Comparison of sperm retrieval rate between superficial and deep dissection during microscopic testicular sperm extraction.

Objective: The purpose of the study was to compare the outcome of microscopic testicular sperm extraction (micro-TESE) between superficial and deep dissection on the same testicle in terms of sperm retrieval rate (SRR). Patients and Methods: In a retrospective study from June 2019 to October 2021, 44 patients with nonobstructive azoospermia who underwent micro-TESE with positive results (mature sperm identified) were included. Eight patients were excluded from the study due to deficient documentation on superficial and deep dissection. A total of 36 patients were included; 60 testicles were examined for superficial and deep biopsies. Testicular histopathology was performed in all patients, and a hormonal evaluation was obtained before the micro-TESE attempt. Results: Thirty-six patients and 60 testicles were included in the study. Of them, 47 (78.3%) testicles had positive results. Superficial TESE was positive in 38 (63.3%) testicles, and deep TESE was successful in 45 (75.0%) testicles. An improvement of 13.9% in the SRR was observed, following deep dissection. However, there was no statistically significant difference (P = 0.166). Rates of positive sperm retrieval (from any side) did not differ significantly based on patients' age, microdissection testicular sperm extraction sides, and hormonal concentrations; these differences were not apparent after superficial or deep TESE. Conclusion: The presented findings suggest that although successful SRRs of deep TESE were higher than that of its superficial counterpart, there was no significant statistical difference. A larger body of evidence is needed to provide a higher grade of recommendation.

A study of the histopathology of collagen fleece (TachoSil) patching of tunica albuginea in the rat penis and a literature review of penile graft materials in experimental animals.

Background: A penile tunica defect may arise during surgery in patients with Peyronie's disease. Collagen fleece (TachoSil) has recently gained popularity in penile surgery to cover the tunica albuginea (TA) defect associated with clinical success. However, it is not known what the histological outcomes of these grafts are in the penis. We aimed to study the histopathology of the TachoSil graft in an experimental animal model for the regeneration of TA, inflammation, fibrosis, and the underlying cavernous tissue. Methods: Six adult male Sprague Dawley rats were used. The penis was degloved through a circumferential subcoronal incision. A longitudinal 1 mm × 10 mm defect was created at the base of the lateral aspect of the penis. A TachoSil patch (Takeda, Japan) was applied to the defect. The penile skin covering was then restored. At 2 months, the rat penis was excised and examined with hematoxylin, eosin, and trichrome stains. We conducted a literature review of penile grafts in animals for comparison. Results: Rats weighed 369.2 gm (standard deviation: 31.5). At 2 months, all rats showed normal-looking penis with complete healing, no scaring, tethering, or gross inflammatory features. Histopathology of the patch site showed fibrosis, chronic inflammation, and foreign body giant cell reaction. There was no generation of a new TA, or new vascularity. No inflammatory or pathological reaction affected the underlying corpus cavernous tissue. One rat died on the 6th postoperative day. Postmortem showed massive multiorgan hemorrhage consistent with disseminated intravascular coagulopathy (DIC). Unlike some other reported grafts, there is no TA regeneration. Conclusions: TachoSil patching of penile TA defect forms a distinctive barrier against inflammation, protecting the underlying corpus cavernosum. However, no regeneration of the tunica defect is observed at 2 months. DIC is a potential complication of systemic absorption of TachoSil.

Micro-dissection testicular sperm extraction in Klinefelter's syndrome patients, King Faisal Specialist Hospital and Research Center, Riyadh experience.

BACKGROUND: In Klinefelter's syndrome patients with azoospermia, microscopic testicular sperm extraction (m-TESE) can be proposed as a therapeutic option. AIM OF STUDY: The aim of this study is to assess the sperm retrieval rate in patients with Klinefelter syndrome in King Faisal Specialist Hospital, Riyadh. METHODOLOGY: Retrospective, Chart review of 32 patients with Klinefelter syndrome who underwent m-TESE were reviewed and analyzed. All patients had two sets of semen analysis after 3 - 5 days abstinence of ejaculation with further study of semen by in vitro fertilization (IVF) wash. The hormonal analysis was studied. Ultrasonography of testes was assessed preoperatively. Testicular tubules were sent to the IVF laboratory and were studied under the microscope looking for sperms. Some testicular tissues were sent for the histopathology diagnosis. RESULTS: Patients' mean age was 34.9 ± 6.0 years. Mean hormonal levels of E2, FSH, LH, prolactin, and testosterone were 96.0 ± 22.0 pmol/L, 29.8 ± 5.4 IU/L, 19.0 ± 2.9 IU/L, 15.4 ± 3.6 ug/L, and 10.0 ± 1.9 nmol/L, respectively. There were two mosaic Klinefelter syndrome patients (6.25%), whereas 30 patients had a nonmosaic form (93.75%). The overall sperm retrieval rate was 37.5%. All patients had small bilateral testes. Sperm retrieval was successful in three patients with hypospermatogenesis, one patient with maturation arrest, and 8 patients with Sertoli-cell-only pattern. Four patients with complete hyalinization of testicular tissues had complete failure to retrieve sperms. The pregnancy rate after intra-cytoplasmic sperm injection was 50%. CONCLUSIONS: The sperm retrieval rate in Klinefelter syndrome patients with m-TESE is in accordance with most of those reported in the literature. Regarding histopathology, hypo-spermatogenesis showed a favorable outcome. The pregnancy rate with intra-cytoplasmic sperm injection was 50%.

The yield of microscopic varicocelectomy in men with severe oligospermia.

INTRODUCTION: Varicocele is detected in 35%-50% of men with primary infertility and up to 81% with secondary infertility. Various studies have shown that varicocele is related to testicular hypotrophy and impaired spermatogenesis. The effect of varicocelectomy in mild-to-moderate male factor infertility has been well reported. However, only a few studies addressed the impact of varicocelectomy in severe oligospermia. METHODS: We included 45 patients with severe oligospermia (<5 million/mL) who underwent microsurgical varicocelectomy between May 2014 and November 2017. Results of semen analysis taken at 6 months after varicocelectomy were compared and patients were divided into responders and nonresponders. Chi-square was used to compare the preoperative and postoperative sperm count, motility, and volume. RESULTS: After 6 months only one patient was found to be a responder with a pre- to post-operative motility of 45%-74% and a sperm concentration of 1 million/mL to 28.1 million/mL. There was a significant improvement in the mean sperm concentration after varicocelectomy which improved from 1.31 million/mL to 5.32 million/mL. However, a significant decrease in sperm motility was noted which decreased from 35.62% to 28.64% postoperatively. Postoperative semen volume increased from 2.56 mL to 3.19 mL, but this difference was not found to be statistically significant (P > 0.05). Four patients (8.9%) were found to have azoospermia after a 6-month follow-up. In these four patients who turned azoospermic had count <50,000 sperm/mL, two of them had a history of cryptospermia before varicocelectomy. Ejaculate sperm returned in two of these four patients in long-term follow-up (>6 months). CONCLUSION: The magnitude of improvement after microsurgical varicocelectomy for severely oligospermic patients is less profound than reported in mild male factor infertility.

Primary infertility secondary to a hidden posterior urethral valve representing a diagnostic challenge in the fifth decade.

Posterior urethral valves (PUVs) are frequently recognized during the perinatal period. Delayed diagnosis is reported usually within the first decade of life with diverse clinical presentations. In the current case report, we describe a 45 years old man patient who presented with aspermia and primary infertility for 8 years in whom his diagnostic workup revealed radiological imaging suggestive of PUVs. This phenomenon was confirmed by cystourethroscopy that showed obstructive valve. Endoscopic ablation resulted in significant improvement of his seminal parameter with successful conception.

Microdissection testicular sperm extraction: Overall results and impact of preoperative testosterone level on sperm retrieval rate in patients with nonobstructive azoospermia.

OBJECTIVE: The main objective is to review the overall result and impact of preoperative testosterone level on sperm retrieval rate (SRR) by microdissection testicular sperm extraction (micro-TESE) in patients with nonobstructive azoospermia (NOA). MATERIALS AND METHODS: We retrospectively reviewed the files of patients who underwent micro-TESE for NOA from August 2013 to December 2014. All patients were evaluated with history, physical examination, and hormonal assessment. Patients who had previous micro-TESE, obstructive azoospermia, or who took hormone therapy were excluded from the study. Patients were classified into two groups. Group A included patients who had low testosterone (<10 nmol/L), and Group B included patients with normal testosterone (>10 nmol/L). The primary endpoint was to review the overall results of the procedure and the impact of preoperative testosterone level on sperm retrieval. RESULTS: A total of 264 patients with NOA underwent micro-TESE. Group A included 133 patients with low testosterone (<10 nmol/l) with a median age of 36 ± 6.59 years, and Group B included 131 patients with normal testosterone (>10 nmol/L) with a median age of 33 ± 7.88 years (P = 0.1350). There was no significant difference in follicle-stimulating hormone (P = 0.2467), luteinizing hormone (P = 0.1078), prolactin (P = 0.5619), and testicular volume (P = 0.4052), whereas a significant difference was found in testosterone level (P = 0.0001) in both groups. Overall, sperm were successfully retrieved in 48.8% of men. SRR in Group B was significantly higher (57.25%) than that in Group A (40.60%) (P = 0.0068). SRR in patients with Sertoli-cell-only pathology was 30.35%, hypospermatogenesis was 89.74%, and maturation arrest was 32.43%. CONCLUSION: Micro-TESE is a successful and safe procedure in NOA patients with a poor prognosis. Preoperative testosterone level has a significant impact in the SRR by micro-TESE.

The Risks of Renal Angiomyolipoma: Reviewing the Evidence.

Renal angiomyolipoma (RAML), though a rare benign tumor, may impose a significant morbidity or even mortality due to its unique characteristics and the complications subsequent to its treatment. The classic tumor variant is composed of smooth muscular, vascular, and fatty components. The most straightforward diagnosis is when the fat component is abundant and gives a characteristic appearance on different imaging studies. In fat-poor lesions, however, the diagnosis is difficult and presumed a renal cell carcinoma. Yet, some variants of RAML, though rare, express an aggressive behavior leading to metastasis and mortality. The challenge lies in the early detection of benign variants and identifying aggressive lesions for proper management. Another challenge is when the vascular tissue component predominates and poses a risk of hemorrhage that may extend to the retroperitoneum in a massive life-threatening condition. The predicament here is to identify the characteristics of tumors at risk of bleeding and provide a prophylactic treatment. According to the clinical presentation, different treatment modalities, prophylactic or therapeutic, are available that span the spectrum of observation, embolization, or surgery. Renal impairment may result from extensive tumor burden or as a complication of the management itself. Improvement of diagnostic techniques, super-selective embolization, nephron-sparing surgery, and late treatment with the mammalian target of rapamycin inhibitors have provided more effective and safe management strategies. In this review, we examine the evidence pertaining to the risks imposed by RAML to the patients and identify merits and hazards associated with different treatment modalities.

Is survival after radical cystectomy for bladder cancer in Saudi patients different from that of Western patients?

BACKGROUND: Although radical cystectomy (RC) is considered the gold standard treatment of muscle invasive bladder cancer, nearly half of patients develop metastases and ultimately die within 2 years. OBJECTIVE: To assess survival, evaluate different prognostic factors that may affect disease-free survival (DFS) in Saudi patients after RC for carcinoma of the bladder and to compare our results with those of Western countries. DESIGN: Retrospective chart review. SETTING: A tertiary care center in Saudi Arabia. PATIENTS AND METHODS: We collected data on patients who underwent RC for bladder cancer in the period between 1979 and 2014. Demographic, clinical and pathological variables and the application of perioperative chemotherapy were reviewed. Univariate and multivariate analyses were done with DFS as the end point. MAIN OUTCOME MEASURE: Disease-specific survival. RESULTS: On 328 patients for whom data was available, the median follow up was 23 months (range, 2 month-28 years) and median age was 58 years (range, 21-90). Of these patients, 268 were males (81.7%), 235 (71.7%) had urothelial carcinoma (UC), 79 (24.1%) had squamous cell carcinoma (SCC), and 208 (63.4%) had pathological tumor stage 3 or more. The 5-year overall survival (OS) and DFS were 52% and 48%, respectively. There was no statistically significant difference in DFS of patients with UC and pure SCC. On univariate analysis, lymph node status and pathological tumor stage were significant predictors of DFS. Both variables sustained statistical significance in a multivariate analysis. CONCLUSION: Survival following RC is almost the same as others. Moreover, pathological tumor stage and lymph node metastasis were the only independent predictors for survival following RC. Future cooperative prospective studies are required to gain data on our region. LIMITATIONS: Relatively small sample size and retrospective.

Serum testosterone levels and other determinants of sperm retrieval in microdissection testicular sperm extraction.

BACKGROUND: Microdissection testicular sperm extraction (microTESE) has become the standard of care for sperm retrieval in non-obstructive azoospermia (NOA) patients. Understanding the significant determinants of microTESE outcomes may result in improvements in sperm retrieval rates and provide better-informed clinical decisions. METHODS: This is a clinical retrospective study conducted through chart review of 421 NOA patients who underwent microTESE between August 2009 and July 2015 in a tertiary-care referral hospital. Clinical, biochemical and histopathological characteristics were collected. Normal serum testosterone level was defined as testosterone >9.9 nmol/L. Multiple logistic regression was used to identify determinants of microTESE in the studied population. A P<0.05 was considered significant. RESULTS: Sperms were successfully retrieved in 39.4% of cases. The average testosterone level was 11.51±7.40 and 11.67±6.42 in patients with successful and unsuccessful microTESE, respectively (P=0.820). No significant association was found between serum testosterone level and sperm motility and amount. Of all variables, histological subtype remained to be the most significant determinant of microTESE outcomes in the examined population, with hypospermatogenesis having over a 3-fold higher odd of successful microTESE than sertoli-cell only. CONCLUSIONS: Serum testosterone level appears to have no significant association with microTESE outcomes in NOA. The underlying histological pattern is a significant determinant of the procedure's success.

The impact of renal angiomyolipoma on estimated glomerular filtration rate in patients with tuberous sclerosis complex.

BACKGROUND: There is a growing concern that renal impairment may develop in patients with renal angiomyolipomas (AMLs) associated with tuberous sclerosis complex (TSC) as a consequence of the disease itself and/or the interventions to mitigate the risk of hemorrhage. OBJECTIVE: To assess the estimated glomerular filtration rate (eGFR) in patients with bilateral renal AMLs and the impact of tumor burden and intervention on renal function. DESIGN: Retrospective study. SETTING: Urology department of a tertiary care hospital. PATIENTS AND METHODS: All adult patients (>=18 years of age) with TSC-associated renal AMLs seen from October 1998 to June 2015. We included only patients with bilateral tumors or solitary kidneys at the last follow-up. MAIN OUTCOME MEASURES: The eGFR, renal volume, and number and type of interventions. RESULTS: We identified 12 patients (median age 27.6, interquartile range 23.7-39.9 years), a median follow-up period of 1266 days (33-3133), and a median renal size of 454.7 mL (interquartile range 344.7-1016.9 on the right side; 558.1 mL, interquartile range 253.7-1001.4 on the left). In 11 (91.7%) patients, the eGFR was > 60 mL/min/1.77 m2. Six patients had three total nephrectomies, one had a contralateral partial nephrectomy, and seven had selective arterial embolizations. Intervention was associated with a significantly reduced eGFR. The renal size did not correlate with the eGFR. CONCLUSIONS: TSC-associated renal AMLs may attain a large size but normal renal function is maintained in 92% of patients. Interventions to mitigate the risk of hemorrhage are associated with decreased renal function. LIMITATIONS: The renal size was used as a surrogate for tumor size. Other limitations were the limited number of patients and lack of split renal function testing.

Scrotal Abscess Precipitating Late Infection of a Malleable Penile Prosthesis: The Risk Never Evanesces.

Although infrequent, infections represent the dreadful complication of penile prosthesis implantation. The incidence substantially decreases after a few infection-free postoperative months. We report herein a case of a very late penile prosthesis infection from a fistualizing scrotal abscess in a 67-year-old man. The patient presented with a one-month history of persistent penile-base discharge from a right hemiscrotal swelling. On examination, mild penile tenderness and a discharging penoscrotal-junction sinus were noted. Microbiological wound culture was positive for Staphylococcus epidermidis. Magnetic resonance imaging revealed this multiloculated fluid collection's communication with the right corporal body. Removal of the prosthesis was performed. Pathological evaluation of the dissected fistula was suggestive of acute on top of chronic inflammatory reactions. To our knowledge, this is the first report of a scrotal abscess leading to penile prosthesis infection 15 years after an uneventful implantation.

Penile autotransplantation in rats: An animal model.

CONTEXT: Penile allotransplantation might be a viable option for patients who need penile reconstruction. AIMS: A successful autotransplantation rat model is the first step toward proceeding for allotransplantation. We herein evaluate autotransplantation following transaction of the rat penis just distal to the urethral bulb. SETTINGS AND DESIGN: Experimental animal study. MATERIALS AND METHODS: Five Sprague-Dawely rats weighing 520 g (SD 19) were used. Utilizing a magnification of 6-40, transection and immediate anastomosis of the tunica albuginea, urethra, dorsal vein and nerves were carried out. Vesicostomy was made to divert urine. The glandular skin was sutured to the perineum and the abdominal wall was closed in layers. STATISTICAL ANALYSIS USED: Descriptive statistics. RESULTS: Average surgery time was 8 h. The first two rats had no vesicostomy and died in the first postoperative day from retention. Three rats tolerated well the procedure and survived to the end point. One rat was sacrificed at day 10 and histopathology showed 30-50% necrosis of the implanted penis. Another rat was sacrificed at day 20 and showed normal cavernous tissue. The fifth rat was sacrificed 3 months postoperatively and showed evidence of moderate corporal fibrosis. Urethral fistula and necrosis of corpus spongiosum, dorsal nerve necrosis and dorsal vein occurred in all animals. CONCLUSIONS: Penile autotransplantation in rats is feasible and provides the basis for evaluation of the corpora cavernosa in an allotransplantation model. Long-term urethral continuity and dorsal neurovascular bundle survival in this model is difficult to establish.

Co-administration of intravesical bacillus Calmette-Guérin and interferon α-2B as first line in treating superficial transitional cell carcinoma of the urinary bladder.

OBJECTIVE: • To evaluate the efficacy and toxicity of the combination of bacillus Calmette-Guérin (BCG) and interferon α-2B (IFNα-2B) in treating superficial bladder cancer (SBC). The mentioned combination has shown synergism in pre-clinical studies. PATIENTS AND METHODS: • The present study is a single-arm, open-label, single-institution prospective trial. Patients with Ta, T1 or in situ carcinoma and no previous intravesical therapy were included between July 2002 and June 2009. • Patients were treated with weekly intravesical instillation of 27 mg of BCG mixed with 10 million units (MU) of IFNα-2B for six consecutive weeks followed by 3-weekly booster instillations at 3 months if there was no recurrence. • The primary endpoint was disease recurrence. Secondary endpoints were disease progression and toxicity. • Patients were followed-up with cystoscopy and urine cytology every 3 months. RESULTS: • In all, 50 patients were included. • At a median follow-up of 55.8 months, 31 (62%) patients were recurrence-free. • Progression to muscle invasion occurred in two (4%) and metastasis occurred in two (4%) patients. • Treatment was well tolerated, with grade III dysuria and frequency occurring in 18 and 14% of patients, respectively, and with 74% of patients being able to complete the maintenance dosage. CONCLUSION: • The combination of BCG and IFNα-2B in the patient population with SBC has similar efficacy and toxicity to BCG monotherapy.

Changing trends in presentation, diagnosis and management of renal angiomyolipoma: comparison of sporadic and tuberous sclerosis complex-associated forms.

OBJECTIVES: To evaluate the changing management of sporadic renal angiomyolipoma and renal angiomyolipoma associated with the tuberous sclerosis complex (TSC) during the past 16 years. METHODS: We retrospectively reviewed the charts of 60 patients with angiomyolipoma seen at our institutions. RESULTS: The median age at presentation was 45 years (range 7-78). The presentation was pain in 30 patients and hematuria in 13; it was incidentally discovered in 17 patients. Of the 60 patients, 43 were females. TSC was present in 14 patients. The median tumor size was 4 cm (range 0.3-40, mean 6.5 +/- 1.1). Of the 60 patients, 31 were followed up expectantly. Surgery or intervention was needed for 29 patients to control hemorrhage or relieve pain or because of the suspicion of malignancy. Of these 29 patients, 12 underwent nephrectomy, 11 partial nephrectomy, and 6 embolization. The patients treated for hemorrhage had a median tumor diameter of 11 cm (range 2-21). Patients were followed up for a mean of 39.3 +/- 5.4 months. The lesions grew an average of 4.7 +/- 3.4 cm for TSC tumors and 0.6 +/- 0.2 cm for sporadic angiomyolipoma tumors. None of the patients developed renal impairment. Patients with TSC presented at a younger age, had larger and bilateral lesions, and were more symptomatic during follow-up. In the past 6 years, a significant trend was seen toward finding tumors in asymptomatic patients and toward the use of conservative or interventional (embolization) treatment. CONCLUSIONS: Renal angiomyolipoma has a slow growth rate. The preservation of renal function was noted in all our patients. A recent shift was noted toward finding smaller tumors in asymptomatic patients and the use of conservative and interventional treatment.

Outcome of penile cancer in circumcised men.

PURPOSE: We previously reported on a group of patients with post-circumcision carcinoma of the penis. We now study the long-term outcome of these patients. MATERIALS AND METHODS: We retrospectively reviewed the available charts of 22 patients presenting between October 1979 and May 2000. RESULTS: Of 22 patients 18 underwent ritual circumcision with extensive scar development. Median age at diagnosis was 62.4 years. The penile lesion was dorsal and proximally located in 15 patients. Median delay before diagnosis was 12 months. Clinically 14 patients had stage T1-T2 disease, with 13 having no lymph node involvement and none with distant metastasis, 8 patients had stage T3-T4 disease. A total of 15 patients were treated surgically with total penectomy (10) or conservative local excision (5), inguinal lymph node dissection (9) and subsequent penile reconstruction (3). Pathological staging in 15 patients revealed 10 patients with stage T1 and in 8 patients with lymph node dissection none had nodal metastasis. Histopathological classification was 20 squamous cell carcinoma, 1 sarcoma and 1 verrucous carcinoma. Six patients refused surgery and 1 was referred for palliation. Median followup was 14.5 months and median survival was 14.5 months. The 3-year survival was 42% for stage T1-T2 and 13% for T3-T4 (p = 0.0052). Median survival for the surgical group was 34 months whereas for nonsurgical group was 3 months (p = 0.0016). Recurrence-free survival in the surgical group was 50%. CONCLUSIONS: Penile carcinoma in circumcised men is a distinct disease commonly following nonclassic vigorous circumcision. Delayed diagnosis and deferring surgical treatment are associated with increased mortality.

The acceptance and satisfaction of Saudi males to vasoactive autoinjection intracavernous therapy, external negative pressure device and penile prosthesis in the treatment of erectile dysfunction.

BACKGROUND: The aim of the study was to determine the acceptance and satisfaction of Saudi impotent male patients to intracavernous vasoactive autoinjection therapy, external negative pressure device and penile prosthesis insertion in the treatment of their impotence. SUBJECTS AND METHODS: The medical records of 210 Saudi patients who presented with erectile dysfunction and were offered intracavernous vasoactive autoinjection therapy, external negative pressure device or penile prostheses for the treatment of their erectile dysfunction were retrospectively analyzed to determine the acceptance and satisfaction of their selected treatment modalities. RESULTS: Intracavernous vasoactive autoinjection therapy was the most acceptable treatment option, followed by negative pressure device, and then insertion of penile prosthesis. About 11.9% of patients refused all treatment options. Only 40% and 12% of patients who were treated with intracavernous vasoactive autoinjection therapy and external negative pressure device, respectively, were satisfied with their treatment modality. After one year of follow-up, insertion of penile prosthesis had the highest satisfaction rate among the treatment modalities, with 92% and 87% of patients being satisfied at 3 and 12 months' follow-up, respectively. CONCLUSION: Intracorporeal vasoactive autoinjection therapy had the highest acceptance rate compared with external negative pressure devices and penile prosthesis, however, it had low satisfaction rate and the dropout rate was high. External negative pressure devices are generally poorly accepted and are rarely satisfactory in our patient population. Penile prosthesis insertion is poorly accepted, however, it has the highest satisfaction rate. Such information will allow patients under treatment for impotence and their treating physicians to make better, educated choices on the mode of treatment.

Isolation and staging of horse seminiferous tubules by transillumination.

Stages of the spermatogenic cycle in the horse were determined by trans-illumination of enzymically isolated, seminiferous tubules and were verified by whole-mounted tubules observed by Nomarski optics and by conventional histology. Isolated tubules were obtained from young (less than 2 years) and adult (4-10 years) horses by enzymic digestion. Dispersed tubules were separated into three different groups based on the presence, size, and intensity of a dark region in the centre of the tubules: (1) pale--homogeneously light, (2) spotty--light on the periphery with a wide spotty region in the central two-thirds, or (3) dark--an intensely dark, narrow region through the central one-third. Seminiferous tubules from young stallions separated easily, but were only of the homogeneously light pattern as they lacked mature spermatids. After observation by Nomarski optics and bright-field microscopy, pale tubules under transillumination largely contained Stages I and II, spotty tubules contained Stages V and VI, and dark tubules contained Stages VII and VIII of the spermatogenic cycle. In-vitro incorporation of [3H]thymidine in spermatogonia and preleptotene/leptotene primary spermatocytes of these tubules confirmed the viability of germ cells in isolated tubules, and ultrastructural analysis confirmed excellent preservation of normal structure of seminiferous epithelium in isolated tubules. Hence, segments of seminiferous tubules in specific stages of the spermatogenic cycle can be obtained from enzymically digested horse testes when viewed by transillumination.