| primary tooth | A tooth of the first set of teeth, comprising 20 in all, that erupts between the mean ages of 6 and 28 months of life. Synonym: dens deciduus, baby tooth, deciduous dentition, dens lacteus, first dentition, milk tooth, primary dentition, primary tooth, temporary tooth. (05 Mar 2000) |
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| primary transcript | <molecular biology> RNA transcript immediately after transcription in the nucleus, before RNA splicing or polyadenylation to form the mature mRNA. (18 Nov 1997) |
| primary tuberculosis | First infection by Mycobacterium tuberculosis, typically seen in children but also occurs in adults, characterised in the lungs by the formation of a primary complex consisting of small peripheral pulmonary focus with spread to hilar or paratracheal lymph nodes; may cavitate or heal with scarring or may progress. Synonym: childhood type tuberculosis. (05 Mar 2000) |
| primary tumour | <oncology> The mass of tumour cells at the original site of the neoplastic event from the primary tumour metastasis will lead to the establishment of secondary tumours. (18 Nov 1997) |
| primary union | Healing by fibrous adhesion, without suppuration or granulation tissue formation. Synonym: primary adhesion, primary union. (05 Mar 2000) |
| primary uterine inertia | True uterine inertia, uterine inertia that occurs when the uterus fails to contract with sufficient force to effect continuous dilation or effacement of the cervix or descent or rotation of the foetal head, and when the uterus is easily indentable at the acme of contraction, secondary uterine inertia, uterine inertia that occurs when the uterine contractions are vigorous but, as a result of the exhaustion or dehydration of the patient, decrease in vigor, and the progress of labour ceases. (05 Mar 2000) |
| primary vaccination | <virology> First or principal vaccination with the introduction of a vaccine into the body for the purpose of inducing immunity. (18 Nov 1997) |
| primary villus | The first stage of chorionic villus development, with columns of cytotrophoblastic cells covered by syncytiotrophoblast. (05 Mar 2000) |
| primary visual area | Area of the occipital lobe concerned with vision. (12 Dec 1998) |
| primary visual cortex | See: visual cortex. (05 Mar 2000) |
| primary vitreous | The vitreous first formed in the embryo between the optic cup and the lens vesicle, and later vascularised by the hyaloid artery and its branches. (05 Mar 2000) |
| hyperoxaluria, primary | Either of two genetic disorders characterised by urinary excretion of large amounts of oxalate, with nephrolithiasis, nephrocalcinosis, early onset of renal failure, and often a generalised deposit of calcium oxalate, resulting from a defect in glyoxalate metabolism. (12 Dec 1998) |
| neoplasms, multiple primary | Two or more abnormal growths of tissue occurring simultaneously. The neoplasms are histologically different and may be found in the same or different sites. (12 Dec 1998) |
| neoplasms, second primary | Abnormal growths of tissue that follow a previous neoplasm but are not metastases of the latter. The second neoplasm may have the same or different histological type and can occur in the same or different organs as the previous neoplasm but in all cases arises from an independent oncogenic event. The development of the second neoplasm may or may not be related to the treatment for the previous neoplasm since genetic risk or predisposing factors may actually be the cause. (12 Dec 1998) |
| neoplasms, unknown primary | Metastases in which the tissue of origin is unknown. (12 Dec 1998) |