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, …
Category Archives: Uncategorized
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 …
Morphology (linguistics)
In linguistics, a term that refers to the study of morphemes and other linguistic units (e.g., affixes, intonations, words), as well as also to the morphemic structure of a language (e.g., un-, happy, and -ness in unhappiness). It is thus the unit of language that is ‘one up’ from phonemes. Typically, they are considered to …
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 …
Morphological marking
The inflection of words to mark changes in meaning or grammatical function, such as the addition of ‘was’ to nouns to mark their plurality. Languages that use a relatively large number of morphological (or inflectional) markings) tend to have no fixed word order. They do so in order to disambiguate the roles of arguments. Somewhat …
Morphogenetic field
A group of cells of a particular organ whose position and fate are specified with respect to the same set of boundaries. The field has a definite boundary and the organ forms only from interactions between cells within the field. Gradients within the field can serve as a source of positional information as to where …
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 …
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 …
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 …
Moro response
The spreading (abduction) of a newborn’s arms and fingers (see figure below), followed by strong flexion (adduction) at the shoulder, after a sudden change in head or whole body position. It is assumed to be a labyrinthine reaction, but there is some debate about this as there is about whether the response is symmetrical or asymmetrical …