Play tutoring

Intervention by an adult to raise levels of pretend or sociodramatic play in pre-school children through suggestion, modeling, and provision of props and stimulation.  There have been claims that play tutoring gives rise to improvements in competence broadly defined.  However, it is possible that such improvements could be due to contact with adults due tutoring …

Play fighting (or rough-and-tumble play)

A social form of play where the participants compete for some advantage.  Even though competition is involved, the actions are attenuated to allow all participants to gain the advantage at least some of the time.  Typically, it is more an activity of boys than girls.  See Fantasy play, Fighting, Play, Sex roles, Sex-typing

Play

Although an unambiguous definition of this behavior is still in dispute, most definitions would include two criteria: an absence of an immediate utilitarian purpose and the presence of actions that are seemingly performed for their own sake (i.e., the process of the play is more important than any end point or goal). See Cognitive immaturity hypothesis, …

Placode

Local thickening in the embryonic ectodermal layer in the early embryo.  The cells of the placed ordinarily constitute a primordial group from which a sense organ (e.g., lens placode) or neurons of sensory ganglia will be derived. Other parts of these ganglia arise from the neural crest.  See Brain-derived neurotrophic factor (BDNF), Ectoderm, Ganglia, Neural …

Placenta

In mammalian species, the organ in the uterus containing blood vessels that unites the fetus and mother, providing the fetus with oxygen and nutrients from maternal circulation while also removing waste products.  Made by trophoblastic tissue and extra embryonic mesoderm.  See Amnion (or amniotic sac), Chorion, Dizygotic twins, Mesoderm, Monozygotic twins, Nicotine, Ontogenetic adaptation, Pulsatility index (PI)