Projections of upper structure to the spinal cardioacceleratory center in cats: an HRP study using a new microinjection method.
We studied, with the horseradish peroxidase (HRP) method, the supraspinal structure projections to the cardioacceleratory center in the intermediolateral nucleus (ILN) of T3-4 segments of the cat spinal cord. A fiber-filled double-barrel coaxial electrode was devised. The inner barrel electrode, filled with 3 M NaCl solution, was used for stimulating intraspinal structures to determine the cardioacceleratory center. The outer barrel electrode with an Agar stop, filled with a 20% HRP solution, was used for injecting HRP by pulses of positive electric current. In every experiment, HRP was injected into 3 points within the cardioacceleratory center at intervals of 1 mm. Out of 36 experiments, 10 showed that the HRP injection sites were centered in and almost confined to the ILN, and the population of the HRP-labeled cells was not less than 50. Some 1146 HRP-labeled cells were thus identified. They were distributed in the medulla oblongata (72.1%), pons (10.2%), midbrain (8.5%) and hypothalamus (9.2%). They were concentrated in the medullary reticular formation (37.8%), median raphe (26.9%) and pontine reticular formation (10.2%). Contrary to expectation, the HRP-labeled cells were few in the nucleus tractus solitarii (3.7%), paraventricular hypothalamic area (3.3%) and nucleus locus coeruleus (none).
D000818:Animals; D001339:Autonomic Fibers, Preganglionic / Q000033:anatomy & histology; D002415:Cats; D004292:Dominance, Cerebral / Q000502:physiology; D004525:Efferent Pathways / Q000033:anatomy & histology; D005260:Female; D006321:Heart / Q000294:innervation*; D006339:Heart Rate; D006735:Horseradish Peroxidase; D007031:Hypothalamus / Q000033:anatomy & histology; D008297:Male; D008526:Medulla Oblongata / Q000033:anatomy & histology; D008636:Mesencephalon / Q000033:anatomy & histology; D009474:Neurons / Q000648:ultrastructure; D011149:Pons / Q000033:anatomy & histology; D011903:Raphe Nuclei / Q000033:anatomy & histology; D012154:Reticular Formation / Q000033:anatomy & histology; D013116:Spinal Cord / Q000033:anatomy & histology*; D013564:Sympathetic Nervous System / Q000033:anatomy & histology*
D006735:Horseradish Peroxidase