ANTIGEN-INDUCED CHANGES ON HIGH ENDOTHELIAL VENULES IN RAT CERVICAL LYMPH NODES

Abstract

The effect ofantigenic stimulation(paratyphoid vaccine) on high endothelialvenules (HEVs) of rat cervical lymph nodeswas studied using conventional histologicaland histometrical techniques. The sequentialchanges of some morphometric parameters(lymph node weight, HEV diameters) after theantigenic stimulation were studied in ratcervical lymph nodes over a period offive dayswith daily measurements. Measurements weremade on the HEVs in the paracortexespecially near the corticomedullary junction.HEVs diameters began to increase two daysafter the antigenic stimulation (p<O.OOl) anderythrocytes were increased in the lumen ofthe HEVs. On day four, most of the lymphocyteswere detected between the endothelialcells of the HEVs (p<O.OOl). On day five, notonly HEVs were increased in number but alsoendothelial cells were increased in height(p<O.OOl). The weight of the lymph nodeswas also highest on this day. The changes ofHEVs determined after antigenic stimulationsuggest that these specialized vessels have animportant regulatory role in the primaryimmune response.