| primitive pit | The depression in the primitive node that serves to connect the notochordal canal with the surface ectoderm and the yolk sac. These connections are referred to as the neurenteric canal. (05 Mar 2000) |
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| primitive reticular cell | A cell with processes making contact with those of other similar cell's to form a cellular network; along with the network of reticular fibres, the reticular cell's form the stroma of bone marrow and lymphatic tissues. (05 Mar 2000) |
| primitive ridge | One of the paired ridge's on either side of the primitive groove. (05 Mar 2000) |
| primitive streak | An ectodermal ridge in the midline at the caudal end of the embryonic disk from which arises the intraembryonic mesoderm; achieved by inward and then lateral migration of cells; in human embryos, it appears on day 15 and gives a cephalocaudal axis to the developing embryo. Synonym: germinal streak. (05 Mar 2000) |
| neuroectodermal tumour, primitive | A malignant brain tumour sharing common features and biologic properties with medulloblastoma. Some pathologists and clinicians use the terms interchangeably: they both can disseminate throughout the nervous system and, in some cases, systemically. most lesions arise from the posterior fossa in children under five years of age. The tumour often produces hydrocephalus and symptoms of increased intracranial pressure. Papilledema is often present. (12 Dec 1998) |
| aditus pelvis | The upper opening of the true pelvis, bounded anteriorly by the pubic symphysis and the pubic crest on either side, laterally by the iliopectineal lines, and posteriorly by the promontory of the sacrum. Synonym: apertura pelvis superior, aditus pelvis, first parallel pelvic plane, pelvic brim, pelvic inlet, pelvic plane of inlet, plane of inlet. (05 Mar 2000) |
| android pelvis | A masculine or funnel-shaped pelvis. (05 Mar 2000) |
| anthropoid pelvis | An apelike pelvis, with a long anteroposterior diameter and a narrow transverse diameter. (05 Mar 2000) |
| apertura pelvis inferior | The lower opening of the true pelvis, bounded anteriorly by the pubic arch, laterally by the rami of the ischium and the sacrotuberous ligament on either side, and posteriorly by these ligaments and the tip of the coccyx. Synonym: apertura pelvis inferior, apertura pelvis minoris, fourth parallel pelvic plane, pelvic outlet, pelvic plane of outlet, plane of outlet. (05 Mar 2000) |
| apertura pelvis minoris | The lower opening of the true pelvis, bounded anteriorly by the pubic arch, laterally by the rami of the ischium and the sacrotuberous ligament on either side, and posteriorly by these ligaments and the tip of the coccyx. Synonym: apertura pelvis inferior, apertura pelvis minoris, fourth parallel pelvic plane, pelvic outlet, pelvic plane of outlet, plane of outlet. (05 Mar 2000) |
| apertura pelvis superior | The upper opening of the true pelvis, bounded anteriorly by the pubic symphysis and the pubic crest on either side, laterally by the iliopectineal lines, and posteriorly by the promontory of the sacrum. Synonym: apertura pelvis superior, aditus pelvis, first parallel pelvic plane, pelvic brim, pelvic inlet, pelvic plane of inlet, plane of inlet. (05 Mar 2000) |
| arcus tendineus fasciae pelvis | A linear thickening of the superior fascia of the pelvic diaphragm extending posteriorly from the body of the pubis alongside the bladder (and vagina in the female) and giving attachment to the supporting ligaments of the pelvic viscera. Synonym: arcus tendineus fasciae pelvis. (05 Mar 2000) |
| assimilation pelvis | A deformity in which the transverse processes of the last lumbar vertebra are fused with the sacrum, or the last sacral with the first coccygeal body. (05 Mar 2000) |
| axis pelvis | A hypothetical curved line joining the centre point of each of the four planes of the pelvis, marking the centre of the pelvic cavity at every level. Synonym: axis pelvis, plane of pelvic canal. (05 Mar 2000) |
| beaked pelvis | A pelvic deformity in osteomalacia; the pressure of the trunk on the sacrum and lateral pressure of the femoral heads produce a pelvic aperture that is three-cornered or has the shape of a heart or cloverleaf, while the pubic bone becomes beak-shaped. Synonym: beaked pelvis, rostrate pelvis. (05 Mar 2000) |