Embryology is a branch of science concerned with the morphological aspects of organismal development. The genomic and molecular revolution of the second half of the 20th century, together with the classic descriptive aspects of this science have allowed greater integration in our understanding of many developmental events. Through such integration, modern embryology seeks to provide practical knowledge that can be applied to assisted reproduction, stem cell therapy, birth defects, fetal surgery and other fields. This book focuses on human embryology and aims to provide an up-to-date source of information on a variety of selected topics. The book consists of nine chapters organized into three sections, namely: 1) gametes and infertility, 2) implantation, placentation and early development, and 3) perspectives in embryology. The contents of this book should be of interest to biology and medical students, clinical embryologists, laboratory researchers, obstetricians and urologists, developmental biologists, molecular geneticists and anyone who wishes to know more about recent advances in human development.

Spermatozoa in testicular fluid are known to have weak forward motility and cannot fertilize eggs. The epididymis is known to participate in sperm maturation leading fertilization, but little is known about the specific epididymal molecules involved in the modification of sperm. In this study, we characterized the new pattern of expression of an antigen previously identified in testicular germ cells by monoclonal antibody (mAb) TRA 54. This antigen is expressed in epididymal and vas deferens epithelial cells in mice older than 24 days but not during younger developmental stages. Evaluation by immunohistochemistry shows that antigen expression is limited to the cytoplasm of a specific cell population of epithelia along the epididymal regions and vas deferens of adult mice. The molecules synthesized and released by epididymal and vas deferens epithelia into their lumen seem to bind on spermatozoa moving down through the ducts. Immunoblot analysis showed that the molecules recognized by mAb TRA 54 in testis and epididymis were similar and share a common epitope involving carbohydrate domains. Interestingly, the antigens identified in epididymal and vas deferens epithelial cells were expressed independently of testicular germ cells and are produced in an androgen-dependent manner. Finally, the molecules recognized by mAb TRA 54 seem to play an important role in spermatogenesis, as well as in epididymal function related to spermatozoa maturation and ability to fertilize.

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Oxidative stress occurs when there is an over production of free radicals and cells are not able to neutralize them by their own antioxidant mechanisms. These excess of free radicals will attack cellular macromolecules leading to cell damage, function impairment or death. Because of that, antioxidant substances have been largely used in products to offer complementary protection. In this study a new mixture of three known antioxidants (cocoa, green tea and alpha-tocopherol) was evaluated and its antioxidant protection was assessed focusing on its capacity to protect main cell macromolecules. Results have shown that it has a high antioxidant capacity by protecting lipids, DNA and proteins against oxidative damage. The antioxidant effect of the mixture on cells was also investigated and it was able to reduce oxidative stress generated by lipopolisacharide in human fibroblasts. Finally, as the mixture has proved to be highly antioxidant, its effect on cell senescence was evaluated, and it was demonstrated that fibroblasts in culture had delayed senescence when treated with these actives on a mixture. All results together provide important data about a new antioxidant mixture that uses a small amount of actives and is able to protect cell against oxidative damages in a global way.

-Central nervous system (CNS) remyelination following toxically-induced demyelination is a well known process. Oligodendrocytes constitute the bulk of the myelinating cells in the brain where a s Schwann cells overwhelm oligodendrocytes numbers in spinal cord remyelination. Despite the common knowledge of these facts, we still do not know completely the origin of both remyelinating cells. The pre sent study investigated the participation of mature oligodendrocytes in remyelination after ethidium-bromide (EB) induced demyelination in the brainstem of normal and cyclosporin A-immunosuppressed Wi s t a r rats. Thirty adult female rats were divided into three experimental groups. In group 1 the rats received a single intracisternal injection of 10 µL of 0.1% ethidium bromide (EB) in 0.9% saline (n=10); in group 2 the rats received the EB injection while immunosuppressed with cyclosporin A (n=10); in group 3 the rats received a single 10 µL injection of 0.9% saline while treated with cyclosporin A. The rats were killed at 15, 21 and 31 days after injection. Within the EB lesions, from 15 days onward many cells within the periphe ry of the lesions stained positive for OSP (oligodendrocyte specific protein) a marker for mature oligod e n d rocytes and myelin. This cell marking signals that, at least, part of the process of repairing the myelin sheaths is carried out by mature cells of the oligodendrocyte lineage.KEY WORDS: toxic demyelination, remyelination, oligodendrocytes, oligodendrocyte specific protein (OSP), ethidium bromide.Oligodendrócitos remielinizantes positivos para OSP -proteína específica do oligodendrócito-no tronco encefálico de ratos Wistar desmielinizados toxicamente RESUMO -A remielinização do sistema nervoso central após desmielinização tóxica é um processo bem conhecido. No encéfalo, os oligodendrócitos remielinizam uma área maior do que na medula espinhal, onde as células de Schwann são preponderantes. Embora esses fatos sejam bem conhecidos, ainda não se conhece com certeza a origem das células remielinizantes. Esta investigação foi desenhada para esclarecer a participação de oligodendrócitos maduros na re c o n s t rução das bainhas perdidas após a desmielinização induzida por brometo de etídio (BE) no tronco encefálico de ratos Wistar normais e imunossuprimidos com ciclosporina A. Trinta ratos fêmeas adultas foram divididos em três grupos experimentais. No g rupo 1, os ratos receberam uma injeção de 10 µL de BE em 0,9% salina (n=10) na cisterna basal; no gru p o 2, os ratos receberam a injeção de BE e foram tratados com ciclosporina A (n=10); no grupo 3 os ratos re c eberam uma injeção de 10 µL de 0,9% salina e foram tratados com ciclosporina A. Os ratos foram sacrificados aos 15, 21 e 31 dias após a injeção. A partir dos 15 dias muitas células da periferia das lesões tiveram m a rcação positiva para OSP (proteína específica do oligodendrócito), marcador de oligodendrócitos maduro s e mielina. Assim, foi possível comprovar que células maduras da linhagem oligodendroglial participam do...