M. Ciges

Ultrastructure of the Organ of Jacobson and Comparative Study with Olfactory Mucosa

The organ of Jacobson has been studied in lizards, rats, guinea pigs, rabbits and dogs by means of embedding in nitrocellulose, semithin sectioning, and electron microscopy. The various elements of the organ in the species studied have been analysed and a comparative study carried out between the sensory portion of the organ and the olfactory epithelium.

Ultrastructural Study of Taste Buds at Rest and After Stimulation, and Comparative Study Between Type III Cell and Merkel Cells

Changes in the pore region of the cell membrane have been studied in order to learn if this region plays an active part in the preneural phase of taste. We have observed, though not consistently, that the pore size is variable and that their contents are not constantly amorphous or homogeneous. The results are not so significant, however, as to allow of the formulation of any firm conclusions. The similarity between type III cells and Merkel cells (cells of the tactile system) was surprising. The probable role of the type III cell in taste is discussed.

Pantothenic Acid and Coenzyme A in Experimental Cisplatin-Induced Ototoxia

We have observed that pantothenic acid (PA) prevents deafness induced by cisplatin (CP) in the guinea pig if both drugs are administered jointly. When deafness was previously produced, recovery was sometimes obtained after the administration of PA; so, we studied the effects of PA on cisplatian-induced ototoxia in guinea pigs, both as a prophylactic agent in healthy animals, and as a therapeutic agent in animals previously made deaf by the drug. To elucidate why PA protects the ear from the toxic effects of CP, we used coenzyme A (CoA) instead of PA-since PA is a component of CoA-to test the hypothesis that the action of PA is due to CoA. The results were practically the same in both experiences, the compound action potential of the auditory nerve (CAP) was tested and cochleas were examined by scanning electron microscopy (SEM). Our results suggest that the protective effect of PA takes place through CoA. Both substances had the same effect on CP ototoxicity, but CoA appears to be much more active, since the dose tested here was much lower than that of PA.

The crystalline pattern of calcium in different topographical regions of the otoconial membrane. An electron probe and spectroscopic diffraction study.

Quantitative electron probe microanalysis and electron spectroscopic diffraction analysis was used to determine the gradient of distribution of calcium and its crystalline pattern at different levels (lower gelatinous membrane, upper gelatinous membrane and otoliths) in the otoconial membrane of adult OF1 mice. Our quantitative electron probe microanalytical data, obtained with scanning-transmission electron microscopy, indicated that there was a gradient in calcium concentration which increased from the vestibular surface towards the otoliths. Differences between the three regions of the otoconial membrane were statistically significant in both the utricle and saccule. Our results with electron spectroscopic diffraction revealed an increasing crystalline development from the lower gelatinous membrane towards the otoliths. Our findings with both techniques suggest that the gelatinous membrane is involved in the maturation and crystallization of the otoliths.

Mineralization in the Newborn Rat Statoconia: An EDAX Study

Several types of statoconia, differing in size and shape, have been observed in macula utriculi, the smaller ones in the macular periphery. The larger statoconia seem to be formed by the association of smaller units and calcium presence is comparatively higher: In some parts of the marginal zone there exists a granular material in which the presence of calcium is significant.

Study of a temporal bone of Homo heildelbergensis

Conclusions The characteristic features of the Hh specimen conformed to those of other Pleistocene human fossils, indicating strong cranial structures and a heavy mandible. The mastoid was large and suggested a powerful sternocleidomastoid muscle. The inner ear and tympanic cavities were similar in size and orientation, suggesting that their functions were probably similar. Our observations suggest that the left ear of this Hh specimen was healthy. The large canaliculo–fenestral angle confirms that this ancestor was bipedal. It also strongly suggests that Hh individuals were predisposed to develop certain pathologies of the labyrinth capsule associated with bipedalism, in particular otosclerosis. Objective We studied a temporal bone of Homo heidelbergensis (Hh) in order to investigate the clinical and physiological implications of certain morphological features, especially those associated with the evolutionary reorganization of the inner ear. Material and methods The bone, found in a breach of a cave near Málaga in southern Spain, together with Middle–Upper Pleistocene faunal remains, is >300 000 years old. Four analytical methods were employed. A 3D high-resolution surface laser scan was used for anatomical measurements. For the sectional analysis of the middle and inner ears of Hh we used high-resolution CT, simultaneously studying a normal temporal bone from Homo sapiens sapiens (Hss). To study the middle and inner ear spaces we used 3D reconstruction CT preceded by an intra-bone air shielding technique. To examine the tympanic cavities and measure the canaliculo–fenestral angle, we used a special minimally invasive endoscopic procedure. Results The surface, sectional and 3D CT examinations showed that the Hh specimen was generally more robust and larger than the Hss specimen. It had a large glenoid fossa. The external meatus was wide and deep. The middle ear, and especially the mastoid, was large and widely pneumatized. There were no appreciable differences in the position and size of the labyrinthine spaces and tympanic cavity. The dimensions of the semicircular canals were similar to those of the Hss specimen. Endoscopy revealed normal, healthy tympanic walls and an ossicle fragment in the atticum that probably belonged to the body of the malleus. The diameters of the fallopian duct and the tympanic opening of the Eustachian tube were large. The canaliculo–fenestral angle was ≈114°.

Otoconial Mineralization in Post-natal Development

Otoconial mineralization has been studied in the utricle of post-natal rats, i.e. from birth to the 20th day. Calcium microanalytically detected is seen to decrease progressively until, after 20 days, when the level is rather lower than at birth. In the adult animal the calcium value is much higher, which leads us to believe that there is an immediate calcium loss that is later recovered. Calcium in the peripheral areas of the macula is proportionately less than in the central part.

Degeneration and Regeneration Processes in Experimental Facial Nerve Paralysis

Facial nerve paralysis was provoked by compression of its extratemporal portion in rabbits and the degeneration and regeneration of the nerve fibres was studied ultrastructurally. The compression was removed to study the regenerative process in one group of animals. Axonal and myelin degeneration were the first events seen as a collagen tissue proliferation from the endoneurium and perineurium. Ultimately all the nerve was transformed into fibrous tissue. The myelin was disintegrated by Schwanns cells without any macrophagic activity. The regeneration process begins by the axons, that are orientated towards Büngners bands of remnants of the Schwanns cells, in which a new myelin sheath appears. Schwanns cells play an important role, in both the degeneration and the regeneration process. The final aspect of the regenerated fibres is similar to normal but they contain more collagen tissue, thinner myelin sheaths, and a greater proportion of unmyelinated fibres.

Effects of Renal Insufficiency on the Cochlear Absorptive-secretory Areas: A Morphological Study in the Mongolian Gerbil

In order to evaluate the effects of experimental renal insufficiency (RI) on the labyrinthine absorptive-secretory areas (ASA), 54 adult Mongolian gerbils were submitted to bilateral nephrectomy or to sham procedure. At different intervals (3, 6, 9, 12, 15, 18, 21, 24 hours) after the surgical procedures, or during the terminal stage (28 h) the animals were decapitated and both temporal bones were dissected to obtain selected specimens of the cochlear ASA. The specimens were processed and analysed by light and electron microscopy. Structurally, RI induced progressive thickening of the epithelial components (stria, prominentia, sulcus); separation by fluid accumulation between stria and mesodermal layer; and frequent dilatation of intraepithelial vessels. Ultrastructurally, diverse signs were observed parallel to the evolution of the RI. After 12 h a progressive enlargement of the intercellular spaces, which was particularly evident in the stria surrounding the vessels and in the other sulcus, was observed. Its latest expression was a marked widening of the basolateral spaces containing a granular substance. After 12 h the formation of large cytoplasmic perinuclear spaces containing small rounded vesicles, probably secondary to fluid accumulation, could be observed in the marginal cells. After 24 h diverse signs of organellar damage became evident (schedule: mitochondrial swelling, lysosome like figures, myelin like figures). In the terminal stage, a general homogenization of the cytosol was common. The findings suggest a definite re-distribution of fluids in the inner ear. A close relationship between renal dysfunction and labyrinthine microhomeostasis is therefore proposed.