| chorionic villus sampling | <procedure> A procedure for obtaining a sample of chorionic villi for the purpose of genetic testing, usually performed between 9 and 12th weeks of pregnancy. Amniocentesis testing has greatly supplanted the use of this form of genetic testing. (27 Sep 1997) |
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| chorionic villus biopsy | Transcervical or transabdominal sampling of the chorionic villi for genetic analysis. (05 Mar 2000) |
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| chorionic villi sampling | A method for diagnosis of foetal diseases by sampling the cells of the placental chorionic villi for DNA analysis, presence of bacteria, concentration of metabolites, etc. The advantage over amniocentesis is that the procedure can be carried out in the first trimester. (12 Dec 1998) |
| anchoring villus | A chorionic villus that is attached to the decidua basalis. (05 Mar 2000) |
| villus | Origin: L, shaggy hair, a tuft of hair. 1. <anatomy> One of the minute papillary processes on certain vascular membranes; a villosity; as, villi cover the lining of the small intestines of many animals and serve to increase the absorbing surface. 2. <botany> Fine hairs on plants, resembling the pile of velvet. Source: Websters Dictionary (01 Mar 1998) |
| primary villus | The first stage of chorionic villus development, with columns of cytotrophoblastic cells covered by syncytiotrophoblast. (05 Mar 2000) |
| secondary villus | An intermediate stage of chorionic villus development following invasion by a connective tissue core. (05 Mar 2000) |
| tertiary villus | The definitive chorionic villus with a vascular core separated from maternal blood by connective tissue, cytotrophoblast, and syncytiotrophoblast. (05 Mar 2000) |
| floating villus | A chorionic villus that is not attached to the decidua basalis, but is "free" in the maternal blood of the intervillous spaces. Synonym: floating villus. (05 Mar 2000) |
| free villus | A chorionic villus that is not attached to the decidua basalis, but is "free" in the maternal blood of the intervillous spaces. Synonym: floating villus. (05 Mar 2000) |
| biological sampling | Denotes sampling that can be taken without jeopardy to the whole organism (e.g., for haematological or biochemical study). Because of the complexity of biological samples it is usually supposed that the source of the sample is thoroughly mixed and hence representative; this assumption is often not true e.g., in genetic studies in mosaic patients. (05 Mar 2000) |
| random sampling | A selection of elements by a formal randomizing device for purposes of inference about a population of inference from that population in such a way that the probability of each possible outcome may be precisely specified in advance; the inferences are necessarily stochastic. (05 Mar 2000) |
| percutaneous umbilical blood sampling | See: PUBS. (12 Dec 1998) |
| chemical sampling | A sample that is obtained by whatever means is convenient and then purified of irrelevant elements before analysis; the assumption of thorough mixing is not necessary. (05 Mar 2000) |
| petrosal sinus sampling | Sampling of blood levels of the adrenocorticotropic hormone (acth) by withdrawal of blood from the inferior petrosal sinus. The inferior petrosal sinus arises from the cavernous sinus and runs to the internal jugular vein. Sampling of blood at this level is a valuable tool in the differential diagnosis of cushing disease, cushing syndrome, and other adrenocortical diseases. (12 Dec 1998) |
| haphazard sampling | The assembly of data in an unprescribed and undefined fashion that allows no sound scientific inferences other than establishing the existence of types. (Finding even one unicorn in such a set would establish that unicorns can exist, but no inference about their prevalence could be made from it.) Cf.: random sample. (05 Mar 2000) |