Vasectomy re-reversal: effectiveness and parameters associated with its success

ABSTRACT Introduction: When the vasectomy reversal (VR) fails, and the patient desires natural conception with his sperm, vasectomy re-reversal (VRR) is the only alternative. Purpose: To determine the VRR effectiveness and whether specific parameters can be associated with its success. Materials and Methods: We retrospectively evaluated 18 consecutive vasectomized patients, who had failed their VR through bilateral vasovasostomy, and posteriorly were submitted to VRR. The parameters of the study were: age of the patients, elapsed time between vasectomy and VRR (V-VRRt), elapsed time between VR and VRR (VR-VRRt), presence of spermatozoa in the proximal vas deferens fluid (SptzVDF) in the VRR and results of semen analysis after VRR (SA-VRR). Results: The mean of the age of the patients was 44.11±6.55 years (32.0-57.0), the mean of V-VRRt was 11.76±6.46 years (1.5-25.0) and the mean of VR-VRRt was 2.13±2.27 years (0.5-10.0). SptzVDF in the VRR were found bilaterally in 8 patients, unilaterally in 4 and absent in 6. SA-VRR demonstrated normozoospermia in 9 patients, oligozoospermia in 3 and azoospermia in 6, with patency rate of 66.67%. SA-VRR showed statistically significant dependence only with SptzVDF in the VRR (p <0.01). Conclusions: VRR was effective in restoring the obstruction in more than half of the patients. Furthermore, the presence of spermatozoa in the vas deferens fluid was the parameter associated with the VRR success.

Seasonal variations of male reproductive parameters of Tomodon dorsatus from Southeastern Brazil / Variações sazonais dos parâmetros reprodutivos do macho de Tomodon dorsatus do sudeste brasileiro

The morphology of the male reproductive tract of Tomodon dorsatus was described in the austral seasons of the year considering macroscopic and microscopic variables. For this purpose, 56 specimens from the herpetological collection of the "Instituto Butantan" were used. Fragments of the testes, kidneys and ductus deferens were collected and submitted to histological routine. The peak of the testicular volume was observed in the summer and the epithelium of the seminiferous tubules had higher height in the summer (p=0.001). The testes were active throughout the year, however, the spermiogenesis peaked in the summer. There were spermatozoa in the lumen of the ductus deferens in all seasons of the year. Renal length was higher in autumn (p=0.027), and renal width did not show a significant increase (p=0.237). The diameter and epithelial height of the sexual segment of the kidney (SSK) showed hypertrophy in winter and spring, coinciding with the mating period. Based on findings of this study, we can suggest that, at the population level, the reproductive cycle of T. dorsatus can be considered seasonal semi-synchronous, due to the peak of spermiogenic activity in the hot season, and discontinuous at the individual level.(AU)

A morfologia do trato reprodutivo do macho de Tomodon dorsatus foi descrita nas estações climáticas do ano com base em variáveis macroscópicas e microscópicas. Para isto, foram usados 56 espécimes oriundos da coleção herpetológica do Instituto Butantan. Fragmentos dos testículos, rins e ductos deferentes foram coletados e submetidos à rotina histológica. O volume testicular foi maior no verão e o epitélio dos túbulos seminíferos mostrou uma maior altura no verão (p=0.001). Os testículos estavam ativos durante todo o ano, contudo, a espermiogênese foi maior no verão. Espermatozoides foram encontrados no lúmen do ducto deferente em todas as estações do ano. O comprimento renal foi maior no outono (p=0.027), e a largura renal não mostrou um aumento significativo (p=0.237). O diâmetro e a altura epitelial do segmento sexual do rim (SSR) mostrou hipertrofia nas estações inverno e primavera, coincidindo com o período reprodutivo. Com base nestes resultados, pode-se sugerir que, em nível populacional, o ciclo reprodutivo de T. dorsatus possa ser considerado semi-sincrônico sazonal, devido à atividade espermiogênica na estação quente, e descontínuo em nível individual.(AU)

Does a bilateral polypropylene mesh alter the duct deferens morphology, testicular size and testosterone levels? Experimental study in rats

Abstract Purpose To evaluate the effect of a PP mesh on duct deferens morphology, testicular size and testosterone levels. Methods Forty adult male rats were distributed into groups: 1) no surgery; 2) inguinotomy; 3) mesh placed on the duct deferens; and 4) mesh placed on the spermatic funiculus. After 90 postoperative days, the inguinal region was resected, and blood samples were collected for the measurement of serum testosterone (pg/dl). The ducts deferens were sectioned in three axial sections according to the relationship with the mesh — cranial, medial and caudal. The wall thickness and duct deferens lumen area were measured. Results The morphology of the duct deferens was preserved in all groups. The mesh placement did not alter this morphology in any of the analyzed segments. Surgery, with or without mesh placement, did not alter the morphology, wall thickness or lumen area (p>0.05). In all operated groups, serum testosterone levels were similar (p>0.05) but there was a decrease in testicle size (p<0.05). Conclusion Surgery, with or without mesh placement, did not alter the morphology of the duct deferens and, although this treatment resulted in testicular size reduction, it did not affect serum testosterone levels.

Sperm morphophysiology in different sections of the rooster reproductive tract / Morfofisiología espermática en diferentes secciones del tracto reproductivo del gallo

It is important to know the morphological changes that occur in the spermatozoa of rooster during their passage through the reproductive tract, which help to understand what they acquire their fertilization capacity. The morphophysiological changes related to the capacitation and acrosomal reaction processes in the different segments of the rooster reproductive system were analyzed. Samples were obtained from various regions of the rooster reproductive tract and dorso-ventral massage to obtain ejaculates, 25 roosters were used Rhode Island Red with proven fertility, assessments were performed with chlortetracycline and Lectin WGA-FITC to determine the morphophysiological parameters. Sperm motility increases (p<0.05) during the passage of spermatozoa from the testis until they are ejaculated. The parameters of viability and morphology also show differences (p<0.05) in the different segments of the tract. Sperm morphometry shows a spermatic contraction (p<0.05) in the cranial and medial segments of the vas deferens. The acrosomal reaction capacity evaluated with chlortetracycline (CTC) or Wheat germ agglutinin (WGA), was evident increasing the parameters (p<0.05) with the use of the perivitelline layer in the spermatozoa of the reproductive tract and of the ejaculate. Spermatozoa of the reproductive tract of the rooster demonstrate acrosomal reaction capacity without requiring a previous sperm capacitation condition. On the other hand, they do not show parameters of incapacity, which implies that they cannot be stored in any segment of the reproductive tract.

Es importante conocer los cambios morfológicos que se producen en los espermatozoides del gallo durante su paso por el tracto reproductivo y que ayudan a comprender como adquieren su capacidad de fertilización. Se analizaron cambios morfofisiológicos relacionados con los procesos de capacitación y reacción acrosomal de los espermatozoides presentes en los diferentes segmentos del tracto reproductor del gallo. Se obtuvieron espermatozoides de diferentes regiones del tracto reproductor del gallo y de espermatozoides de eyaculado. Se usaron 25 gallos Rhode Island Red con fertilidad probada. Se realizaron evaluaciones básicas, con clortetraciclina (CTC) y lectina Wheat germ agglutinin conjugada con isotiosionato de fluoresceína (WGA-FITC) para determinar los parámetros morfofisiológicos. La motilidad del esperma aumenta (P<0,05) durante el paso de los espermatozoides desde el testículo hasta que son eyaculados. Los parámetros de viabilidad y morfología también muestran diferencias (P <0,05) en los diferentes segmentos del tracto. La morfometría mostró una contracción de los espermatozoides (P<0,05) en los segmentos craneal y medial del conducto deferente. La capacidad de reacción acrosomal evaluada con clortetraciclina CTC o WGAFITC, fue evidente al aumentar los parámetros (P<0,05) con el uso de membrana perivitelina en los espermatozoides del tracto reproductivo y del eyaculado. los espermatozoides del tracto reproductivo del gallo demuestran capacidad de reacción acrosomal sin requerir una condición previa de capacitación espermática. Por otro lado, no muestran parámetros de descapacitación espermática lo que implica que no pueden almacenar en ningún segmento del tracto reproductivo.

Portable model for vasectomy reversal training

ABSTRACT Objectives To validate an experimental non-animal model for training of vasectomy reversal. Materials and Methods The model consisted of two artificial vas deferens, made with silicon tubes, covered by a white resin, measuring 10 cm (length) and internal and external diameters of 0.5 and 1.5 mm, respectively. The holder of the ducts is made by a small box developed with polylactic acid, using a 3D print. The objective of the invention is to simulate the surgical field of vasovasostomy, when the vas deferens are isolated from other cord structures. For validation, it was verified the acquisition of microsurgical skills during its use, in a capacitation course with 5 urology residents from a Hospital of the region. Along the training sessions, it was analyzed the time (speed) of microsurgical sutures, and quantification of the performance using a checklist. Collected data were analyzed using de BioEstat®5.4 software. Results Medium time for the completion of microsurgical sutures improved considerably during the course, and reached a plateau after the third day of training (p=0.0365). In relation to the checklist, it was verified that during capacitation, there was significant improvement of the scores of each participant, that reached a plateau after the fourth day of training with the model (p=0.0035). Conclusion The developed model was able to allow the students that attended the course to gain skills in microsurgery, being considered appropriate for training vasectomy reversal.

Vasitis: a clinical confusion diagnosis with inguinal hernia

Abstract Vasitis or inflammation of the vas deferens is a rarely described condition categorized as either generally asymptomatic vasitis nodosa or the acutely painful infectious vasitis. Vasitis nodosa, the commonly described inflammation of the vas deferens, is benign and usually associated with a history of vasectomy. Clinically, patients present with a nodular mass and are often asymptomatic and require no specific treatment.

Crossover transseptal vasovasostomy: alternative for very selected cases of iatrogenic injury to vas deferens

ABSTRACT Inguinal herniorraphy is a possible cause of iatrogenic seminal tract obstruction. Diagnosing and correcting these vasal injuries can be challenging. Successful re-anastomosis is technically challenging, with relatively low success rates. An uncommon alternative for selected cases is the crossover transseptal vasovasostomy. We herein report a case of a 36-year-old male patient with vas deferens injury after herniorraphy and a contralateral hypotrophic testis. He was successfully treated through microsurgical crossover transseptal vasovasostomy, with spontaneous pregnancy achieved, and the technique is presented in details.

Imposex in Stramonita haemastoma from coastal sites of Cartagena, Colombia / Imposex em Stramonita haemastoma em locais costeiros de Cartagena, Colômbia

Abstract Imposex is the development of male sexual characteristics caused by the toxic effects of some chemicals that acts as an endocrinal disruptor. Antifouling paints contain these chemicals. Cartagena lacks studies to indicate the extent of imposex in its coastal waters. The aim of this study was to determine the prevalence of imposex in the gastropod Stramonita haemastoma in Cartagena, Colombia. Specimens were collected during 2013 from locations of high and low influence of port activity. Morphometric measurements and the frequency of the occurrence of imposex were registered. The comparison among morphometric variables showed statistically significant differences between the two sites studied. Furthermore, the females of the S. haemastoma species presented an imposex frequency of 93.1% in Birds' Island, Cartagena Bay, compared to 31.8% in La Bocana. The relative penis size index or RPLI (10.145 and 3.231) and vas deferens sequence index or VDSI (2.83 and 1.16), showed possible contamination by organotin compounds in both places.

Resumo Imposex é o desenvolvimento de características sexuais masculinas causadas por poluentes tóxicos de alguns produtos químicos que atuam como desreguladores endócrinos. Tintas anti-incrustantes são as que contêm estes produtos químicos. Cartagena carece de estudos para indicar a extensão do imposex nas suas águas costeiras. O objetivo deste estudo foi determinar a prevalência de imposex no gastrópode Stramonita haemastoma em Cartagena, Colômbia. Os espécimes foram coletados durante 2013 de locais de alta e baixa influência da atividade portuária. Foram registradas as medidas morfométricas e a frequência da ocorrência do imposex. A comparação entre as variáveis morfométricas mostrou diferenças estatisticamente significantes entre os dois locais estudados. Além disso, as fêmeas da espécie S. haemastomaapresentaram uma frequência de imposex de 93,1% na Ilha das Aves, Baía das Cartagena, em comparação com 31,8% em La Bocana. O índice do comprimento relativo do pênis ou RPLI (10,145 e 3,231) e o índice da sequência do vaso deferente ou VDSI (2,83 e 1,16), mostraram possível contaminação por compostos organoestânicos em ambos os locais.

Spermatozoa retrieval for cryopreservation after death

ABSTRACT Objectives To describe the retrieval spermatozoa technique for cryopreservation after death, including the proximal part of vas deferens. Material and Methods A 28-years old man, with previous history of infertility, who had died 12 hours before, was submitted to spermatozoa retrieval for cryopreservation, with surgical bilateral resection in bloc of the proximal part of vas deferens, testicle and epididymis. At the laboratory, by milking the epididymis and vas deferens, the extracted fluid was collected; also, three samples of each testicle parenchyma were also harvested. Results The fluid from the vas deferens showed spermatozoa, mostly with in situ motility. Testicular fragments also presented spermatozoa, mostly with small tail movements or immobile. Conclusion The inclusion of the proximal part of vas deferens during spermatozoa retrieval after death must be performed, since it contains high concentration of spermatozoa, and even in the presence of previous infertility, as was with this patient, it is possible to retrieve spermatozoa.

Effect of ductus deferens lavage on the time to achieve azoospermia in patients undergoing vasectomy

OBJECTIVE: To evaluate the effect of normal saline lavage of the distal vas deferens ampulla in patients undergoing vasectomy on the time to achieve azoospermia. METHODS: A prospective randomized study of 60 men divided into two groups, group lavage (GL, n=30) in which distal vas deferens ampulla lavage was performed with 10 ml of normal saline during the vasectomy, and group without lavage (GWL, n=30) in which control patients received only a vasectomy. The patients provided sperm for semen analysis at the 5th, 10th, 15th, 20th and 25th ejaculations. RESULTS: Fifteen participants in GL and 16 in GWL, for a total of 31 patients, were excluded due to not completing the control spermiogram. The tests carried out at the five ejaculations showed immobile spermatozoa in 40 and 85.71%, 66.67 and 78.57%, 93.33 and 85.71%, 86.67 and 71.43%, and 93.33 and 85.71% of participants in GL and GWL, respectively. CONCLUSION: Vas deferens duct lavage with 10 ml of normal saline during vasectomy did not decrease the time required to achieve postoperative azoospermia.

Unilateral absence of vas deferens: prevalence among 23, 013 men seeking vasectomy

ABSTRACT Purpose: To determine the prevalence of unilateral absence of vas deferens (UAVD) in men with both testes seeking vasectomy. Materials and Methods: Computerized charts of 23,013 patients encountered between January 1994 and December 2013 in one university hospital and two community clinics of Quebec City, Canada, were searched. Pre-vasectomy consultation, operative reports and semen analysis results were reviewed to identify cases of UAVD. Cases were categorized as confirmed (unilateral vasectomy and success confirmed by semen analysis) or possible congenital UAVD further sub-categorized according to whether or not a scrotal anomaly was present. Results: Among 159 men identified as potentially having UAVD, chart review revealed that 47 had only one testicle, 26 had bilateral vasa, and four were misdiagnosed (post-vasectomy semen analysis [PVSA] showing motile sperm after unilateral vasectomy) leaving 82 men deemed cases of UAVD (0.36%, 95% confidence interval 0.28% to 0.43%). These were classified as confirmed (n=48, 0.21%) and possible (n=34, 0.15%; 22 without and 12 with scrotal anomalies) congenital UAVD. The misdiagnosis ratio of UAVD was low when scrotal content was otherwise normal (1:48), but higher if anomalies were present (3:12). Conclusions: Most surgeons who perform vasectomy will encounter cases of UAVD. In most suspected cases, it is safe and effective to proceed with unilateral vasectomy under local anesthesia while stressing the need for PVSA. Further studies or scrotal exploration may be considered in patient with prior scrotal surgery.

A rare variation of the testicular blood supply by the deferential artery / Rara variación del suministro de sangre testicular por la arteria del conducto deferente

Any compression of testicular arteries may lead to loss of spermatogenesis and gonadal hormone production, existence of the variational arteries is accountable in cases of vasoligation, orchidopexy and other surgical approach on them. Anomalies of the testicular blood arteries were observed during dissection of the pelvic cavity in a 68-year-old male cadaver. This report describes a very rare case of lack of testicular arteries. For the blood supply to the testis, thick deferential arteries form some vascular winding and loops and course accompanied by deferent duct to the testis. This case report would serve as ray of light for knowledge of the possible variations of the testicular arteries during surgical procedures.

Cualquier compresión de las arterias testiculares puede conducir a la pérdida de la espermatogénesis y la producción de hormonas gonadales. La existencia de variaciones en las arterias testiculares es relevante en los casos de vasectomía, orquidopexia y otros tipos de abordaje quirúrgico. Se observaron anomalías de las arterias testiculares durante la disección de la cavidad pélvica de un cadáver de sexo masculino de 68 años de edad. En este trabajo se describe un caso muy poco frecuente de ausencia de arterias testiculares. Para el suministro sanguíneo del testículo, se encontraron arterias deferentes gruesas que producen sinuosidad y tortuosidad vascular junto al conducto deferente en los testículos. Este caso podría ser útil para el conocimiento de las posibles variaciones de las arterias testiculares durante los procedimientos quirúrgicos.

An inexpensive yet realistic model for teaching vasectomy

Purpose Teaching the no-scalpel vasectomy is important, since vasectomy is a safe, simple, and cost-effective method of contraception. This minimally invasive vasectomy technique involves delivering the vas through the skin with specialized tools. This technique is associated with fewer complications than the traditional incisional vasectomy (1). One of the most challenging steps is the delivery of the vas through a small puncture in the scrotal skin, and there is a need for a realistic and inexpensive scrotal model for beginning learners to practice this step. Materials and Methods After careful observation using several scrotal models while teaching residents and senior trainees, we developed a simplified scrotal model that uses only three components–bicycle inner tube, latex tubing, and a Penrose drain. Results This model is remarkably realistic and allows learners to practice a challenging step in the no-scalpel vasectomy. The low cost and simple construction of the model allows wide dissemination of training in this important technique. Conclusions We propose a simple, inexpensive model that will enable learners to master the hand movements involved in delivering the vas through the skin while mitigating the risks of learning on patients. .

Effects of traction on the spermatic cord of rats

PURPOSE: To determine whether tension in the spermatic cord of rats causes lesions in the testis, epididymis or vas deferens. METHODS: Forty Wistar rats were randomly allocated into four groups. A traction force of 1.6 Newton (N) in group I and 1 N in group II was applied to the right spermatic cord. Group III was the sham, and group IV served as the control. RESULTS: Testicular lesions occurred on the right side in 66.7% of the rats and on the left side in 46.1% of the rats. The testes showed a decreased number of Sertoli cells, necrosis and a decreased number of germ cells in the seminiferous tubules. Anatomopathological changes in the vas deferens were not identified. There was no decrease in the thickness of the muscle wall of the vas deferens. In the right epididymis, 71.8% of the animals showed a reduction and 5% showed an absence of intraluminal sperm. In the left epididymis, 37.5% of the rats showed a reduction. The volume and the final testicular weight of the right side in group IV was different from those in the other groups. CONCLUSIONS: Anatomopathological lesions were found in the testis and epididymis. .

Sperm analysis of the vas deferens fluid after a long interval of unilateral percutaneous epididymal sperm aspiration in vasectomized patients

Objectives Evaluation of the presence of spermatozoa in vas deferens fluid after a long interval of unilateral and homolateral percutaneous epididymal sperm aspiration (PESA) in vasectomized men. When found, the spermatozoa were evaluated including concentration and motility, in order to verify the patency of the epididymal tubules. Materials and Methods Four patients, numbered in a progressive order, from one to four, with 38, 40, 48 and 51 years old and vasectomy interval of 10, 10, 25 and 11 years, respectively, whose wives did not get pregnant using intracytoplasmic sperm injection of sperm obtained by unilateral PESA and decided to try only natural conception, were submitted to intrasurgical sperm analysis of the vas deferens fluid (ISAVDF) during microsurgery for reconstruction of the seminal tract. Results Time interval between PESA and ISAVDF was 13.75 ± 11.12 months (x ± s) varying from 3 to 29 months. Homolateral ISAVDF and PESA showed the presence of spermatozoa. Patients 1, 2 and 4 had a high concentration of 10 x 106, 64 x 106 and 45 x 106 spermatozoa/ mL; the first two had motile sperms and patient 3 had no sperms. Conclusions Three of four patients showed spermatozoa in the vas deferens fluid after a long interval of unilateral and homolateral PESA with high concentration, including motile forms. These findings support the concept that PESA may not result in late epipidymal tubule obstruction in vasectomized patients. .

Rat vas deferens SERCA2 is modulated by Ca2+/calmodulin protein kinase II-mediated phosphorylation

Ca2+ pumps are important players in smooth muscle contraction. Nevertheless, little information is available about these pumps in the vas deferens. We have determined which subtype of sarco(endo)plasmic reticulum Ca2+-ATPase isoform (SERCA) is expressed in rat vas deferens (RVD) and its modulation by calmodulin (CaM)-dependent mechanisms. The thapsigargin-sensitive Ca2+-ATPase from a membrane fraction containing the highest SERCA levels in the RVD homogenate has the same molecular mass (∼115 kDa) as that of SERCA2 from the rat cerebellum. It has a very high affinity for Ca2+ (Ca0.5 = 780 nM) and a low sensitivity to vanadate (IC50 = 41 µM). These facts indicate that SERCA2 is present in the RVD. Immunoblotting for CaM and Ca2+/calmodulin-dependent protein kinase II (CaMKII) showed the expression of these two regulatory proteins. Ca2+ and CaM increased serine-phosphorylated residues of the 115-kDa protein, indicating the involvement of CaMKII in the regulatory phosphorylation of SERCA2. Phosphorylation is accompanied by an 8-fold increase of thapsigargin-sensitive Ca2+ accumulation in the lumen of vesicles derived from these membranes. These data establish that SERCA2 in the RVD is modulated by Ca2+ and CaM, possibly via CaMKII, in a process that results in stimulation of Ca2+ pumping activity.

Obstructive azoospermia: reconstructive techniques and results

Obstructive azoospermia is a common cause of male infertility and can result from infection, congenital anomalies, or iatrogenic injury. Microsurgical vasal reconstruction is a suitable treatment for many cases of obstructive azoospermia, although some couples will require sperm retrieval paired with in-vitro fertilization. The various causes of obstructive azoospermia and recommended treatments will be examined. Microsurgical vasovasostomy and vasoepididymostomy will be discussed in detail. The postoperative patency and pregnancy rates for surgical reconstruction of obstructive azoospermia and the impact of etiology, obstructive interval, sperm granuloma, age, and previous reconstruction on patency and pregnancy will be reviewed.

A microestrutura e o desenvolvimento dos órgãos genitais masculinos de preás (Galea spixii) criados em cativeiro / The microstructure and development of male genital organs of Spix's yellow-toothed cavy (Galea spixii) bred in captivity

O preá do semiárido nordestino (Galea spixii) é um roedor pertencente à família Caviidae. São encontrados nas regiões da Caatinga e do Cerrado Brasileiro e se reproduz ao longo do ano, apresentando um período de gestação de 48 dias e uma ninhada de 2 a 4 crias. O objetivo deste estudo foi caracterizar histologicamente os componentes estruturais dos órgãos genitais de preás machos relacionando com a evolução cronológica destes órgãos na espécie. Foram utilizados para análise animais ao nascimento e aos 15, 30, 45, 60, 75, 90, 105, 120 e aos 150 dias de idade. Fragmentos do epidídimo, ducto deferente, pênis e glândulas sexuais acessórias foram coletados, fixados e processados para descrição em microscopia de luz. O epidídimo apresentou epitélio colunar simples e em cada fase sexual notou-se diferença quanto ao tamanho do lúmen tubular e à presença de espermatozóides no lúmen aos 45 dias de idade. O epitélio do ducto deferente no preá mostrou-se pseudo-estratificado colunar com crescente presença de estereocilios com o avanço da idade. A glândula vesicular no preá apresentou uma mucosa com pregueamento variado, de acordo com a fase do desenvolvimento sexual. A próstata mostrou-se pouco desenvolvida, com lúmen pequeno nos preás ao nascimento e aos 15 dias de idade; aos 45 dias mostrou-se com um pregueamento do epitélio variável. Os órgãos genitais masculinos do preá passaram por transformações morfológicas no decorrer da idade e com o desenvolvimento sexual, isso colaborou para a determinação do início da fase da puberdade, que na espécie em estudo foi aos 45 dias de idade.(AU)

The Spix's yellow-toothed cavy (Galea spixii) from the Brazilian northeastern semi-arid is a rodent that does belong to the family Caviidae. They are found in regions of the Caatinga and Cerrado, and reproduces throughout the year, with a gestation period of 48 days and a litter of 2 to 4 pups. The aim of this study was to characterize histologically the structural components of the genital organs of male Spix's yellow-toothed cavies regarding their chronological development. For the analysis we used animals at birth and with 15, 30, 45, 60, 75, 90, 105, 120 and 150 days of age. Fragments of the epididymis, vas deferens, penis and accessory sex glands were collected, fixed and processed for light microscopic. The epididymis had a simple columnar epithelium and at each sexual stage the epididymis was noted different in size of the tubular lumen and regarding the presence of sperm in the lumen at 45 days of age. The epithelium of vas deferens was found to be pseudo-stratified columnar with increasing presence of stereocilia with advancing age. The vesicular gland showed a folded mucosa that varied according to stage of sexual development. The prostate was not very developed, with a small lumen in Spix's yellow-toothed cavy at birth and at 15 days of age; at 45 days showed variable wrinkling of the epithelium. The male genital organs underwent morphological transformations in line with age and sexual development, what helped to determine the onset of puberty, which in the species studied occurred at 45 days of age.(AU)