Duration of the cycle of the seminiferous epithelium and daily sperm production of Brazilian hairy rams

Cardoso, F.M.; Queiroz, G.F.

doi:10.1016/0378-4320(88)90047-4

Cited by 24 publications

(12 citation statements)

References 14 publications

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“…Similar changes occurred at corresponding times in previous studies that involved increased testicular temperatures in bulls and rams (Howarth 1969;Meyerhoeffer et al 1985;Saab et al 2011;Rocha et al 2015;Hamilton et al 2016) with some apparent differences in the magnitude of changes and the interval from the thermal insult to recovery, attributed to the degree and duration of testicular heating and perhaps species-specific characteristics (Skinner and Louw 1966;Rathore 1970;Brito et al 2004;Nichi et al 2006). Furthermore, in this study, sperm damage occurred during the final stages of spermatogenic development in the testis (Howarth 1969;Cardoso and Queiroz 1988;Senger 2003). Although sperm at various stages of development or in the epididymis may be affected by increased testicular temperature (Lue et al 1999;Perez-Crespo et al 2008;Hamilton et al 2016), in our study, due to the delay from testicular heating to appearance of abnormalities, there was no apparent effect on sperm present in the epididymis.…”

Section: Discussionsupporting

confidence: 64%

Hyperthermia and not hypoxia may reduce sperm motility and morphology following testicular hyperthermia

Kastelic¹,

Wilde²,

Rizzoto³

et al. 2017

Vet. Med.

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ABSTRACT:The mammalian testis typically operates on the brink of hypoxia; the long-standing dogma is that increased testicular temperature increases metabolism, but blood flow is unaffected and the resulting hypoxia reduces sperm motility and morphology. In rats and mice, oxygen (O 2 ) content of inspired air affected O 2 content of testes, enabling the latter to range from approximately 50 to more than 200% of physiologic concentrations. A ram model was used to test the hypotheses that hypoxia would disrupt sperm motility and morphology and that hyperoxia would prevent hyperthermia-induced reductions in sperm motility and morphology. Eighteen Canadian Arcott rams (approximately 10 months old) were used in a 2 × 3 factorial, with factors being scrotal insulation (insulated or not insulated) and O 2 concentrations in inspired air (14, 21 or 85%). Six rams, three with and three without scrotal insulation, were placed in each of three enclosed areas for 30 h to expose them to their respective oxygen concentrations, with scrotal insulation removed at the end of the exposure. Semen was collected by electro-ejaculation twice before insulation, bi-weekly for four weeks starting one week after exposures, and then once weekly for two weeks. There were effects of insulation, time and an insulation × time interaction for motile sperm and sperm that had normal morphology or head or midpiece defects (P < 0.01 for each). Sperm motility and morphology exhibited alterations between approximately two and five weeks after insulation, with mean progressively motile and morphologically normal sperm decreasing from approximately 55 to 35% and from 80 to 30%, respectively, and with head and midpiece defects increasing from approximately 3 to 50% and from 10 to 20% (P < 0.05 for each). The hypotheses that hypoxia would disrupt sperm quality and production, whereas hyperoxia would prevent hyperthermia-induced reductions in sperm quality and production, were not supported. This is apparently the first report that heat-stress induced damage to sperm was due to increased temperature per se and not testicular hypoxia, calling into question a long-standing paradigm.

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Section: Discussionsupporting

confidence: 64%

Hyperthermia and not hypoxia may reduce sperm motility and morphology following testicular hyperthermia

Kastelic¹,

Wilde²,

Rizzoto³

et al. 2017

Vet. Med.

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“…As spermatogenesis proceeds via an orderly series of events, estimation of the approximate stage of germ cell development at various intervals before the time that sperm becomes available for ejaculation was possible. Based on the description of the ovine seminiferous epithelium cycle -approximately 61 days (MALAMA et al, 2013), these periods are consistent with the influence of heat on epididymis maturation (P1), seminiferous tubules (later and earlier spermiogenesis = P2; meiotic divisions = P3; mitotic phases of spermatogonia or spermatocytogenesis = P4), and recovery of the normal semen production period (P5) in treated rams (CARDOSO;QUEIROZ, 1988;JOHNSON et al, 2000;MALAMA et al, 2013).…”

Section: Experimental Designsupporting

confidence: 69%

Microscopic sperm head damage and abnormalities as heat stress indicators in Australian Merino rams <i>(Ovis aries)</i> in Northern Patagonia, Argentina

Armengol

Sabino

Bérgamo

et al. 2018

Braz. J. Vet. Res. Anim. Sci.

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Na Patagônia Norte, os ovinos têm sua estação de acasalamento iniciada em 15 de março, portanto, ficam sujeitos às temperaturas do verão. A exposição de carneiros a estresse térmico aumenta a prevalência de danos microscópicos e anomalias morfológicas nos espermatozoides, que implica uma redução na fertilidade. Este trabalho avaliou a capacidade adaptativa de carneiros Merino Australiano com lã (N = 6) e tosquiados (N = 6): metade ficou ao ar livre e outra metade foi mantida em uma câmara climática por oito horas, durante cinco dias, chegando gradualmente a uma temperatura máxima de 40 °C. Foram analisados danos microscópicos, anormalidades e alterações ultramicroscópicas da membrana plasmática e do acrossoma da cabeça dos espermatozoides. Os resultados microscópicos confirmaram a existência de diferença significativa na porcentagem de espermatozoides sem cauda e com gota citoplasmática proximal, entre os ejaculados pós-tratamento. A temperatura afetou os carneiros tosquiados, principalmente a cabeça de seus espermatozoides, durante a espermatogênese. Alterações submicroscópicas foram observados na membrana plasmática quando ela estava presente no segmento anterior: quando não intacta, ficava ondulada ou dilatada. Quando a membrana plasmática estava ausente, o acrossoma podia se apresentar ondulado ou dilatado. Além disso, sob efeito do calor, a membrana acrossomal externa pode perder completamente seu conteúdo ou apresentar núcleo desnudo. A membrana plasmática assume uma forma ondulada pelo efeito da temperatura no epidídimo. Depois de dez semanas, a cabeça dos espermatozoides recuperou sua forma normal. Como demonstrado neste estudo, a cabeça sem cauda, as gotas citoplasmáticas proximais e as categorias ultramicroscópicas estudadas são indicadores do efeito do estresse térmico no sêmen, e os carneiros com maior cobertura de lã se adaptam melhor ao estresse por calor. Alterações de microscopia e de microscopia eletrônica de transmissão têm se mostrado excelentes indicadores de estresse por calor em carneiros Merino Australiano e podem ser ferramentas úteis para ajudar criadores de ovelhas a escolher quando começar a época de acasalamento, o que irá variar de acordo com as condições ambientais do verão.

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“…The circle indicates the most advanced labeled germ cells at 1 hour, 11 days, and 22 days after BrdU injection, suggesting that each spermatogenic cycle in ovine testis grafts lasts approximately 11 days. The square indicates the stage where the labeled germ cells would be located according to the literature (Ortavant, 1956; Cardoso and Queiroz, 1988). SPG‐A indicates type A spermatogonia; SPG‐B, type B spermatogonia; SPG‐In, intermediate spermatogonia; Pl, preleptotene spermatocytes; L, leptotene; Z, zygotene; P, pachytene; D, diplotene; II, secondary spermatocytes; R, round spermatids; and E, elongate spermatids.…”

Section: Resultsmentioning

confidence: 99%

“…In pigs, each spermatogenic cycle lasts 8.6–9.0 days, and the total duration of spermatogenesis is around 40 days (Swierstra, 1968; Franca and Cardoso, 1998). In sheep, the length of the spermatogenic cycle and the total duration of spermatogenesis are 10.6 and 47–48 days, respectively (Ortavant, 1956; Cardoso and Queiroz, 1988).…”

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confidence: 99%

The Length of the Spermatogenic Cycle Is Conserved in Porcine and Ovine Testis Xenografts

Avelar

Rathi

França

et al. 2006

Journal of Andrology

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Xenografting of immature mammalian testis tissue into mice can accelerate sperm production. To determine whether this shortened time to sperm production is because of reduced length of the spermatogenic cycle, we applied bromodeoxyuridine (BrdU) incorporation to analyze the spermatogenic cycle in porcine and ovine testis xenografts. Small testis fragments from newborn pigs and sheep were ectopically grafted into mice. Once complete spermatogenesis was present in grafted tissue, mice were injected with BrdU and grafts were recovered at different time points thereafter. In porcine grafts, the most advanced germ cells labeled 1 hour, 9 days, 12.3 days, and 18 days after BrdU injection were stage 1 preleptotene/leptotene primary spermatocytes, stage 1 pachytene primary spermatocytes, stage 5 newly-formed round spermatids, and late stage 2 elongating spermatids, respectively. In ovine grafts, the most advanced labeled germ cells at 1 hour, 11 days, and 22 days post-BrdU injection were stage 2 preleptotene/ leptotene primary spermatocytes, late stage 1 pachytene primary spermatocytes, and stage 2 elongating spermatids, respectively. These results indicate that each spermatogenic cycle in porcine and ovine xenografts lasts approximately 9 and 11 days, respectively, which is similar to their durations in situ. Therefore, the length of the spermatogenic cycle is conserved in porcine and ovine testis xenografts. This is consistent with earlier reports showing that the cycle length is inherent to the germ cell genotype. The shortened time to sperm production in xenografts therefore appears attributable to accelerated maturation of the testicular somatic compartments. Our results suggest that testis xenografts provide a useful model to study the timing of testicular maturation and spermatogenesis in different mammalian species.

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Duration of the cycle of the seminiferous epithelium and daily sperm production of Brazilian hairy rams

Cited by 24 publications

References 14 publications

Hyperthermia and not hypoxia may reduce sperm motility and morphology following testicular hyperthermia

Hyperthermia and not hypoxia may reduce sperm motility and morphology following testicular hyperthermia

Microscopic sperm head damage and abnormalities as heat stress indicators in Australian Merino rams <i>(Ovis aries)</i> in Northern Patagonia, Argentina

The Length of the Spermatogenic Cycle Is Conserved in Porcine and Ovine Testis Xenografts

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