الفهرس 
SPERMATOGENESISOnly 14 pages are availabe for public view
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Abstract
he classic definition of infertility is the absence of conception after 12 months of regular, unprotected intercourse (Evenson et al., 2002).
The (WHO) definition of infertility is the absence of conception after 24 months of unprotected intercourse (Evenson et al., 2002).
Pregnancy rates by intercourse in normal couples are approximately 20–25% per month, 75 % by six months, and 90% by one year (Lipshultz et al., 2009).
Etiology of 20% of cases of infertility is attributed to purely male factor etiology, while an additional 30% to 40% involve both male and female factor pathology (Donohue et al., 1990).
The goal of the infertility evaluation is to cause a successful pregnancy in the safest, most natural, expeditious, and cost-effective manner possible (Sabanegh and Agarwal, 2012).
Spermatogenesis is a specialized process of DNA reduction and germ cell metamorphosis, by which male primordial germ cells called spermatogonia undergo meiosis and produce a number of cells termed spermatozoa (Smith, 2009).
Spermatozoa are the mature male. Thus, spermatogenesis is the male version of gametogenesis. In mammals it occurs in the male testes and epididymis in a stepwise fashion, and for humans takes approximately 64 days (Smith, 2009).
In most instances, successful treatment of infertility requires that the urologist work closely with a gynecologist and occasionally an endocrinologist. The proper treatment of infertile couples often involves counseling and psychological support in addition to surgical or medical therapy (McCallum et al., 2001).
Semen analysis:
Is the single most important component of the laboratory evaluation of the infertile male patient. The semen should be collected 48 to 72 hours of abstinence from ejaculation (Wang et al., 2002).
Chromosomal abnormalities are found in approximately 10% of azoospermic men, 5% of severely oligospermic men, and 1% of normospermic men (Ronald et al., 2004).
Y-Chromosomal microdeletion assay:
Approximately 7% of azoospermic and severely oligospermic infertile men harbor a Y chromosome microdeletion that cannot be detected with a standard karyotype but can be identified using more sophisticatedgenetic techniques (Tyler-Smith & Krausz, 2009).
Medical Treatment for Male Infertility
With a few specific and important exceptions, male infertility generally is not amenable to medical treatment. Careful evaluation can identify those men with treatable conditions who may benefit from medical therapy (Thomas et al., 2010).
Most affected men have a congenital isolated gonadotropin deficiency associated with abnormal puberty, due to absent or abnormal pulsatile hypothalamic GnRH secretion. The endocrinopathy may be genetic in origin, resulting from failure of GnRH neuronal migration during embryogenesis (Kallman syndrome) or idiopathic (Thomas et al., 2010).
Varicocele Repair: The prevalence of varicoceles is approximately 10-15% in the normal male population and about 25-40% in infertile men. The weight of available evidence indicates that varicoceles have an adverse effect on spermatogenesis. The pathophysiology involved is unclear but widely believed to involve venous reflux and increased testicular temperatures because spermatogenesis is exquisitely temperature sensitive (Luna et al., 2007).
Vasovasostomy and Vasoepididymostomy About one-half million American men undergo vasectomy every year and approximately 2-6% of vasectomized men later seek reversal of their sterilization procedure. Obstructive azoospermia also may result from iatrogenic injuries to the vas deferens, usually during hernia repair (Eskandar et al., 2008).
Transurethral Resection of the Ejaculatory Ducts obstruction is a cause of infertility in 1-5% of infertile men, and should be suspected in men with normal, palpable vasa deferentia and semen analyses revealing low ejaculate volumes combined with low or normal sperm concentration and low or absent motility (Purcell et al., 2007).
Testicular Sperm Extraction and Aspiration In men with non-obstructive azoospermia and those in whom epididymal sperm aspiration techniques fail or are inapplicable, sperm may be retrieved directly from the testis. Open microsurgical testicular sperm extraction yields the greatest number of sperm with potential for cryopreservation (Keltz et al., 2006).
Epididymal Sperm Aspiration Sperm may be obtained by microsurgical epididymal sperm (MESA) aspiration at the time of vasoepididymostomy or as an isolated procedure in men with CBAVD or uncorrectable obstructions. The technique involves incision of an isolated dilated tubule, gradually moving more proximally, if necessary, until sperm are obtained (Baart et al., 2006).
Percutaneous epididymal sperm aspiration (PESA) using a fine needle has also been used successfully to obtain sperm and achieve pregnancy, but the technique is less reliable, the small quantities of sperm obtained are sometimes inadequate to allow cryopreservation, and pregnancy rates achieved have generally been lower than with the open technique (Keltz et al., 2006).
Male infertility represents one of the clearest examples of a complex disease , its impact on the psychological and social wellbeing of not only the index patient but also his or her partner makes it a major concern for health professionals, the identification of genetic factors is important for appropriate management of the infertile couple. However, a large proportion of infertile males are diagnosed as idiopathic, reflecting poor understanding of the basic mechanisms regulating spermatogenesis and sperm function. Furthermore, the molecular mechanisms underlying spermatogenic damage in cases of genetic infertility (for example Yq microdeletions) are not known. These problems can be addressed only by large scale association studies and testicular or spermatozoal expression studies in well-defined alterations of spermatogenesis. It is conceivable that these studies will have important diagnostic and therapeutic implications in the future.