Motility

The ability to move spontaneously, used particularly with reference to independent cell locomotion (e.g., by spermatozoa) and the first movements of the embryo.  The latter are generated by spontaneous activity in the central nervous system and are not related to a specific task or goal. See Cell locomotion, Central pattern generator (CPG), Embryo, Movement, Peristaltic, …

Mosaicism

Evident in Down’s syndrome in which there is a mixture of cells containing 46 and 47 chromosomes.  Other examples of mosaicism include Edward’s syndrome and Turner’s syndrome.  It can arise as a consequence of spontaneous DNA mutations, chromosomal abnormalities, and epigenetic changes in chromosomal DNA.  The term itself denotes the presence of two or more …

Morula

A stage in the development of the embryo prior to the blastula in which a cluster of complex cells form from the solid mass of blastomere cells after the zygote splits or cleaves, resulting in 12-15 cells and looking like a mulberry (hence its name; see figure below).  Human embryos implant at this stage in …

Morphogenesis

A dynamical process involving growth and differentiation through which form and pattern are generated in biological systems.  More specifically, it describes the process of cellular differentiation, distribution and growth that takes place during the embryonic development of an organism, which gives rise to tissues, organs and anatomy.  The term morphogenesis is also used to describe …

Morpheme

In short, they are units of meaning, and consist of stem and affix morphemes.  Affixes are either derivational or inflectional.  The word ‘unlocked’ contains three morphemes ‘un-lock-ed’.  The verb ‘lock’ is the stem morpheme: ‘un’ is a derivational morpheme that changes its meaning (‘unlock’ is the opposite of ‘lock’), and ‘ed’ is the inflection telling …

Morality

Judgments, emotions, and actions pertaining to ethical decisions about right and wrong or good and bad in social relationships and beyond.  Typically, morality is expressed as a moral code (a system of morality derived from a particular culture, philosophy, religion and the like).  In this respect, there are two codes.  One is the Golden Rule …