Thousands of microvilli form a structure called the brush border that is found on the apical surface of some epithelial cells, such as the small intestines. (Microvilli should not be confused with intestinal villi, which are made of many cells.
Autism spectrum disorder has no single known cause. Given the complexity of the disorder, and the fact that symptoms and severity vary, there are probably many causes. Both genetics and environment may play a role. 1  Genetic problems. 2  Several different genes appear to be involved in autism spectrum disorder.
Autism spectrum disorder is a serious neurodevelopmental disorder that impairs a child's ability to communicate and interact with others.It also includes restricted repetitive behaviors, interests and activities. These issues cause significant impairment in social, occupational and other areas of functioning.lthough the term Asperger's syndrome is no longer in the DSM, some people still use the term, which is generally thought to be at the mild end of autism spectrum disorder. The number of children diagnosed with autism spectrum disorder is rising.