C. Diaz

Neck dissection with or without postoperative radiotherapy in supraglottic carcinomas.

A retrospective review of 302 previously untreated patients with primary supraglottic carcinoma was undertaken to ascertain the efficacy of postoperative radiotherapy. The 302 patients underwent a total of 383 functional neck dissections and 45 classic radical neck dissections. Pathological examination revealed nodal involvement in 117 patients (39%). In the histologically N0 group, the incidence of contralateral neck recurrence when a unilateral neck dissection and postoperative radiotherapy were carried out was 8%, rising 21% when no postoperative radiation was given. There was no difference in the ipsilateral recurrence rate in the N0 group, radiated patients (3%) and nonradiated patients (2%). Similar figures were found in the N1 group. Bilateral functional neck dissection in histologically N0, N1, and N2 necks had similar recurrence rates with or without radiotherapy. Distant metastasis appeared in 10% of N0 patients and in 35% of N3 patients. Patients who received postoperative radiotherapy showed a significantly higher rate of distant metastasis (21%) than patients who did not (8%). The number of involved lymph nodes had no relevance both in neck recurrence and distant metastasis.

Neuronal loss in human medial vestibular nucleus

The data concerning the effects of age on the brainstem are inconsistent, and few works are devoted to the human vestibular nuclear complex. The medial vestibular nucleus (MVN) is the largest nucleus of the vestibular nuclear complex, and it seems to be related mainly to vestibular compensation and vestibulo‐ocular reflexes.

Aging and the human vestibular nuclei: morphometric analysis

The data concerning the effects of age on the brainstem are scarce and few works are devoted to the human vestibular nuclear complex. The study of the effects of aging in the vestibular nuclei could have clinical interest due to the high prevalence of balance control and gait problems in the elderly. We have used in this work eight human brainstems of different ages sectioned and stained by the formaldehyde-thionin technique. The neurons profiles were drawn with a camera lucida and Abercrombies method was used to estimate the total number of neurons. The test of Kolmogorov-Smirnov with the correction of Lilliefors was used to evaluate the fit of our data to a normal distribution and a regression analysis was done to determine if the variation of our data with age was statistically significant. Aging does not affect the volume or length of the vestibular nuclear complex. Our results clearly show that neuronal loss occurs with aging in the descending (DVN), medial (MVN), and lateral (LVN) vestibular nuclei, but not in the superior (SVN). There are changes in the proportions of neurons of different sizes but they are not statistically significant. The neuronal loss could be related with the problems that elderly people have to compensate unilateral vestibular lesions and the alterations of the vestibulospinal reflexes. The preservation of SVN neurons can explain why vestibulo-ocular reflexes are compensated after unilateral vestibular injuries.

Morphometric analysis of the vestibular complex in the rat

The characteristics of the four major vestibular nuclei and accessory cell groups in the rat have been studied in serially cut horizontal sections. Camera lucida drawings of the vestibular nuclei and their neurons were made in these sections and subjected to a computerized image analysis. The dimensions (volume and length) and the number of cells of each vestibular nucleus were obtained, as well as morphometric parameters of their neurons (cross-sectional area, maximum and minimum diameter, and shape). These parameters were statistically analyzed by comparing the cell population from different nuclei and different parts of each nucleus. Of the major nuclei, the medial, which is the largest, has the greatest number of cells, its neurons being the smallest of all the nuclei, with the size of cells decreasing in a rostrocaudal direction. In contrast, the lateral nucleus contains the fewest cells but also the largest ones. Neurons of the superior and descending nuclei are of an intermediate size and number, with a rostrocaudal decrease in the size of the descending nucleus cells. In addition, minor nuclei are identified and described in their relationship to the other structures in the brain stem. The relevant aspects of the anatomical information in regard to functional roles are reviewed.

MORPHOMETRIC ANALYSIS OF THE HUMAN VESTIBULAR NUCLEI

Cytoarchitectural investigations of the vestibular nuclei have been undertaken in different species of mammals. These data provide a description of the general architecture of the nuclei but limited information about quantitative characteristics of their cell population. We have recently obtained data about the morphometric parameters of the vestibular nuclei neurons in some species. The application of quantitative image analysis techniques to the research of the cellular morphology in the vestibular area of humans might provide basic information to compare with data from animal studies, taking into account the observed correlation between physiological and morphological properties of vestibular neurons.

Rostrocaudal and ventrodorsal change in neuronal cell size in human medial vestibular nucleus.

The present paper describes the cytoarchitectonic, morphometric, and three‐dimensional characteristics of the human medial vestibular nucleus (MVN). We also studied the regional distribution, in size, of the different neurons and its possible relationship with a functional polarization of the different regions of the nucleus.

Rostrocaudal changes in neuronal cell size in human lateral vestibular nucleus

A cytoarchitectonic and morphometric study of the human lateral vestibular nucleus (LVN) is presented. In sagittal sections, the LVN appears as a triangular cell group rostrally located near the motor trigeminal nucleus and caudally near the vestibular root. The estimated volume is 13.49 mm3 with a neuronal population of 25,046 cells and 1855 neurons/mm3 in density. The average neuronal cross-sectional area changes from a minimum caudally (380.02 +/- 7.23 microns 2) to a maximum rostrally (825.16 +/- 25.10 microns 2). Four types of neurons can be observed: small (< 200 microns 2), medium (200-500 microns 2), large (500-100 microns 2) and giant or Deiters cells (> 1000 microns 2). The small and medium cells constitute 62%, large cells 26% and the giant cells only 12% of the neuronal population.

Circadian changes in synaptic ribbons and spherules in pinealocytes of the Syrian hamster (Mesocricetus auratus).

SummaryIn the present study, “synaptic” ribbons were studied morphologically and quantitatively in hamster pineal gland. The number of ribbons and spherules of hamster pinealocytes was counted over a 24-h period. The 24-h variations in the quantity of “synaptic” ribbons were found to parallel fluctuations in pineal melatonin concentrations. No significant circadian changes were observed for “synaptic” spherules, indicating different roles for these two structures.

The Pineal Gland of Mammals: Some Open Morphological Questions

The pineal gland derives from the dorsal wall of the diencephalon and presents a varied structure in the different vertebrate species. In fish, amphibians and reptiles the ultrastructure of its main cell type, the pinealocyte, is similar to that of photoreceptor cells of the vertebrate retina and to the sensory organs of invertebrates that respond directly to light.

Cell loss in human vestibular nuclei related to aging

The protein kinase C (PKC) family of enzymes constitutes at least 10 different isoforms that display a variety of distinct biochemical specificities. Many of these isoforms are highly expressed in brain and some show regional specificity in their distribution, which suggests that they may serve specific functions. Using methods standard in our laboratories (Garcia et al., 1993), we used immunocytochemistry to localize the 13I, 1311, 7 and 8 isoforms of PKC in the central vestibular system of the adult rat. Antibodies to PKC-131, 1311, and 7 were gifts of Dr. William Wetsel (NIEHS); the antibody to PKC-~ was purchased from R&D Abs (Berkeley, Calif.). We found the vestibular ganglion and its peripheral and central processes of the VIIIth nerve to be heavily immunostained with the PKC 131 antibody. Labeled axons and terminals were found in all four vestibular nuclei. The myelinated fiber bundles of the spinal vestibular nucleus contained many well-labeled axons. In addition, numerous well-labeled neurons were found in the medial vestibular nucleus, with smaller numbers of labeled neurons found in the other vestibular nuclei. Some neurons of the vestibular ganglion were weakly stained with the antibody to PKC 1311, as were scattered axons in the VIIIth nerve. Scattered axons and terminals were found in all four vestibular nuclei, among weakly-labeled neurons. With the antibody to PKC-y, we observed a few labeled axons in the vestibular portion of the VIIIth nerve. Neurons of the spinal, lateral, and superior vestibular nuclei were heavily decorated with synapses, presumably derived from Purkinje neurons, which were also strongly immunoreactive. Neurons of the medial vestibular nucleus were not as heavily innervated by PKC-7 afferents. With the antibody to PKC-& we found scattered, weakly immunoreactive neurons in the vestibular portion of the VIllth nerve. Myelinated fiber bundles of the spinal vestibular nucleus contained moderate numbers of labeled axons. The other three vestibular nuclei were well-innervated by PKC-~ axons and terminals, most of which probably derive from Purkinje cells, which were labeled in longitudinal bands interspersed with bands of labeled basket ceils. These data suggest that particular PKC isoforms play specific roles in vestibular function. (Supported by a grant from the Deafness Research Foundation to MMG.) Poster 42