No definition
Category Archives: Uncategorized
Rhotic sound
A class of speech sounds produced with an r-like quality such as the vowel in the word ‘bird’ or the first sound in the word ‘ray’. See Bilabial, Fricative, Glottal, Labio-dental, Lateral sound, Lingua-alveolar (or alveolar), Lingua-palatal (or palatal)
Rhombic lip
See Cerebellum (development)
Revised Class Play
A peer assessment technique in children‚was report on the behavior and reputations of others in their classroom. This assessment consistently yields three broad dimensions of social reputation amongst children: 1. Sociable-Leader, 2. Aggressive-Disruptive, and 3. Sensitive-Isolated. See Pupil Evaluation Inventory, Sociometry
Rhombencephalon
See Diencephalon, Mesencephalon, Metencephalon, Prosencephalon
Rett’s syndrome
A progressive neurogenetic disorder with onset in the first few years of life, and for which the first sign is usually hypotonia (a loss of muscle tone). Characterized by stunted development, a lag in brain and head growth, loss of purposeful hand use and a number of major neurological problems, including epilepsy and decreased mobility …
Reverse genetics
The process of searching for phenotypes through altering specific gene functions. The experimental procedure involved begins with a cloned segment of DNA, or a protein sequence, and using this knowledge to introduce programmed mutations (through directed mutagenesis) back into the genome in order to investigate gene and protein function . See Conditional knockouts, Forward genetics, …
Retrovirus
A class of enveloped viruses (e.g., HIV) that have their genetic material in the form of RNA. They infiltrate RNA and establish a template for foreign DNA to be established in the host, a process known as reverse transcription or transcriptase involving RNA ‚aa DNA information transfer. Can result in the production of abnormal protein …
Retinoic acid (RA)
There are cytoplasmic retinoic acid binding proteins and retinoic acid response elements that regulate gene transcription. Retinoic acid, a product of vitamin A, is thought to be a morphogen in limb bud development that probably accounts for its potent teratogenic action . See Appendicular muscles, Cones and rods, Polarizer, Teratogen, Vitamin A
Retinopathy of prematurity
Previously termed retrolental fibroplasia, it consists of damage to the blood vessels of the retina, which may become detached if the resulting scar tissue contracts. Linked to hyperpoxia, resulting from an overly high level of oxygen therapy, it can lead to blindness in very preterm and very low birthweight infants. Previously thought to have been …