A) The polar body is the egg cell which is then fertilized by the sperm cell. B) Far fewer eggs are produced by the female than sperm produced by the male. C) Meiosis I begins in the female fetus. D) Meiosis II is not completed until after the egg cell makes contact with the sperm cell.
What he was more interested in was the way in which fundamental concepts like the very idea of number, time, quantity, causality, justice and so on emerged. Piaget (1936) was the first psychologist to make a systematic study of cognitive development. His contributions include a stage theory of child cognitive development, detailed observational studies of cognition in children, and a series of simple but ingenious tests to reveal different cognitive abilities.
John B. Watson and Jean-Jacques Rousseau are typically cited as providing the foundations for modern developmental psychology. In the mid-18th century Jean Jacques Rousseau described three stages of development: infants (infancy), puer (childhood) and adolescence in Emile: Or, On Education.