A case of congenital unilateral absence of the vas deferens

Bi Mo,1 Vishnu Garla,2 Lawrence M Wyner1 1Department of Surgery, 2Department of Internal Medicine, Marshall University, Huntington, WV, USA Background: Congenital unilateral absence of the vas deferens occurs in 0.5%–1.0% of males. It has been associated with various genitourinary abnormalities, including renal agenesis. We report a case of congenital unilateral absence of the vas deferens found incidentally during vasectomy in a patient with known unilateral renal agenesis. Case presentation: A 24-year-old male presented to our urology clinic requesting vasectomy. His past history was significant for left renal agenesis. Following successful right vasectomy, several attempts to locate the left vas deferens were unsuccessful. We diagnosed congenital unilateral absence of the vas deferens. Follow-up semen analysis showed azoospermia. Conclusion: As vasectomies are increasingly performed in outpatient settings, it is imperative that physicians be aware of this condition, which can be recognized by a simple physical exam. Recognition could prevent unnecessary surgery and prompt providers to investigate for associated abnormalities. Keywords: vas deferens, embryology, abnormalities, surger

Tiger sharks can connect equatorial habitats and fisheries across the Atlantic Ocean basin.

Increasing our knowledge about the spatial ecology of apex predators and their interactions with diverse habitats and fisheries is necessary for understanding the trophic mechanisms that underlie several aspects of marine ecosystem dynamics and for guiding informed management policies. A preliminary assessment of tiger shark (Galeocerdo cuvier) population structure off the oceanic insular system of Fernando de Noronha (FEN) and the large-scale movements performed by this species in the equatorial Atlantic Ocean was conducted using longline and handline fishing gear and satellite telemetry. A total of 25 sharks measuring 175-372 cm in total length (TL) were sampled. Most sharks were likely immature females ranging between 200 and 260 cm TL, with few individuals < 200 cm TL being caught. This contrasts greatly with the tiger shark size-distribution previously reported for coastal waters off the Brazilian mainland, where most individuals measured < 200 cm TL. Also, the movements of 8 individuals measuring 202-310 cm TL were assessed with satellite transmitters for a combined total of 757 days (mean = 94.6 days∙shark-1; SD = 65.6). These sharks exhibited a considerable variability in their horizontal movements, with three sharks showing a mostly resident behavior around FEN during the extent of the respective tracks, two sharks traveling west to the South American continent, and two sharks moving mostly along the middle of the oceanic basin, one of which ending up in the northern hemisphere. Moreover, one shark traveled east to the African continent, where it was eventually caught by fishers from Ivory Coast in less than 474 days at liberty. The present results suggest that young tiger sharks measuring < 200 cm TL make little use of insular oceanic habitats from the western South Atlantic Ocean, which agrees with a previously-hypothesized ontogenetic habitat shift from coastal to oceanic habitats experienced by juveniles of this species in this region. In addition, this study adds evidence that tiger sharks are able to connect marine trophic webs from the neritic provinces of the eastern and western margins of the Atlantic Ocean across the equatorial basin and that they may experience mortality induced by remote fisheries. All this information is extremely relevant for understanding the energetic balance of marine ecosystems as much as the exposure of this species to fishing pressure in this yet poorly-known region

Tiger shark size composition.

<p>Total length-frequency distribution histogram of tiger sharks caught off the Fernando de Noronha Archipelago with longline and handline gear, in 30-cm size classes. The light grey and dark grey correspond to sharks caught with handline and longline gear, respectively.</p

Distribution of satellite transmission time.

<p>Variation of the time at which satellite transmissions were performed along the track of tiger shark #22. The vertical dashed line depicts the first transmission from land in Abidjan, Ivory Coast, which occurred in 16 November 2015.</p

Tiger shark satellite tracks.

<p>Map depicting the most-probable horizontal movements performed by eight tiger sharks tagged with pop-up satellite archival tags (PSAT; sharks #16, #17, #18 and #19) and smart position and temperature transmitting tags (SPOT; sharks #22, #23, #25 and #26) in the equatorial Atlantic Ocean. The horizontal line represents the equator. The inset map depicts location estimates of the SPOT tag deployed in shark #22. This tag stopped providing location estimates off Liberia on 23 February 2015 but it suddenly resumed satellite transmissions on 16 November 2015, when it was located on land in Adibjan, Ivory Coast.</p

Tiger shark displacement through time.

<p>Linear distance to the tagging site of tiger sharks tagged with SPOT tags between 30 July and 2 August 2014 off the Fernando de Noronha Archipelago across the extent of their respective tracks. Red line: shark #22; yellow line: shark #23; brown line: shark #25; orange line: shark #26.</p

Distribution of the number of satellite transmissions.

<p>Variation of the total number of satellite-uplinked messages per week along the track of tiger shark #22. The vertical dashed line depicts the first transmission from land in Abidjan, Ivory Coast, which occurred in 16 November 2015.</p

Study area.

<p>Geographical location of the Fernando de Noronha Archipelago in the western South Atlantic Ocean depicted by the star in the inset panel, and the map of the archipelago depicting the distribution of longline deployments in 2011 and 2012. Black circles correspond to sites where at least one tiger shark was captured, whereas white circles correspond to sites where no tiger shark was captured.</p