THE SEGMENTAL DISTRIBUTION OF THE LABELLED SYMPATHETIC PREGANGLIONIC NEURONS AFTER HORSERADISH PEROXIDASE(HRP)INJECTION INTO THE COELIAC GANGLION OF THE CAT / 解剖学报

ABSTRACT

Twelve adult cats were used in our experiment.Under sodium pentobarbitalanesthesia one to two mg of HRP(Sigma Type Ⅵ),dissolved in 7 to 15 microlitresof distilled water,was slowly injected into the ganglion at two or three sites.Theleft coeliac ganglion was injected in seven cats,the right in other four and in oneboth sides were injected.After postoperative survival of 2～5 days,the animalswere perfused through the left ventricle with a mixture of 2% paraformaldehydeand 1.25% glutaraldehyde in 0.1 M phosphate buffer(pH 7.4).Serial frozen crosssections of the spinal cord were cut at 48 micra after postfixation and all sectionsof even numbers were selected and processed with the blue reaction according toMesulam's eighth procedure(1976)and counterstained with neutral red.The labelled cells were found in ipsilateral cord of the injected ganglion,andwere distributed in a transverse zone which may be divided into four nuclei1.thenucleus intermediolateralis pars principalis(IL_p)2.the nucleus intermediolateralispars funicularis(IL_f)3.the nucleus intercalatus(IC)and 4.the nucleus interca-latus pars paraependymalis(IC_(pe)).The total number of the labelled cells in eachcase varies from 1,179 to 92.The segmental range of the labelled cells extendedfrom the T_1 to the L_1 segments in the longest and from the T_4 to the T_(10)or fromthe T_3 to T_9 segments in the shortest.The data were treated with the statisticalweighted method,and the result showsabout 69.93%?0.57 of the total labelledcells are located in the spinal segments from T_5 to T_8,and about 21.61%?0.52 inthe T_6 segment.The percentage of labelled cells in the four nuclei given above isas followsIL_p77%,IL_f12%,IC9% and IC_(pe)2%.Furthermore the majorityof labelled cells in IC and IC_(pe)were found in T_(5～8)segments,the greatest densityof them was in the T_6 segment of spinal cord.We found no obvious difference between the left and right in the pattern of thedistribution and the segmental arrangment of the labelled sympathetic preganglionicneurons.