After injecting the posterior pituitery of the albino rats with cholera-toxinconjugated HRP,retrogradely labeled neurons were found in the area of the bednuclei of the stria terminalis (BST),which were then analyzed,based on therecent cytoarchitectonical study of the BST.In the anterior subdivision of the BSTdendrites could be seen in the parastrial nucleus with a few labeled cells surround-ing it;cells of the magnocellular nucleus were found scattered in the subdivision;some labeled cells were also identified in the ventral nucleus.Surrounding the dor-sal half of the posterior division of the BST there were several fairly distinct labe-led cell groups,viz.,the anterior fornical nucleus,medial and lateral dorsal accessorygroups,and the subinterventricular group.Though these cell groups are contiguouswith the BST,they do not seem to belong to the BST itself,but their dendritesoften extend into the posterior division of the BST,thus sharing some commonafferents with the latter.A few less constant cells were sometimes seen scattered invarious parts of the BST.

Horseradish peroxidase was injected into C_(6,7) or L_(5,6) spinal cord in 21 adult cats and the morphology and distribution of the labeled cells in the dorsal columu nuclei (DCN) were studied. Cells projecting to the cervical cord were found to be distributed mainly in a region from 2.5mm below to 0.5mm above the obex, while cells projecting to the lumbar cord were found within 2.5mm below the obex. Medio-Iaterally, the cervical projecting cells were located chiefly at the junctional area between the gracile and medial cuneate nuclei and at the ventromedial part of the latter. The lumbar projection cells were located more medially, concentrating at the junctional area and the ventrolateral part of the gracile nucleus. In both cases scattered cells were found in the two dorsal column nuclei. The difference in cellular distribution between cervical and lumbar injection cases is consistent with a somatotopical organization.The labeled cells in the dorsal column nuclei varied in shape and size. Small cells, mostly fusiform, were concentrated at the junctional area between the gracile and medial cuneate nuclei. Large cells were found scattered in the two nuclei. Many of them were triangular or multipolar with long and straight dendrites. A few were round and their dendrites bushy.

HRP was injected into the cervical or lumbar spinal cord in 8 adult cats. The anterogradely labeled terminal arborization and its relation with the retrogradely labeled cells in the DCN were studied.The non-primary afferent fibers were distributed diffusely in the DCN. Injection of HRP in one spinal segment, either cervical or lumbar, resulted in labeling of terminal branches throughout the rostrocaudal extent of the DCN. In C6 or C7 injection cases large amount of labeled terminal branches were found in the medial cuneate nucleus, chiefly in its extraclusteral regions, viz. in the rostral part and in the ventral area of the caudal two thirds of the nucleus. A small celled area at the dorsolateral brim of the middle part of the medial cuneate nucleus was found to approach and to be contiguous with the external cuneate nucleus at higher level. This area was likewise densely labeled. Labeled terminal branches were also found in the gracile nucleus in lesser amount.After L5 or L6 injections the labeled terminals were much less in amount than in cervical injection cases. They were distributed mainly in the gracile nucleus. In the lower part of the nucleus the labeled terminals were found in its dorsal, medial, and ventrar areas. In the upper part of the nucleus they projected diffusely. A slight degree of labeling was also found in the ventromedial angle of the medial cuneate nucleus.The areas of distribution of the labeled terminals and labeled cells overlapped but did not coincide with eachother. No or merely a few labeled terminals were found around some of the labeled cells, while other cells were located right in the center of heaviest terminal labeling with abundant terminal branches surrounding their somata and dendrites. This proved that the non-primary afferent fibers of the DCN might form monosynaptic feed-back loop with the DGN-spinal cells.

HRP was injected into the cervical or lumbar spinal cord in 8 cats and the spinobrainstem projections were traced with the anterograde HRP technique. The labeled terminal branches were found most densely concentrated in the ipsilateral dorsal column nuclei and lateral reticular nucleus, the contralateral medial and dorsal accessory olivary nuclei and the bilateral pontobulbar bodies and dorsolateral part of pontine nuclei. In the reticular formation and a number of brainstem nuclei labeled terminals were also found to varying degrees. The most remote site found labeled was the hypothalamus.It was also found that the dorsal accessory olivary nucleus could be further subdivided into a caudal and an oral part, cells in the caudal part being smaller than that in the oral one.In the accessory olivary nuclei labeled terminal branches were more numerous in lumbar injection cases. Clearcut somatotopical localization was demonstrated in the oral part of the dorsal accessory olivary nucleus.In the lateral reticular nucleus the subnucleus magonocellularis and the lateral wing of the subnucleus parvocellularis were the major sites of labeling and the labeling in cervical injection cases greatly out numbered that in lumbar injections.The cervical and lumbar injections were equal in their amount of projection to the pontobulbar bodies and the dorso-lateral part of the pontine nuclei.The distribution of spinal afferents in the inferior olivary nucleus, the lateral reticular nucleus, the pontobulbar body and the pontine nucleus was discussed.

Different parts of the cochlea were destroyed in 6 cats (11 sides). The degenerating fibers and preterminal degenerations were studied by the Nauta technique with the following conclusions: 1. The overwhelming majority of the fibers from the spiral ganglion project to within the limit of the cochlear nucleus complex. No fiber degeneration could be found in the trapezoid body. A few degenerating fibers from the basal turn of the spiral ganglion, however, were found in the dorsal acoustic stria. 2. No preteriminal degeneration was found in the “granular cell masses” and “dorsal cell complex of the acoustic tubercle”of G. Fuse. 3. In the dorsal cochlear nucleus, degenerating fibers were found to terminate in the II-V layers. 4. Contrary to Lorente de No’s finding, the present study showed that the fibers from the basal portion of the spiral ganglion bifurcate at the dorsal part of the ventral cochlear nucleus, those from the apical portion at the ventral part. 5. The spiral ganglion projects in a clear-cut topographical way to the 3 parts of the cochlear nucleus complex, viz, the basal portion and the successively more apical portions of the spiral ganglion project (a) to the dorso-medial and successively more ventro-lateral parts of the dorsal cochlear nucleus; (b) to the anterior part of the ventral cochlear nucleus along the dorso-caudo-medial to ventro-rostro-lateral axis; and (c) to the posterior part of the ventral cochlear nucleus along the dorso-rostro-medial to ventro-caudo-lateral axis.

The dorsal accessory olivary nucleus was studied with electron microscope in seven rabbits.The axo-axonal synapses,an axon being in contact synaptically with a spine of a perikaryon,the glomerulus with an axonal core and a bundle of microfibers within a nucleus of a neuron,as well as the already discovered axo- dendritic synapses,axo-somatic synapses and glomeruli with dendritic cores,were observed in this nucleus. The axo-dendritic synapses were often seen,the postsynaptic components of them were dendrites or spines.The axo-somatic synapses were fewer.An axonal terminal was seen synapsing to both a spine of a perikaryon and a dendrite.Both the presynaptic and postsynaptic components of the axo-axonal synapses contained spherical vesicles.Sometimes the axo-axo-dendritic synapses were observed.There were two kinds of glomeruli in this nucleus,one with dendritic core and the other axonal core.Two axons were discovered simultaneously synapsing with an axon. The complex synaptic pattern in the dorsal accessory olivary nucleus indicated that the afferent impulses would undergo diffusing,converging,presynaptic inhibition or integrating in this nucleus.

Cytoarchitecture of the ventrolateral superficial area of the medulla was studied on normal rabbit Nissl sections.There was a superficial area of small and medium sized cells,mostly fusiform,lateral to the pyramid.In middle and upper parts of the medulla superficial cells were also found in less amount in more lateral regions. At the middle medullary level there was a band of cells about 300 ?m from the surface with medium sized ones as its most prominent elements. HRP or WGA-HRP was injected in 10 rabbits into the cervical,thoracic or lumbar spinal cord unilaterally and its connection with the ventrolateral superficial area of the medulla was traced.Labeled cells were found in all cases along the pyramid.The lateral part of the superficial area was less labeled.The medium sized cell band at the middle medulla was markedly labeled,especially in thoracic injec- tion cases.More labeled cells were found in cervical injection cases in an area ventromedial to the facial nucleus. Anterogradely labeled terminal arborizations were in general small in amount, somewhat more prominent in cervical cases. The relation between the ventrolateral superficial area and the chemosensitive area is disscussed.

A glucose oxidase-3,3′ diaminobenzidine-nickel method was developed.Thistechnique can successfully demonstrate the details of the immunoreactive structuresand PHA-L labeled cell bodies and their processes.It is especially beneficial forvisualizing fibers and terminals.It is more sensitive than the regular 3,3′ diamino-benzidine method and the glucose oxidase-3,3′ diaminobenzidine technique,andvery stabilized.

The oval nucleus of the bed nuclei of the stria terminalis of the rats was found in a previous investigation be studded with the corticotropin releasing factor (CRF) and neurotensin (NT)-immunoreactive(ir) neurons. The present work was to study their distribution and the possible coexistence of these two neuropeptides in the neuron of oval nucleus. The CRF- and NT- ir neurons were demonstrated to be densely and evenly distributed in the nucleus, among which were scattered a substantial number of cells cocontaining CRF and NT.

Based upon Ju and Swanson's studies on the eytoarchitecture of the bed nuclei of stria terminalis (BST) of the rat, the present work studies in detail the distribution of serotonin-immunoreactive fibers and terminals (5-HT-ir fibers) in the BST of the rat with ABC or PAP technique visualized with glucose oxidase-DAB-nickel method. The results are as followsithree types of 5-HT-ir fibers were identified in the BST, viz. thick fibers, thin fibers and varicose fibers. Only varicose fibers were found in the stria extension of the BST, whereas the rest of the BST contained other types as well. In the oval nucleus, juxitacapsular nucleus, fusiform nucleus, posterior dorsal nucleus and principle nucleus,all three types of 5-HT-ir fibers were observed, while the remaining parts of the BST were occupied with thin and varicose fibers. These fibers were distributed unevenly in the BST, with highest density in the ventromedial part of the anterior ventral area and the ventrolateral part of the posterior division; moderate density in the anterior dorsal area, the ventrolateral part of the anterior ventral area and the dorsolateral part of the posterior division; and were scattered in the anterior lateral area and the medial part of the posterior division. The difference in density of 5-HT-ir fibers among various areas of the BST corresponds generally with the sequence of ontogenesis of the BST. Mismatch of the distribution of 5-HT-ir fibers and 5-HT receptors in the BST of the rat is also discussed.