Heterochrony—variation in the rate or timing of developmental processes or events over evolutionary time—plays an important role in the study of evolutionary developmental biology. I review the historical background of heterochrony, and highlight examples of how both physical structure and behavior are influenced by changes in the rate of development. I also describe neurogenetic models of evol...

Developmental dyscalculia (DD) is a learning disorder affecting the acquisition of school level arithmetic skills present in approximately 3-6% of the population. At the behavioral level DD is characterized by poor retrieval of arithmetic facts from memory, the use of immature calculation procedures and counting strategies, and the atypical representation and processing of numerical magnitude. ...

Sea Urchin is one of the most useful tools in developmental biology studies because this organism has the simplest kind of developmental stages. We aimed to determine developmental stages and timetable of Echinometra mathaei embryo (the species of Persian Gulf). The spawning of E. mathaei was induced by 0.5M KCl injection (1ml) into the coelomic cavity. After fertilization, embryos were placed ...

The Necessity of Paying Attention to the Developmental and Educational Significance of Pre-School Years, as Indicated by Contemporary Research E. Talaa'ee, Ph.D. H. Bozorg To demonstrate the necessity of paying attention to the developmental and educational significance of the early years of childhood (from birth to first grade) by all involved, a subset of all related researc...

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