Search results for "sperma"
showing 10 items of 296 documents
Análisis prospectivo de selección inmunomagnética en espermatozoides para la mejora de los resultados de las técnicas de reproducción asistida
2017
Introducción La infertilidad afecta a una de cada 5 parejas con la intención de concebir solucionado en parte por el desarrollo de las distintas técnicas de reproducción asistida (TRAs), aunque a pesar de los logros alcanzados, todavía existe un elevado porcentaje de casos en los que estas técnicas no son 100% efectivas o son necesarios repetidos intentos para lograr una gestación. La responsabilidad del éxito reproductivo está compartida entre el gameto masculino y el femenino. Los gametos femeninos son el factor limitante en cualquier técnica de reproducción, ya que se generan muy pocos, cuesta mucho de obtenerlos y todos ellos se utilizan, por lo que en principio no va a ser posible sele…
Vidolicīna totālā sintēze
2015
Vidolicīna totālā sintēze. Kazak M., zinātniskie vadītāji: Dr. chem. prof. E. Sūna E; Dr. chem. K. Shubin. Maģistra darbs, 53 lappuses, 43 attēli, 1 tabula, 55 literatūras avoti. Latviešu valodā. Maģistra darbs ir veltīts Aspidosperma alkaloīdu grupas pārstāvja vidolicīna stereoselektīvajai totālajai sintēzei. Totālās sintēzes atslēgas stadijas ir augsti diastereoselektīva N-terc-butilsulfinilimīna aldola-tipa reakcija un allijodīda secīga fotoķīmiska izomerizācija-ciklizācija. Svarīgāko starpsavienojumu struktūra un stereocentru absolūtā konfigurācija ir pierādīta ar KMR spetroskopijas un rentgenstaru difrakcijas metodēm.
Seminal plasma biochemistry and spermatozoa characteristics of Atlantic cod (Gadus morhua L.) of wild and cultivated origin
2011
Abstract Our objectives were to compare spermatozoa activity, morphology, and seminal plasma (SP) biochemistry between wild and cultivated Atlantic cod ( Gadus morhua ). Swimming velocities of wild cod spermatozoa were significantly faster than those of cultivated males. Wild males had a significantly larger spermatozoa head area, perimeter, and length, while cultivated males had more circular heads. Total monounsaturated fatty acids and the ratio of n−3/n−6 were significantly higher in sperm from wild males, while total n−6 from cultivated males was significantly higher than the wild males. Significantly higher concentrations of the fatty acids C14:0, C16:1n−7, C18:4n−3, C20:1n−11, C20:1n−…
1599 Peri- and Postoperative Complications of 215 Cases of Inguinal Hernia in Children
2012
Background The cure of inguinal hernia in children consists of high ligation of hernial sac, generally evolving with few complications. Aim The evaluation of casuistry structure and evaluation of peri- and postoperative complications in children. Method Retrospective analytical study for a period of three years includes case studies which required high ligation of the hernia sac (procesus vaginalis). Results The 214 cases were stratified according to: Location: left side 29 hernias (13.5%); bilateral 4 (1.8%); right side 181 (84.5%) cases; Age: 1–3 years, 70 (32.7%); 4–6 years, 71 (33.1%); 7–12 years, 62 (28.9%); 13–18 years, 11 cases (5.1%); During hospitalization: ≤ 3 days, 65 (30.3%); 4–…
Disrupting immune regulation incurs transient costs in male reproductive function.
2014
9 pages; International audience; BACKGROUND: Immune protection against pathogenic organisms has been shown to incur costs. Previous studies investigating the cost of immunity have mostly focused on the metabolic requirements of immune maintenance and activation. In addition to these metabolic costs, the immune system can induce damage to the host if the immune response is mis-targeted or over-expressed. Given its non-specific nature, an over-expressed inflammatory response is often associated with substantial damage for the host. Here, we investigated the cost of an over-expressed inflammatory response in the reproductive function of male mice. METHODOLOGY/PRINCIPAL FINDINGS: We experimenta…
Multiple sex-chromosome system and other karyological characterizations of Pterotrachea hippocampus (Mollusca: Mesogastropoda)
1993
Two modal diploid numbers of chromosomes were found for Pterotraches hippocampus Philippi (Mollusca: Mesogastropoda) collected from the Gulf of Palermo in 1990: 2n=31 and 32 for males and females, respectively. This, along with other karyological characteristics such as the occurrence of a trivalent configuration at diakinesis and two types of metaphase-II spreads in spermatocytes, supports the notion that a X1X2Y♂/X1X1X2X2♀ sex mechanism operates in the species investigated here. Silver nitrate procedure revealed an intraindividual variation in the Ag-staining pattern occurring in this species. The majority of the chromosome pair displayed terminal and/or interstitial heterochromatic block…
Scanning electron microscopy of heterochromatin in chromosome spreads of male germ cells in Schistocerca gregaria (Acrididae, Orthoptera) after tryps…
1996
Chromosome spreads, prepared from testes of the desert locust Schistocerca gregaria, were analyzed using scanning electron microscopy (SEM) after varying periods of preincubation in trypsin. The emphasis of the study was on the appearance of heterochromatin. A trypsin pretreatment of 5 sec resulted in a smooth surface on the chromatin throughout and the heterochromatin was highly electron-emissive. The facultatively heterochromatic X chromosome was clearly visible in interphase spermatogonia and in pachytene and late prophase I spermatocytes. Chromomeres of autosomal bivalents could be recognized in pachytene cells. Centromeric heterochromatin segments were very prominent in autosomes of la…
Male Investments in High Quality Sperm Improve Fertilization Success, but May Have Negative Impact on Offspring Fitness in Whitefish.
2015
Many ejaculate traits show remarkable variation in relation to male social status. Males in disfavoured (subordinate) mating positions often invest heavily on sperm motility but may have less available resources on traits (e.g., secondary sexual ornaments) that improve the probability of gaining matings. Although higher investments in sperm motility can increase the relative fertilization success of subordinate males, it is unclear whether status-dependent differences in sperm traits could have any consequences for offspring fitness. We tested this possibility in whitefish (Coregonus lavaretus L.) by experimentally fertilizing the eggs of 24 females with the sperm of either highly-ornamente…
Centrosome structure is very similar in eupyrene and apyrene spermatocytes ofEphestia kuehniella(Pyralidae, Lepidoptera, Insecta)
1997
Summary The higher Lepidoptera produce two types of sperm, eupyrene and apyrene. Eupyrene spermatozoa are fertile, while apyrene spermatozoa are anucleate and, therefore, sterile. Meiosis differs between the two developmental lines. One of the most obvious differences is the aberrant organization of the apyrene spindles. They possess fewer microtubules than eupyrene spindles and chromosome segregation is irregular. To determine whether micotubule nucleation is impaired in the aprene spindles, the present fine structure study concentrated on the centrosomes in both spermatocyte types. In addition, the presence of gamma-tubulin, a newly discovered tubulin isoform which is prevalent in centros…
Karyotype analysis of the sea urchinParacentrotus lividus (Echinodermata): evidence for a heteromorphic chromosome sex mechanism
1996
A consistent diploid number of 2n = 36 was determined for the sea urchinParacentrotus lividus from the Gulf of Palermo by analysis of mitotic chromosomes of both early developing embryos and male gonads. The haploid numbern = 18 was determined by counts of spermatocyte bivalents at diakinesis. A heteromorphic chromosome sex mechanism of the XY type is likely present in this species. This is indicated by the occurrence of a chromosomal pair, pair No. 2, which is heteromorphic in both morphology and size in about 50% of the mitotic figures (metaphases and anaphases) of einbryos. In addition, heteromorphism of the same pair of chromosomes occurred during spermatogonial metaphases in the five m…