Our confocal three-dimensional analyses revealed substantial differences in the innervation to vibrissal follicle-sinus complexes (FSCs) in the rat and cat. This is the first study using anti-protein gene product 9.5 (PGP9.5) immunolabeling and confocal microscopy on thick sections to examine systematically the terminal arborizations of the various FSC endings and to compare them between two species, the rat and the cat, that have similar-appearing FSCs but different exploratory behaviors, such as existence or absence of whisking. At least eight distinct endings were clearly discriminated three dimensionally in this study: 1) Merkel endings at the rete ridge collar, 2) circumferentially oriented lanceolate endings, 3) Merkel endings at the level of the ring sinus, 4) longitudinally oriented lanceolate endings, 5) club-like ringwulst endings, 6) reticular endings, 7) spiny endings, and 8) encapsulated endings. Of particular contrast, each nerve fiber that innervates Merkel cells at the level of the ring sinus in the rat usually terminates as a single, relatively small cluster of endings, whereas in the cat they terminate en passant as several large clusters of endings. Also, individual arbors of reticular endings in the rat ramify parallel to the vibrissae and distribute over wide, overlapping territories, whereas those in the cat ramify perpendicular and terminate in tightly circumscribed territories. Otherwise, the inner conical body of rat FSCs contains en passant, circumferentially oriented lanceolate endings that are lacking in the cat, whereas the cavernous sinus of the cat has en passant corpuscular endings that are lacking in the rat. Surprisingly, the one type of innervation that is the most similar in both species is a major set of simple, club-like endings, located at the attachment of the ringwulst, that had not previously been recognized as a morphologically unique type of innervation. Although the basic structure of the FSCs is similar in the rat and cat, the numerous differences in innervation suggest that these species would have different tactile capabilities and perceptions possibly related to their different vibrissa-related exploratory behaviors.

A comparative study of serotonergic innervation on motoneurons in the brainstem of various mammals (mouse, rat, guinea pig, dog, cat and monkey) was carried out using a sensitive immunohistochemical method. Except for the extraocular muscle nuclei, the motor nuclei of the cranial nerves received rich inputs from serotonin neurons, in all species examined--rodent, carnivore and primate. The motoneurons of the monkey were innervated by varicose serotonin fibers, in a manner different from that of other species, i.e. their cell bodies and proximal dendrites were tightly encircled by a large number of serotonin-containing varicose fibers. At the ultrastructural level, a predominant population of axosomatic contacts was confirmed in the cranial motor nuclei of the monkey, particularly in the nucleus ambiguus.

Zitter mutant rats exhibit abnormal metabolism of superoxide species and demonstrate progressive degeneration of dopamine (DA) neurons in the substantia nigra (SN). Furthermore, long-term intake of vitamin E, an effective free radical scavenger, prevents the loss of DA neurons caused by free radicals. However, it is unclear how this degeneration progresses. In this study, we ultrastructurally examined cell death in the zitter mutant rat SN. Conventional electron-microscopic examination revealed two different types of neurons in the SN pars compacta. In zitter mutant rats, although the first type (clear neurons) exhibited no obvious ultrastructural changes with aging, the second type (dark neurons) demonstrated age-related damage from 2 months. Immunoelectron-microscopic analysis clarified that the second-type neurons were dopaminergic neurons. In the dopaminergic neuronal somata, many lipofuscin granules and abnormal endoplasmic reticula were observed from 2 months of age, and these dopaminergic neurons showed progressive degeneration with age. Moreover, in zitter mutant rats, abnormally enlarged myelinated axons with dense bodies and splitting myelin with dense material were observed in the SN at 2, 4, and 12 months, and oligodendrocytes with numerous lipofuscin, multivesicular bodies, multilamellar bodies, and dense bodies were frequently observed at 4 and 12 months. These findings clarified that dopaminergic neurons in zitter mutant rats had degenerated with age, and that myelinated axons also exhibited age-related injury. Moreover, ubiquitin-immunohistochemical analysis indicated that the accumulation of products of the endosomal-lysosomal system may be involved in this degeneration.

The distribution of serotonin-containing nerve fibers in the substantia nigra of the rat, cat and monkey was studied with a highly sensitive peroxidase-antiperoxidase immunohistochemical method. Serotonin fibers in the substantia nigra of all species consisted of fine varicose fibers and formed a fine network. In the zona compacta of all species, serotonin fibers were sparsely distributed. In the zona reticularis of the rat and cat, these fibers were densely distributed and their distributional pattern was almost uniform, while in the monkey such fibers were unevenly distributed and high and low dense areas were intermingled. In the pars lateralis of all species, serotonin fibers were diffusely distributed, and the distributional density was much higher in the cat and monkey than in the rat. Immunoelectron-microscopic studies further revealed that a majority of the labeled varicosities in the rat substantia nigra were in close apposition to peridendritic axon terminals and were also free in the neuropil; occasionally they exhibited symmetrical synapses of "en passant" type with non-immunoreactive dendrites or somata. Our results support a functional significance of serotonergic regulation of the substantia nigra in mammals.

Biopsied specimens from the human inferior concha were studied histochemically to elucidate the function of the cholinergic nerve fiber, adrenergic nerve fiber, and myoepithelial basket cell and capillary. There are rich cholinergic nerve fibers in the inferior concha. They terminate mainly in the nasal gland and the blood vessels. Lacking in adrenergic nerve fiber, the nasal gland is therefore cholinergic. When the cholinergic nerve is over-stimulated by triggers, such as allergic or other reactions, the nasal gland and vessel work as a functional unit and produce profuse nasal secretion. Studies on human specimens reveal that the greater superficial petrosal nerve, vidian nerve and sphenopalatine ganglion are cholinergic in nature. The anterior ethmoid nerve also contains abundant cholinergic fibers. The nerve fibers in the vidian nerve are mainly cholinergic. The rationale for vidian neurectomy for allergic rhinitis is discussed. Acta Otolai y n g 73Acta Otolaryngol Downloaded from informahealthcare.com by University New South Wales on 08/09/15 For personal use only. Acta Otolaryngol Downloaded from informahealthcare.com by University New South Wales on 08/09/15 For personal use only. Acta Otolaryng 73 Acta Otolaryngol Downloaded from informahealthcare.com by University New South Wales on 08/09/15 For personal use only. Acta Otolaryng 73 Acta Otolaryngol Downloaded from informahealthcare.com by University New South Wales on 08/09/15 For personal use only. Acta Otolaryng 73 Acta Otolaryngol Downloaded from informahealthcare.com by University New South Wales on 08/09/15 For personal use only.