| PNET | peripheral neuroepithelioma; primitive neuroectodermal tumor |
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| 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) |
| aggregated lymphatic follicles of vermiform appendix | Masses of lymphoid tissue in the submucous coat of the vermiform appendix. Synonym: folliculi lymphatici aggregati appendicis vermiformis. (05 Mar 2000) |
| appendix | <anatomy> A worm-shaped process projecting from the blind end of the caecum. (27 Sep 1997) |
| appendix ceci | A wormlike intestinal diverticulum extending from the blind end of the caecum; it varies in length and ends in a blind extremity. Synonym: appendix vermiformis, appendix ceci, processus vermiformis, vermiform appendage, vermiform process, vermix. (05 Mar 2000) |
| appendix epididymidis | A small pedunculated body often attached to the head of the epididymis which is a vestige of the embryonic mesonephric duct. Synonym: appendix epididymidis, pedunculated hydatid. (05 Mar 2000) |
| appendix epididymis | A small cystic projection from the surface of the epididymus which represents a remnant the embryologic mesonephros. (12 Dec 1998) |
| appendix epiploica | A finger-like projection of fat attached to the colon. (12 Dec 1998) |
| appendix fibrosa hepatis | A fibrous process, into which the tip of the left lobe of the liver may taper out, that passes with the left triangular ligament to be attached to the diaphragm. Synonym: appendix fibrosa hepatis. (05 Mar 2000) |
| appendix of epididymidis | A small pedunculated body often attached to the head of the epididymis which is a vestige of the embryonic mesonephric duct. Synonym: appendix epididymidis, pedunculated hydatid. (05 Mar 2000) |
| appendix of the testis | A vesicular nonpedunculated structure attached to the cephalic pole of the testis; a vestige of the cephalic end of the paramesonephric (mullerian) duct. Synonym: appendix testis, appendix of the testis, nonpedunculated hydatid, ovarium masculinum, sessile hydatid. (05 Mar 2000) |
| appendix testis | A small solid projection of tissue on the outer surface of the testis which is a remnant of the embryologic mullerian duct. (12 Dec 1998) |