O útero artificial / The artificial uterus

Médico, biofísico, filósofo e ex-membro do Comité Nacional de Ética para as Ciências da Vida, Henri Atlan oferece, na sua última publicação de O Útero Artificial (2005), as suas reflexões sobre os progressos da embriologia e da genética em matéria de procriação medicamente assistida. Com palavras simples, mostra como a science-fiction de ontem tornar-se-á, num futuro mais ou menos próximo, a ciência de amanhã, como as perturbações provocadas pelo aparecimento da contracepção hormonal e as fertilizações in vitro parece-nos -rem anodins- ao lado de os procedentes do desenvolvimento o ectogenese (ou útero artificial), a clonagem reprodutiva, a reprodução por estaca e o parthénogenèse. Atlan assegura que hoje as finalidades terapêuticas justificam o financiamento destas investigações: salvar grandes os prematuros ou os fetos procedentes de abortos espontâneos e não desejados por transferência num Útero Artificial. Mas, previne Henri Atlan, quando estes técnicos estiverem à ponto, pedidos extramédicos adicionar-se-á aos tratamentos terapêuticos. As mulheres poderão, e algumas quererão, dissociar procriação e gravidez. Ser mãe sem gravidez seria à alcance de mão, da mesma maneira que é-o hoje épanouissement de uma sexualidade sem criança. Estas perturbações provocarão consequências sociais, culturais, economicas, políticos, religiosos e mesmas metafísicas pouco previsíveis sobre o conjunto da sociedade. Os sexos serão por último à igualdade perante a procriação, estruturas familiares novas antes genéticas e sociais que biológicos aparecerão, o sentimento materno alterar-se-á. Só ponto de interrogação em ausência de experimentação: o que será de a criança, soncorps, os seus sentimentos e aptidões mentais sem a simbiose que oferece o gravidez? Num espírito especulativo, Henri Atlan mede estas mudanças em relação mythologie, a filosofia, a literatura e da história, navega entre o totalitarismo eugénique e o liberalismo individualista para fazer-nos tomar consciência dos desafios subjacentes à estas inovações.

Effect of Reproductive Status on In Vitro Developmental Competence of Bovine Oocytes

The objectives of the present study were to compare the in vitro maturation (IVM), fertilization and early embryonic development of bovine oocytes recovered from ovaries during the follicular, metestrus and diestrus stages of the estrous cycle and at anestrus and pregnancy after maturation in a serum free culture medium. Cumulus oocyte complexes (COCs) collected from ovaries at different reproductive statuses were matured in medium 199 supplemented with 10 g/ml FSH, 10 g/ml LH, 1.5 g/m estradiol, 75 g/ml streptomycin, 100 IU/ml penicillin and 10 mM HEPES. COCs were incubated in 200 microliter droplets of maturation medium 199 under oil for 24 h at 39degrees c and 5% CO2. Matured oocytes were exposed to frozen-thawed TALP swim up, heparin capacitated sperm from two bulls separately in each replicate (20 h, 39C, 5% CO2). After fertilization, the presumptive zygotes were cultured in medium 199 containing 8 mg/ml BSA-V, 100 IU/ml penicillin-G, 75 g/ml streptomycin and 10 mM HEPES for 144 h at 39C and 5% CO2 without medium freshening or change. Oocytes/embryos were fixed, stained with DAPI and evaluated under fluorescent microscope. The IVM rates were almost similar among oocytes from all reproductive statuses (range: 89.8 to 95.4%). However, IVM rates for oocytes from the metestrus (90.6%) and pregnant (89.9%) phases were lower than the other groups. The fertilization rates were lower (p<0.05) for oocytes from the diestrus phase (72.4%) than from the other phases (range: 81.1 to 86.6%). Oocytes, recovered during the metestrus phase of the estrous cycle, resulted in the highest cleavage rate (60.0%), while oocytes from the diestrus phase had the poorest embryonic development (39.8%: p<0.05). Majority of the embryos from all reproductive phases showed a developmental arrest around 8-cell stage. Although the developmental competence of oocytes from pregnant and anestrus animals was lower than that from the other reproductive stages, they could be potentially used as oocyte donors. Long term, in vitro embryo culture without medium freshening or change was hypothesized to have caused the failure to overcome the 8-cell block to development.

Effects of Protein Source and Energy Substrates on the In Vitro Development of Bovine Embryos in a Two-step Culture System

In this study, we examined the effects of a two-step culture system, which involves the use of different culture media for early cleavage and later stage embryos, on the in vitro development of bovine embryos. We also investigated the effect of glucose, phosphate and citrate on the in vitro early developmental period of bovine embryos in a two-step culture system. Moreover, the supplementation of different protein sources (BSA-V, BSA-FAF and FBS) during IVC did not affect the frequency of blastocyst development. Using two-step culture, embryos were cultured in protein-free media for an initial 5 days. This was then followed by the same culture media or an FBS supplemented media. The developmental rates of blastocysts in the FBS containing group were significantly higher than in the replaced with no serum containing group. Embryos cultured in mSOF supplemented with 1.5 mM glucose plus 1.2 mM phosphate were significantly inhibited. The inhibition of developmental competence by glucose plus phosphate was consistent with the existence of 0.5 mM sodium citrate. This study indicates that a two-step culture system, which applies different conditions for early cleavage embryos, i.e., serum-free media, vs. later stage embryos, with serum containing media, may be effective for in vitro production systems. In addition, the developmental competence of bovine embryos was depressed in the presence of glucose plus phosphate as compared to either alone or the absence of both. Therefore, the avoidance of this negative effect should allow more optimal conditions to be developed for in vitro production.