Intrasurgical parameters associated with successful sperm retrieval in patients with non-obstructive azoospermia undergoing salvage microdissection testicular sperm extraction.

BACKGROUND: Patients with non-obstructive azoospermia with a previously failed conventional testicular sperm extraction may undergo a salvage microdissection testicular sperm extraction with the probability of successful sperm retrieval being almost dependent upon the number of previous surgical attempts and to different histopathologic categories. OBJECTIVES: To determine whether the seminiferous tubules pattern and the histological categories could affect the sperm retrieval rate in patients with non-obstructive azoospermia undergoing salvage microdissection testicular sperm extraction after failed conventional testicular sperm extraction. MATERIALS AND METHODS: Seventy-nine patients undergoing unilateral or bilateral salvage microdissection testicular sperm extraction were evaluated. During microdissection testicular sperm extraction, if present, dilated tubules were retrieved, otherwise, tubules with slightly larger caliber than that of the surroundings were removed. When no dilated tubule or tubule with slightly larger caliber was found, not dilated tubules were excised. A prediction model was built with seminiferous tubules pattern and testis histology as covariates. RESULTS: Sperm retrieval was successful in 30 out of 79 patients. The prediction model correctly classified 88.3% of cases, explained the 29.7% variability of the outcome, and significantly predicted the microdissection testicular sperm extraction outcome with a sensitivity of 67.7% and a specificity of 90.2%, Both tubules with slightly larger caliber and not dilated tubules were negatively associated with the chance of retrieving spermatozoa. Among the histological categories, only early maturation arrest was significant to the model (log(SSR) = 0.57 - 1.9SDT - 3.3NDT - 1.76EMA) (where SSR is sperm retrieval rate, SDT is tubule with slightly larger caliber, NDT is not dilated tubule, and EMA is early maturation arrest). The model had a clearly useful discrimination (area under the curve = 0.814), the estimated performance was 0.8105, and internal calibration was acceptable (p > 0.05). DISCUSSION: Seminiferous tubules pattern and testis histology may reliably explain the salvage microdissection testicular sperm extraction outcome in all patients with non-obstructive azoospermia apart from those with early maturation arrest, where the homogeneous apparent seminiferous tubules pattern may be misleading. CONCLUSION: The outcome of salvage microdissection testicular sperm extraction can be predicted by the same intrasurgical parameters that have been demonstrated to predict the outcome of microdissection testicular sperm extraction in naïve patients with non-obstructive azoospermia.

Ultrasonographically determined size of seminiferous tubules predicts sperm retrieval by microdissection testicular sperm extraction in men with nonobstructive azoospermia.

OBJECTIVE: To investigate the value of the ultrasonographically determined size of seminiferous tubules and other conventional parameters for predicting sperm retrieval by microdissection testicular sperm extraction (micro-TESE). DESIGN: Clinical retrospective study. SETTING: Two urological clinics. PATIENT(S): Eight hundred six men with nonobstructive azoospermia. INTERVENTION(S): Micro-TESE. MAIN OUTCOME MEASURE(S): Sperm retrieval. RESULT(S): Sperm retrieval was successful in 240 (29.8%) of the 806 men. In a receiver operating characteristic analysis of sperm retrieval, the area under the curve (AUC) for seminiferous tubules, assessed as 0, 100, 200, 250, or 300 µm, was no less than 0.82 (95% confidence interval [CI] 0.79-0.85). Sensitivity and specificity at a cutoff point of 250 µm were 76.7% and 80.7%, respectively. An AUC of 0.85 (95% CI, 0.81-0.88) was attained in a parsimonious multiple logistic regression model that included age (<30, 30-39, and 40-59 years), low follicle-stimulating hormone (<14 IU/L), history of cryptorchidism, and sex chromosome abnormality in addition to the diameter of seminiferous tubules. CONCLUSION(S): The gray-scale image in testicular ultrasound was shown to be highly predictive of sperm retrieval in micro-TESE in a large series of men with nonobstructive azoospermia.

Intratubular Teratoma: A Rare Form of Testicular Germ Cell Neoplasia.

Germ cell neoplasia in situ is the initial manifestation for invasive germ cell tumor. Further progression will result in intratubular germ cell tumor with the majority being intratubular seminoma or intratubular embryonal carcinoma. Intratubular teratoma in the testis is exceptionally rare with no well-documented cases to our knowledge. In this article, we report a case of an intratubular teratoma adjacent to mixed germ cell tumor in the testis. The patient is a 34-year-old male who presented with a palpable right testicular mass and underwent right radical orchiectomy. Gross examination of the testis revealed 2.0-cm tan, well-circumscribed, firm, and nodular mass at the inferior pole. Microscopic examination revealed a mixed germ cell tumor, predominantly seminoma (95%) with embryonal carcinoma (4%) and teratoma (1%). There is also germ cell neoplasia in situ, intratubular seminoma, and intratubular teratoma at the periphery of the tumor. Tubules with intratubular teratoma were filled by neoplastic squamous cells with a single layer of germ cell neoplasia in situ at the periphery. Adjacent to the intratubular teratoma was seminoma, embryonal carcinoma, and invasive teratoma. Immunohistochemical stains showed the neoplastic squamous cells in the tubule to be positive for p40 and negative for OCT34 and D2-40. The single layer of germ cell neoplasia in situ at the periphery of the intratubular teratoma was negative for p40 and positive for OCT34 and D2-40. Although teratoma is a common component in an adult germ cell tumor, an intratubular manifestation is exceptional. The present case illustrates this rare finding.

Stereological and morphological analysis of the effects of aging on spermatogenesis in rat testis 1.

PURPOSE: To quantify, through stereological and morphometric analysis, spermatogenesis in rats undergoing the natural aging process. METHODS: Seventy-two male Wistar rats were divided into 6 equal groups according to age at the time of killing: 3, 6, 9, 12, 18, and 24 months. All the rats were subjected orchiectomy and collection of testicular parenchymal fragments for histological and morphometric analysis. The numerical density of spermatids was calculated using a stereological study, and morphometric analysis was conducted to measure the height of the germinal epithelium and the area of the seminiferous tubules. RESULTS: We found that the 18 and 24 months groups showed a significant reduction in the number of round spermatids. However, the height of the germinal epithelium was not significantly different between the groups. The area of seminiferous tubules was also significantly reduced in the elderly rats compared to that in the young ones. CONCLUSION: Aging of rats showed a significant reduction in the number of round spermatids and the area of the seminiferous tubules, more pronounced in the rats at 18 and 24 months of life.

Stereological and morphological analysis of the effects of aging on spermatogenesis in rat testis

Abstract Purpose: To quantify, through stereological and morphometric analysis, spermatogenesis in rats undergoing the natural aging process. Methods: Seventy-two male Wistar rats were divided into 6 equal groups according to age at the time of killing: 3, 6, 9, 12, 18, and 24 months. All the rats were subjected orchiectomy and collection of testicular parenchymal fragments for histological and morphometric analysis. The numerical density of spermatids was calculated using a stereological study, and morphometric analysis was conducted to measure the height of the germinal epithelium and the area of the seminiferous tubules. Results: We found that the 18 and 24 months groups showed a significant reduction in the number of round spermatids. However, the height of the germinal epithelium was not significantly different between the groups. The area of seminiferous tubules was also significantly reduced in the elderly rats compared to that in the young ones. Conclusion: Aging of rats showed a significant reduction in the number of round spermatids and the area of the seminiferous tubules, more pronounced in the rats at 18 and 24 months of life.

Heterogenicity of testicular histopathology and tubules as a predictor of successful microdissection testicular sperm extraction in men with nonobstructive azoospermia.

Only a few studies evaluate the presence of spermatozoa intraoperatively. The study aimed to assess whether the heterogenicity of testicular histopathology and seminiferous tubules can predict the outcome of microdissection testicular sperm extraction (micro-TESE) in men with nonobstructive azoospermia (NOA).The study comprised a retrospective analysis of 94 patients with azoospermia who were referred from 2016 to 2017. Under optical magnification, they were classified into 2 groups based on the diameter of tubules intraoperatively, namely homogeneous tubules and heterogeneous tubules. Postoperatively, patients were divided into 2 groups of heterogeneous histopathology and homogeneous histopathology according to the 8 histopathological classification subgroups. The sperm retrieval rate was the main outcome.Testicular spermatozoa were successfully retrieved in 27 men (28%). The sperm retrieval rate in those with heterogeneous histopathology was higher than men with homogeneous histopathology (47% vs 12%; P < .001). The sperm retrieval rate of each histopathological subgroup in men who had the heterogeneous histopathology was higher, compared with the homogeneous histopathology (Sertoli cell only [SCO]: 30% vs 6%; maturation arrest [MA]: 38% vs 0%; tubular hyalinization: 42% vs 20%, respectively). Under the optical magnification, the sperm retrieval rate was significantly higher in men with heterogeneous vs homogeneous tubules (65% vs 15%, P < .001). Moreover, the sperm retrieval rate of the contralateral testicular was higher in men who had heterogeneous tubules, compared with the homogeneous tubules (25% vs 3%; P = .036).Heterogenicity of histopathology is an effective predictor in men with histopathological information available from a previous diagnostic biopsy or conventional TESE attempt preoperatively for successful sperm retrieval. Homogeneous tubules seem beneficial for some patients to perform a limited (superficial) contralateral micro-TESE after no spermatozoa were identified initially.

Primate Primordial Germ Cells Acquire Transplantation Potential by Carnegie Stage 23.

Primordial germ cells (PGCs) are the earliest embryonic progenitors in the germline. Correct formation of PGCs is critical to reproductive health as an adult. Recent work has shown that primate PGCs can be differentiated from pluripotent stem cells; however, a bioassay that supports their identity as transplantable germ cells has not been reported. Here, we adopted a xenotransplantation assay by transplanting single-cell suspensions of human and nonhuman primate embryonic Macaca mulatta (rhesus macaque) testes containing PGCs into the seminiferous tubules of adult busulfan-treated nude mice. We discovered that both human and nonhuman primate embryonic testis are xenotransplantable, generating colonies while not generating tumors. Taken together, this work provides two critical references (molecular and functional) for defining transplantable primate PGCs. These results provide a blueprint for differentiating pluripotent stem cells to transplantable PGC-like cells in a species that is amenable to transplantation and fertility studies.

[IMMUNOHISTOCHEMICAL EXPRESSION OF UBIQUITIN PROTEIN IN PERITUMORAL TISSUE OF PATIENTS WITH TESTICULAR GERM CELL TUMORS].

For the purpose of definition of features immunohistochemical expression of protein Ubiquitin in peritumoral testicular tissue, which can be characterised as precancerous changes, the 40 patients with testicular germ cell tumors are investigated. In peritumoral testicular tissue in patients with disturbance of spermatogenesis. which make 95 %, it is taped: intensifying in seminiferous tubules of ubiquitination processes, testifying about intensive proteolysis of considerable quantity of the damaged intracellular proteins, occurrence of atypical germ cells (TIN), which differ from normal spermatogenesis cells authentically lower of nuclear and cytoplasmatic expression of protein Ubiquitin, and also disturbance of ubiquitination processes in Leydig cells in the form of intensifying of cytoplasmatic expression and total disappearance of nuclear expression of protein Ubiquitin. The received results testify to the important role of structural and functional disturbances of ubiquitin-proteolysis system components at the initial stages of testicular tissue carcinogenesis.

Testicular feminization: complete androgen insensitivity syndrome. Discussions based on a case report.

INTRODUCTION AND OBJECTIVES: Testicular feminization is the syndrome when a male, genetically XY, because of various abnormalities of the X chromosome, is resistant to the actions of the androgen hormones, which in turn stops the forming of the male genitalia and gives a female phenotype. The androgen insensitivity syndrome occurs in one out of 20,000 births and can be incomplete (various sexual ambiguities) or complete (the person appears to be a woman). The aim of this paper is to present the diagnosis and treatment of a case of testicular feminization. PATIENT AND METHODS: A 22-year-old patient is admitted at Gynecology for primary amenorrhea. The clinical examination shows a female phenotype: the breasts are normally developed, but there is no hair in the groins and axillary areas, the labia are small and hypoplastic, the urinary meatus is normally inserted, and the vulva is unpigmented. The gynecological exam reveals that the hymen is present, the vagina has 1.5 cm in length, while the uterus is absent. At Endocrinology, the levels of gonadotropins were measured and found normal (FSH 3.18 mU/mL, LH 15 mU/mL), the progesterone was 5.79 nmol/L, estradiol was 82.39 pmol/L and the testosterone was 4.27 nmol/L. The karyotype was mapped in order to differentiate the androgen insensitivity syndrome from other genetic abnormalities, like the Klinefelter syndrome (46XXY), Turner syndrome (45XO), mixed gonadal dyssynergia (45XO/46XY) or tetragametic chimerism (46XX/46XY). These tests confirmed the suspected diagnosis - testicular feminization (46XY). The pelvic CT scan revealed the lack of uterus and ovaries, hypoplastic vagina, and intra-abdominal prepsoic testes. The testes were removed in order to avoid the malignant risk. We performed laparoscopic bilateral orchiectomy. RESULTS: Surgically, the patient had a simple evolution, being discharged in the second day postoperatory, and estrogen therapy was started from that moment on. Mentally, the patient kept thinking she was a woman, so the decision of telling her the truth was left to the parents. CONCLUSIONS: Testicular feminization is a rare disease that must be diagnosed and treated through close work between gynecologists, endocrinologists, geneticians, urologists, and psychiatrists. Bilateral laparoscopic orchiectomy is the best procedure to remove the intra-abdominal testes, in order to avoid their malignant transformation.

Ultrasonically actuated silicon-microprobe-based testicular tubule metrology.

We report on a microfabricated silicon microprobe integrated with an ultrasonic actuator and polysilicon strain gauges for Microdissection Testicular Sperm Extraction (TESE) surgery. Multiple microprobe insertion experiments were performed on rat testis tissue and, by monitoring the tubule puncture artifacts in the force signal sensed by the microprobe, we were able to estimate the average diameter of the sperm-carrying tubules in the sample. We have demonstrated the ability to sense the existence of larger tubules embedded in a mass of thinner tubules, by means of an Area-Ratio based metric using an analytically calculated expression for the distribution of sizes measured by the microprobe. This information is important in microdissection TESE to distinguish tubules with and without fertile sperm, potentially eliminating the large incision currently required for optical spermatazoa localization.

An ultrasonically actuated silicon-microprobe-based testicular tubule assay.

Microdissection testicular sperm extraction (TESE) is an invasive surgical procedure in which sparsely located healthy larger diameter tubules carrying viable spermatazoa are identified by visual examination of the seminiferous tubules of the infertile testis under a microscope, and biopsies of regions of interest are performed. In this paper, we report on microfabricated silicon microprobes integrated with an ultrasonic horn actuator and strain gauges for microdissection probe-TESE (MP-TESE) surgery. The microprobes, with axial-force-sensitive polysilicon strain gauges, have high force sensitivity (-0.4 V/N). The probes were used to detect the boundaries between seminiferous tubules, thus enabling identification of individual tubule diameters. Insertion experiments were performed on rat testis tissue, and by monitoring the tubule puncture in the recorded force, we were able to estimate the average diameter approximately 41.2 +/- 1.6 microm of the sperm-carrying tubules in samples. We have also demonstrated the ability to sense the existence of larger tubules embedded in a mess of thinner tubules, using an analytically calculated expression for the distribution of sizes measured by the microprobe. This information is important in MP-TESE to distinguish tubules with and without fertile sperm, potentially eliminating the large incision currently required for optical spermatazoa localization.

GC-1 mRHBDD1 knockdown spermatogonia cells lose their spermatogenic capacity in mouse seminiferous tubules.

BACKGROUND: Apoptosis is important for regulating spermatogenesis. The protein mRHBDD1 (mouse homolog of human RHBDD1)/rRHBDD1 (rat homolog of human RHBDD1) is highly expressed in the testis and is involved in apoptosis of spermatogonia. GC-1, a spermatogonia cell line, has the capacity to differentiate into spermatids within the seminiferous tubules. We constructed mRHBDD1 knockdown GC-1 cells and evaluated their capacity to differentiate into spermatids in mouse seminiferous tubules. RESULTS: Stable mRHBDD1 knockdown GC-1 cells were sensitive to apoptotic stimuli, PS341 and UV irradiation. In vitro, they survived and proliferated normally. However, they lost the ability to survive and differentiate in mouse seminiferous tubules. CONCLUSION: Our findings suggest that mRHBDD1 may be associated with mammalian spermatogenesis.

Report of 4 cases of testicular rupture in adolescent boys secondary to sports-related trauma.

Testicular rupture is a rare entity in children and adolescents. This is due to the smaller size of the testicles in these patients, the well-protected location of the testicles, and the high degree of mobility of these organs. We present 4 cases of testicular rupture occurring in preadolescent and adolescent boys over an 11-month period in a tertiary care pediatric emergency department.

Single tubule biopsy: a new objective microsurgical advancement for testicular sperm retrieval in patients with nonobstructive azoospermia.

OBJECTIVE: The aim of this study was to measure the diameter of seminiferous tubules (ST) during microdissection testicular sperm extraction (TESE) using a micrometer fixed to one of the eyepieces of the operating microscope to find a correlation between the extracted ST diameter and TESE outcome. DESIGN: A prospective comparative study. SETTING: Adam International Andrology and Infertility Clinic, Giza, Egypt. PATIENT(S): Two hundred sixty-four patients with nonobstructive azoospermia (NOA) were included. INTERVENTION(S): Patients underwent TESE using the open surgical technique. The STs were measured using the micrometer, and the tubule with the largest diameter was excised and freshly examined under an inverted microscope. If no spermatozoa were found, another sample was taken from the second most dilated tubule area and then at random until sperm were found or a maximum six samples were harvested. If no spermatozoa were detected, the contralateral testis was operated upon. MAIN OUTCOME MEASURE(S): The TESE outcome in relation to ST diameter. RESULT(S): The total sperm recovery rate was 105 out of 264 (39.8%). When ST measured >or=300 microm the sperm retrieval rate was 16 out of 19 (84.2%). When ST diameter was <300 microm, the sperm retrieval rate was 36.3% (89 out of 245). CONCLUSION(S): During microdissection TESE, the best cutoff level of the ST diameter for harvesting testicular spermatoza is 110 microm with sensitivity 86.0% and specificity 74.4% (AUC 0.653, 95% confidence interval 0.608-0.663). When ST diameter is 300 microm or more a single tubule biopsy is usually sufficient to harvest enough testicular spermatozoa for intracytoplasmic sperm injection or sperm freezing with minimal tissue excision.

[Extraperitoneal laparoscopic radical prostatectomy (report of 5 cases)].

OBJECTIVE: To discuss the clinical experience of laparoscopic radical prostatectomy by extraperitoneal approach. METHODS: Five patients with localized prostate cancer underwent laparoscopic radical prostatectomy by extraperitoneal approach. The surgical procedure included the excision of the prostate, seminal vesicles, ampulla ductus deferentis and part of the bladder neck, followed by urethrovesical anastomosis. RESULTS: All the operations were successful. The mean operation time was 350 minutes (ranging from 270 to 420 mm); the mean estimated blood loss was 480 ml (ranging from 250 to 600 ml). The bowel activity was recovered with 48 hours after surgery. The patients were ambulant between the 2nd and 3rd postoperative days. The mean hospital stay was 8. 5 days (ranging from 7 to 12 days). The 3-8 months follow-up found no incontinence of urine; of the 3 preoperatively potent patients, 2 were able to have sexual intercourse; strictured stoma was reported in only 1 case. CONCLUSION: The extraperitoneal laparoscopic radical prostatectomy, keeping the procedure out of the peritoneal cavity, with small incision and rapid recovery, may be considered as a promising surgical method for patients with localized prostate cancer.

Microsurgical single tubular epididymovasostomy: assessment in the era of intracytoplasmic sperm injection.

OBJECTIVE: To reevaluate the role of microsurgical single tubular epididymovasostomy for the treatment of obstructive azoospermia in the era of intracytoplasmic sperm injection (ICSI). DESIGN: Retrospective clinical study. SETTING: University infertility clinic. PATIENT(S): Sixty-one patients with obstructive azoospermia who underwent microsurgical single tubular epididymovasostomy. INTERVENTION(S): Microsurgical single tubular epididymovasostomy. MAIN OUTCOME MEASURE(S): The overall patency and live-birth rates and factors that influenced the surgical outcome. RESULT(S): The overall patency rate after surgery was 68.9% (42/61) and the live-birth rate 31.1% (19/61). Of the 19 live-birth cases, 11 were achieved by natural means and 2 were achieved by conventional IVF soon after the operation, then subsequently by natural conception. The remaining 6 were the result of conventional IVF after surgery. An analysis of the potential prognostic factors previously associated with epididymovasostomy indicated that none had a statistically significant correlation with surgical outcome. In cases of patency, the partners were stratified into a younger group (21-30 years; n = 12) and an older group (31-36 years; n = 30). There was no statistically significant difference between the groups in the live-birth rate regardless of the means of conception (natural versus conventional IVF). CONCLUSION(S): This study demonstrates that the results obtained by microsurgical single tubular epididymovasostomy are comparable to those obtained with the use of IVF and ICSI. Even in this era of ICSI, the option of microsurgical single tubular epididymovasostomy should be considered because ICSI involves surgery to retrieve sperm and complex invasive treatment of the wife.

Testicular sperm extraction by Trucut needle and milking of seminiferous tubules: a technique with high yield and patient acceptability.

OBJECTIVE: To assess the sperm yield and patient acceptability of Trucut needle testicular biopsy followed by seminiferous tubule milking. DESIGN: Prospective case analysis. SETTING: The Regional Fertility Center, Royal Maternity Hospital, Belfast, Northern Ireland, United Kingdom. PATIENT(S): Forty-one males with obstructive azoospermia (normal testicular volume and FSH and LH levels). INTERVENTION(S): Trucut needle testicular biopsies under local anesthetic with milking of the seminiferous tubules. MAIN OUTCOME MEASURE(S): Quantitation of sperm retrieved per biopsy core and patient follow-up by questionnaire. RESULT(S): A mean of 105,634 sperm (range, 5,000-427,800) were retrieved, and the mean biopsy weight was 9.17 mg. Twenty-six subjects found the biopsy painless and 15 were pain-free after biopsy. CONCLUSION(S): The Trucut needle can be used in combination with seminiferous tubule milking to obtain large numbers of sperm in men with obstructive azoospermia.

Sperm number and condition affect the number of basal cells and their expression of macrophage antigen in the murine epididymis.

Unilateral ligation of the mid-corpus epididymis, the proximal vas deferens and imposition of an abdominal temperature for 6 days as well as bilateral castration for 3, 6 or 14 days, resulted in a change in epithelial composition of the adult murine epididymis with regard to the number and antigen expression of basal cells. There were fewer basal cells per tubule cross-section with fewer expressing F4/80 antigen when spermatozoa were absent from the proximal lumen following short-term castration. Conversely, more basal cells with more of them demonstrating macrophage antigen expression were evident when more or damaged spermatozoa were in the proximal lumen after corpus ligation and exposure to abdominal temperature or in the cauda after long-term withdrawal of androgen support. By contrast, ligation of the vas deferens did not lead to tubule distension, and hence sperm accumulation, and did not alter the basal cell population in the cauda epididymis. The data suggest that epididymal basal cells respond in number and macrophage antigen expression to the presence of sperm autoantigens in the lumen with little dependence on circulating androgens. These changes may represent responses to minimise the interaction of sperm autoantigens with the immune system and the risk of immunological infertility.

Adenocarcinoma of the rete testis. Report of two cases.

Adenocarcinoma of the rete testis is extremely rare and has been the subject of only sporadic case reports. Its natural history appears highly malignant even in localized forms; because of a poor response to adjuvant therapy radical orchiectomy with retroperitoneal lymph node dissection is recommended in stage A. We report our experience with two examples which arose in men of 26 and 57 years of age between 1988 and 1999. Both of them presented with a scrotal mass, and one of them had hydrocele. Neither had a history of maldescendent, infections or trauma. Microscopically the tumors were adenocarcinomas, and the one in the 26 years old patient presented with tubulopapillary formations. Immunohistochemical staining demonstrated positivity for CK and NSE in the 26 year old patient and only a weak positivity for CEA and vimentin in the 57 year old one. EMA and calretinin were always negative. Both were stage A but the young man who underwent radical orchiectomy with no lymph node dissection, developed a lymph node metastasis within one year.

Germ cell transfer into rat, bovine, monkey and human testes.

Germ cell transplantation is a potentially valuable technique offering oncological patients gonadal protection by reinitiating spermatogenesis from stem cells which were reinfused into the seminiferous tubules. In order to achieve an intratubular germ cell transfer, intratubular microinjection, efferent duct injections and rete testis injections were applied on dissected testes of four different species: rat, bull, monkey and man. Ultrasound-guided intratesticular rete testis injection was the best and least invasive injection technique with maximal infusion efficiency for larger testes. Deep infiltration of seminiferous tubules was only achieved in immature or partially regressed testes. This technique was applied in vivo on two cynomolgus monkeys. In the first monkey a deep infusion of injected cells and dye into the lumen of the seminiferous tubules was achieved. In the second, transplanted germ cells were present in the seminiferous epithelium 4 weeks after the transfer. These cells were morphologically identified as B-spermatogonia and located at the base of the seminiferous epithelium. In summary, this paper describes a promising approach for germ cell infusion into large testes. The application of this technique is the first successful attempt of a germ cell transfer in a primate.