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Pediatric Neurology Part III

Chapter 137. Main steps of skeletal muscle development in the human: Morphological analysis and ultrastructural characteristics of developing human muscle

By: Norma Beatriz Romero,Monica Mezmezian,Anna Fidziańska

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Pediatric Neurology Part III

Chapter 137. Main steps of skeletal muscle development in the human: Morphological analysis and ultrastructural characteristics of developing human muscle

By: Norma Beatriz Romero,Monica Mezmezian,Anna Fidziańska

During embryogenesis, paraxial mesoderm undergoes segmentation into somites, progressing from head to tail. Somites differentiate into dermomyotomes, then into dermatomes and myotomes. Some head muscles derive from the anterior paraxial and precordal mesoderm. Between 10 and 13 weeks of gestation, the fusion of myoblasts generates primary myotubes with central nuclei, and the latter form the second generation of myotubes which requires active innervation. Nicotinamide adenine dinucleotide dehydrogenase-tetrazolium reductase appears before succinate dehydrogenase, and ATPase shows an intermediary activity. β-Sarcoglycan appears by 7 gestational weeks and α-sarcoglycan by 10–12 weeks. β-Spectrin, dystrophin, and utrophin appear by 9 weeks, vimentin and desmin appear by 10 weeks and stain strongly between 10 and 15 weeks. Slow, embryonic myosin heavy chain (MHC) isoenzymes appear before 15 weeks, whereas fetal fast MCH occur later (15–18 weeks). Myotubes become myofibers with peripheral nuclei between 15 and 18 weeks. Large muscle fibers (Wohlfart B) are visible by 20–21 weeks, Wohlfart A by 21–25 weeks. Perimysium surrounds compacted and grouped fibers by 24 weeks, and utrophin disappears, whereas dystrophin stains intensely. At 29 weeks, type I fibers are visible, and by 31–33 weeks they are mature for ATPase staining. Three types of type II fibers can be seen. Vimentin disappears between 15 and 30 weeks, while desmin remains weakly positive at birth.

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Page Count

36

Publisher

Elsevier Inc. Chapters

Published Date

ISBN 10

0128084030

ISBN 13

9780128084038

Pura vida

Beginning Spanish

By: Norma Lopez-Burton,Marques Pascual,Pardo Ballester

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Pura vida

Beginning Spanish

By: Norma Lopez-Burton,Marques Pascual,Pardo Ballester

In Pura vida (Life is good)Spanish is more than vocabulary and grammar, just as Spanish-speaking cultures are more than products and practices. In this learner-centered introductory program, the authors’ commitment to a methodology based on true-to-life experiences brings Spanish to life. Pura vida is the discovery of a Spanish-speaking world through the experiences of real people who share anecdotes and reflections on those experiences. Students relate to these people and make deeper, more meaningful connections between language and culture, and acquire Spanish with an unparalleled sense of personal engagement. In this 12-chapter introductory program, students don’t only learn Spanish for real life, but also from real life. They discover that there is not just one homogeneous Hispanic culture, but rather that each Spanish-speaking country has its own rich, unique culture and that the people who live in these countries speak one common language with different accents, characteristics, and idiosyncrasies. The program offers truly seamless integration of cultural notions and language instruction and features 100% contextualized and personalized activities.

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Page Count

594

Publisher

John Wiley & Sons

Published Date

ISBN 10

111949334X

ISBN 13

9781119493341