye, A. Van Steirteghem, I. Liebaers, O. Blagosklonova, and J-L. Bresson The role of USP9Y and DBY in infertile patients with severely impaired spermatogenesis Mol. Hum. Reprod., July 1, 2001; 7(7): 691 - 693. [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||