Maria Isabel Vaz de Melo

Análise qualitativa do estabelecimento da espermatogênese em cutias (Dasyprocta aguti) criadas em cativeiros

A determinacao do estabelecimento da puberdade e bastante estudada em animais domesticos e roedores, no entanto, sao escassas as pesquisas com a finalidade de estabelecer parâmetros para a biologia reprodutiva em cutias. Foram utilizadas 31 cutias machos da especie Dasyprocta agouti, oriundas da Universidade Federal do Piaui, Estado do Piaui, e da Escola Superior de Agricultura de Mossoro, Estado do Rio Grande do Norte. Imediatamente apos a orquiectomia foram retirados fragmentos e estes foram processados histologicamente, os tecidos foram corados com hematoxilina-eosina e analisou-se os parâmetros seguintes: aspectos de luminacao dos tubulos seminiferos; presenca de espermatocitos primarios; presenca de espermatides e formacao dos primeiros estagios do ciclo do epitelio seminifero (CES) segundo o metodo da morfologia tubular. O periodo desde o nascimento ate os cinco meses de idade correspondeu a fase impubere; dos seis aos oito meses de idade a fase de transicao da pre-puberdade a puberdade; dos nove aos dez meses de idade a fase da puberdade; e dos doze aos quartoze meses de idade a fase da pos-puberdade. A puberdade da cutia (Dasyprocta aguti), ocorreu em animais a partir dos sete meses de idade, e o estabelecimento da puberdade foi constatado em todos os animais estudados aos nove meses de idade.

Quantificação de células dos túbulos seminíferos e rendimento da espermatogênese em cutias (Dasyprocta aguti) criadas em cativeiros

O presente estudo teve como objetivo avaliar o rendimento da espermatogenese de cutias criadas em cativeiro, por intermedio das razoes encontradas entre tipos celulares do epitelio seminifero. Os resultados apontaram que o rendimento da espermatogenese da cutia dos nove aos quatorze meses de idade nao chegou a um ponto de estabilizacao. O coeficiente de eficiencia de mitoses espermatogoniais nao aumentou com a idade. O rendimento meiotico, o rendimento geral da espermatogenese e o indice de celulas de Sertoli mostraram variacoes numericas em funcao da idade, entretanto, nao detectadas estatisticamente.

Fases do desenvolvimento e diferenciação testicular em cutias (Dasyprocta aguti) criadas em cativeiros

A cutia (Dasyprocta aguti) e um roedor silvestre encontrado amplamente na regiao Nordeste do Brasil. E uma especie muito utilizada pela populacao humana de baixa renda como fonte alternativa de proteina na alimentacao. Foram utilizadas 31 cutias, machos, provenientes da Universidade Federal do Piaui, Estado do Piaui e da Escola Superior de Agricultura de Mossoro Estado do Rio Grande do Norte. Os animais foram divididos em grupos etarios desde o nascimento ate os 14 meses de idade. O diâmetro nuclear medio foi obtido pela medida de 10 nucleos do tipo celular estudado em cada testiculo, no estagio 1 do ciclo do epitelio seminifero. Nos animais que nao apresentaram o epitelio organizado em estagios bem definidos em virtude da idade, foram feitas medidas em seccoes transversais escolhidas somente pelo contorno circular. O inicio da assincronia do processo espermatogenico foi observado a partir dos seis meses de idade. A puberdade, na cutia Dasyprocta aguti, foi definitivamente estabelecida a partir dos nove meses de idade, pois estavam presentes todos os tipos celulares e espermatozoides liberados no lume tubular em grande parte do parenquima testicular.

Efeito de diferentes diluidores sobre a viabilidade espermática pós-descongelação de sêmen eqüino

The effect of different egg yolk, sugars and buffering systems concentrations in the freezability of differents equine semen extenders was studied. Extenders were: D1=10% of egg yolk added of more 50% over the lactose and glicose-EDTA levels found in D5; D2=10% of egg yolk and reduction of 50% over the lactose and glucose-EDTA levels in D5; D3=20% of egg yolk added of more 50% over the lactose and glucose-EDTA levels in D5; D4=20% of egg yolk and reduction of 50% over the lactose and glucose-EDTA levels in D5; D5=20% of egg yolk and lactose and glucose-EDTA according to Martin et al. (1979). Five ejaculates of six stallions were used to test extenders using alternatively two differents cryoprotectants agents: 3.5% ethylene glycol and 5% acetamide. After the final dilution, the semen was submitted to differents freezing rates. Straws were thawed at 75o C during 7 seconds, followed by immersion at 37oC during 5 seconds. After thawing motility, vigour, structural and functional integrity of the membrane of the spermatozoa were evaluated. The reduction in the egg yolk concentration from 20% to 10%, in extenders with the same concentration of sugars and buffering systems, did not modify the crioprotectant capacity of the extender with ethylene glycol or acetamide. The increase in the concentration of sugars and buffering systems in the lactose-EDTA-egg yolk extender did not add crioprotectant effect to ethylene glycol and acetamide. Extenders with high osmolarity had tended to better preserve the frozen equine semen with ethylene glycol or acetamide. Better results of spermatic viability, after thawing, were obtained when semen was diluted in D1, D3 and D5 extender (P<0.05).

Aspectos biométricos do desenvolvimento testicular e corporal em cutias (Dasyprocta aguti) criadas em cativeiros

Analisou-se os dados biometricos do desenvolvimento testicular e peso corporal de 31 cutias (Dasyprocta aguti) desde o nascimento ate os 14 meses de idade. As correlacoes entre o peso corporal, idade e parâmetros testiculares apresentaram-se altamente significativas. O peso testicular, o volume testicular, assim como os demais parâmetros biometricos testiculares (comprimento, diâmetro e perimetro), evoluiram lenta e gradualmente ate os 8 meses de idade. A partir dos 9 meses, o crescimento foi mais rapido. O desenvolvimento biometrico do testiculo pode ser dividido em duas fases, de 0 - 8 meses e de 9 - 14 meses de idade, sendo 9 meses considerado ponto de corte em se tratando de desenvolvimento testicular de cutias criadas em cativeiro.

Análise histométrica do desenvolvimento testicular de cutias (Dasyprocta aguti) criadas em cativeiros

Foi estudado, por meio da histometria, o desenvolvimento testicular em 31 cutias da especie Dasyprocta aguti desde o nascimento ate 14 meses de idade. O diâmetro e a area, medios, foram obtidos a partir de 30 seccoes transversais de cordoes e/ou tubulos seminiferos, em cada testiculo, utilizando-se sistema de computadorizado de analises de imagem e uma ocular micrometrica Zeiss CPL 10X, acoplada a uma objetiva de 40X. As proporcoes volumetricas do testiculo foram obtidas com o metodo estereometrico, segundo Elias, Henning e Schwartz1. O diâmetro tubular medio apresentou crescimento lento desde o nascimento ate os oito meses de idade, nas duas metodologias empregadas. Quando foi usada a ocular micrometrica observou-se que, a partir de nove meses, o diâmetro tubular teve um crescimento acelerado, chegando a duplicar o seu valor, se comparado com grupo etario que o antecedia. A proporcao volumetrica dos cordoes testiculares e tubulos seminiferos cresceu gradualmente, atingindo, aos nove meses, seu valor maximo (86,50%). As celulas de Leydig apresentaram proporcao volumetrica decrescente, e seus maiores valores foram expressivos do nascimento ate quatro meses de idade (7,00 ± 1,77% a 9,55 ± 0,64%) e minimos a partir de nove meses, tendendo ainda a uma estabilizacao. O estroma diminuiu com a evolucao da idade caindo bruscamente a partir da puberdade. Conclui-se que o diâmetro dos cordoes testiculares e tubulos seminiferos apresentou maior crescimento, coincidindo com o inicio da puberdade e a proporcao volumetrica das celulas de Leydig encontrou-se, respectivamente, mais alta e mais baixa no mesmo periodo.

Sex ratio of equine offspring is affected by the ages of the mare and stallion.

The aim of this study was to determine the influence of parental age on the sex ratio of offspring in horses. Two trials were performed. In the first trial, the data from a randomly obtained population with a 1:1 sex ratio of 59,950 Mangalarga Marchador horses born in Brazil from 1990 to 2011 were analyzed. The sex ratios of the offspring were compared among groups according to the mare and the stallion ages (from 3 to 25 years). In the first step of the analysis, the mares and stallions were grouped according to age in 5-year intervals. In the second step, the groups were based on the parental age gap at conception. In the third step, the group of the mares and stallions with similar ages from the second step was subdivided, and the different parental age subgroups that were divided into 5-year intervals were compared. In the fourth step, the sex ratio of the offspring was determined according to the ages of the mares and the stallions at conception. The second trial was based on the data from 253 horses of several breeds that were born after natural gestation into a herd from 1989 to 2010, and the offspring of groups that were younger or older than 15 years were compared. The data from both trials were analyzed using a chi-square test (P ≤ 0.01 for the first trial; and P ≤ 0.05 for the second trial) for the comparisons of the sex ratios. In the first trial, the Spearman test (P ≤ 0.01) was used to verify the correlations between the parental age and the offspring sex ratio. In the first trial, the offspring sex ratio decreased as the mare or stallion age increased, and the decrease was more marked for the mares than for the stallions. In the second trial, the mares older than 15 years had more fillies than the younger mares, but the stallion age had no effect on the sex of the offspring. The first trial, with a large number of horses, revealed the pattern of the distribution of the sex ratios of offspring according to the parental age in horses, whereas the second trial, with a more restricted number of horses, confirmed the influence of the age of the mare on the offspring sex ratio. We concluded that the parental age affected the offspring sex ratio in horses and that this effect was stronger for the mares than for the stallions.

Low Density Lipoproteins at 2% Concentration Can Replace Whole Egg Yolk in TES-Tris-Milk Extender for Freezing Buffalo Sperm Cells

Background: Over the years, the most commonly used extenders for semen cryopreservation contain egg yolk as cryoprotectant. However, more recent studies have used the low density lipoproteins, extract of hen egg yolk which is responsible for the cryoprotective effect. Nevertheless, little was known about its required minimum concentration as well as its interaction with other extra cellular cryoprotectants, like skimmed milk. The present study aimed at investigating the effect of replacing whole egg yolk by adding low density lipoproteins at low concentrations, in TES-Tris-skim milk based extender, on the post-thaw quality of buffalo bull sperm. Materials, Methods & Results: Eighteen ejaculates were collected from six buffalo bulls and diluted with TES-Tris-skim milk based extender containing LDL, extracted from hen egg yolks, at the concentrations of 2%, 4%, 8% and 14%, against a control extender containing 20% fresh egg yolk. After semen collection, analyses of subjective motility, vigor, force tourbillon, sperm concentration (Neubauer chamber) and sperm morphology (phase contrast microscopy) were performed. The diluted semen was packaged in 0.25 mL straws, and cooling was performed on computerized machine (TK 4000®), using a cooling rate of -0.25°C/min to 5°C. Semen was kept in balance at 5°C for 4 h. The straws were frozen in an ice chest, kept at 5 cm from the surface of liquid nitrogen for 20 min and then immersed in liquid nitrogen. The samples were kept in cryogenic container until thawing. Post-thaw kinetic parameters during incubation at 37°C (CASA), sperm membrane integrity (SYBR-14/PI), membrane functionality (hypo-osmotic swelling test) and DNA fragmentation (%DFI - SCSA) were evaluated after thawing. Immediately post-thaw, total motility was higher in the control (56.53 ± 9.73) than in the tested extenders; however, after 30 min the difference was no longer detected. All other kinetic parameters presented significantly better results in extenders containing 2%, 4% and 8% LDL, compared with the control. There was no difference between treatments regarding the integrity of membranes or fragmentation of the DNA after freezing/thawing procedures. Discussion: The molecules of low density lipoproteins of egg yolk have the known action of sequestering BSP ( binder of sperm proteins) protein, due to the chemical affinity of their main components, phosphatidylcholine and phosphatidylethanolamine. The BSP are responsible for removing cholesterol from the plasma membrane of the sperm, preparing it for the sperm capacitation phase. Low density lipoproteins by inhibiting the action of the BSP increase the stability of the plasma membrane during the freeze-thaw process. The milk caseins micelles have a similar ability to bind the BSP, but with lower affinity. The present study has shown that the use of purified low density lipoproteins has an advantage over the use of whole egg yolk, especially with regard to the kinetic parameters of the spermatozoa after thawing. Furthermore, it was observed that low concentrations of low density lipoproteins, such as 2%, in extenders containing skim milk, could preserve the sperm cell during the freeze-thawing process like that higher LDL concentrations and whole egg yolk. Further studies are needed to determine if the cryoprotectant action found in this study was a result of the synergistic action of skim milk with lipoproteins or even at low concentrations like 2% the lipoproteins can provide protection to the buffalo spermatozoa during freezing, as it has been reproduced in other domestic species. In conclusion, our results indicated that the extender TES-Tris-skim milk containing 2% LDL extracted from egg yolk could be used successfully in the cryopreservation of buffalo sperm cells.

Efeito da radiação vermelha de baixa intensidade sobre o sêmen canino criopreservado

The aim of this study was to analyze the effect of low intensity red light on some kinetic parameters of cryopreserved canine sperm. Ejaculates from 08 adult dogs were centrifuged, diluted in Tris-egg yolk with 6% glycerol, and subsequently separated into: T1: incidence of red light (660 nm) (Fisioled -MMOptics - 100mW) for 60 seconds before the cooling and after thawing, T2: just before cooling, T3: only after thawing, and T4: no incidence. After thawing the samples were subjected to TTR using Sperm analyzer(r). In TTR0, TTR60 and TTR90 there were no differences between the variables analyzed by CASA. Only in TTR30 the effects of the incidence of red light were visible and significant in T1 and T2. T1 resulted in low MT (12.5 ±10.6%) and T2 determined the best result of MT 26.1%±40.3. Similarly T1 showed a higher number of static spermatozoa (77.5±28.9%) compared to T2 (50.6±28%). We concluded that the double incidence of low intensity red light, before cooling and after thawing, had a deleterious effect on canine sperm motility expressed at 30 minutes after thawing.