In medicine,<unk>  () refers to the failure of an organ to develop during embryonic growth and development due to the absence of primordial tissue. Many forms of<unk>  are referred to by individual names, depending on the organ affected:<unk>  of the corpus callosum - failure of the Corpus callosum to develop *Renal<unk>  - failure of one or both of the kidneys to develop *Amelia - failure of the arms or legs to develop *Penile<unk>  - failure of penis to develop *Müllerian<unk>  - failure of the uterus and part of the vagina to develop<unk>  of the gallbladder - failure of the Gallbladder to develop. A person may not realize they have this condition unless they undergo surgery or medical imaging, since the gallbladder is neither externally visible nor essential. __TOC__
Agenesis
Aplasia
Hypoplasia
Atrophy
Variegation 
Trisomy
Caudal duplication
Metaplasia