William F. Marovitz

The role of cellular degeneration in the normal development of (rat) otocyst

From day 12 to 16 of gestation a highly circumscribed zone of cellular degeneration has been observed in the otocyst of more than 50 normal rats. This zone appears to be produced by selective or programmed cell death, and results in the elimination of unneeded cellular elements. That cells in this zone are also selectively destroying subcellular organelles as a first step in specialization is also discussed.

An Evaluation of Normal Strial Capillary Transport Using the Electron-Opaque Tracers Ferritin and Iron Dextran

Enzymatic tracer techniques to study normal and pathologic strial capillary transport pose various problems. The use of electron opaque tracers can circumvent many of these problems. Iron dextran (mol. diam 20--70 A) and ferritin (mol. diam 110 A) were injected intravenously and the mice sacrificed at intervals of 1/2, 1, 2, 5, and 24 h. The iron dextran results were unusual in that from 1/2 to 5 h after administration the tracer was present within the cytoplasmic matrix of endothelia, but by 24 h it had been cleared out. No transendothelial exchange was noted. The ferritin results were in conflict and previous results using horse-radish peroxidase. Transport of ferritin was minimal regardless of time sacrificed. No more than a few molecules were scattered about the capillary basal limina. Those molecules transported across capillaries were apparently delivered by means of the micropinocytotic system. The results suggest a blood-strial barrier similar to the blood-thymic and blood-myenteric barriers. Experimental as well as control animals exhibited strial light cells which contained ferritin-like particles within their cytoplasmic matrices. These light cells are probably reticuloendothelial type cells. Ferritin may be useful to gauge strial capillary transport alterations associated with auditory pathologies.

The evaluation of middle ear meningiomas using computerized axial tomography.

Meningiomas localized within the middle ear and mastoid which have no intracranial component are rare tumors. Three patients with meningiomas which were thought to involve only the middle ear were treated surgically, were followed for two to six years and were thought to have been cured. However, when computerized axial tomography became clinically available, these patients were examined using this radiographic technique. Unexpectedly, all three patients were found to have a large intracranial meningiomatous extentiion, A review of the literature reveals only 13 primary meningiomas; these case reports are summarized. It was noted that definitive tests for an intracranial extension of the meningioma were performed in only 2 of the 13 cases. Therefore, in view of our recent clinical experience, it is recommended that a patient presenting with a middle ear meningioma should have a computerized axial tomographic examination of the head to detect the possible presence of a clinical silent intracranial involvement.

Single mitotic center for rodent cochlear duct.

The pattern of terminal mitosis in mouse otocyst observed by Ruben led him to postulate the existence of a growth zone at the junction of saccular and cochlear primordia. With the use of colchicine, an antimitotic drug, a localized zone of mitotic activity has been demonstrated at this predicted site.

Presence of acidic protein-bound carbohydrates in the endolymphatic sac and duct of fetal, neonatal and adult rats, and adult humans.

Seymour’* felt that the endolymphatic sac was an auxiliary site of endolymph production, “to insure complete filling of the phylogenetically older utriculus and semicircular canals.” C i r n i n ~ , ~ working with rabbit embryos described glandular structures in the pars rugosa, and felt that the endolymphatic sac produced endolymph during prenataI life. This secretory activity of the sac in rabbits was felt necessary to assure early endolymphatic filling of the primitive labyrinthine cavities.

Intercellular Junctions in the Differentiating Rat Otocyst

Intercellular junctions between cells of the rat otocyst on the 12th day of gestation were studied using lanthanum tracer and freeze-fracture techniques. At the luminal surface, the intercellular space is closed by a series of tight junctions. Gap junctions are also present between cells both within and below the luminal junctional complex. The presence of tight and gap junctions at this early stage in the differentiating otocyst is probably essential for the development of a normally functioning adult ear.

Salivation testing in traumatic facial paralysis.

When to explore for traumatic facial paralysis has been based upon time of onset and changes in nerve excitability testing. This study indicates that testing for submandibular salivary flow is the method of choice for making a decision to operate. Thirty consecutive patients with traumatic facial paralysis were studied for the prognostic value of whether time of onset was immediate or delayed. Immediate onset has a poorer prognosis than when the onset is delayed but time of onset is not completely reliable. Seventeen percent of the patients with an immediate onset had complete return and 29% with a delayed onset had an incomplete return. Nerve excitability testing was more accurate than time of onset but the test has a major limitation. There was a delay of up to three days between injury and the first detection of nerve excitability abnormality in patients who had an incomplete return. The salivation test performed by cannulating the submandibular salivary gland ducts and comparing the flow in terms of number of drops from each side overcame the time delay limitation of the nerve excitability test. Decrease in salivation to 25% or less when comparing the normal to the paralyzed side tended to antedate abnormal nerve excitability by several days in patients with serious nerve damage. Experimental sectioning of the facial nerve in a group of animals demonstrated immediate loss of salivary flow on the injured side whereas nerve excitability did not become abnormal until two days later. Two patients with traumatic facial paralysis were operated based upon a reduced salivary flow of 25% or less before nerve excitability became abnormal. Both had complete return of facial function. Three patients with a salivary flow of 25% or less who were not operated later developed abnormal response to nerve excitability and had incomplete return of facial function. The salivation test should be included in the prognostic evaluation of patients with traumatic facial nerve paralysis since it may be the earliest indicator for decompression of the nerve.

A Ferritin-containing Cell Type in the Stria Vascularis of the Mouse Inner Ear

This report describes a new cell type within the stria vascularis of the mouse inner ear. The cell is similar ultrastructurally to the classically described intermediate cell. However, it can be distinguished by the presence of dense vacuoles, presumably lysosomes, within which can be visualized electron dense particles resembling ferritin molecules. In addition, the ferritin-like particles are present throughout the cytoplasm and occasionally within the endoplasmic reticulum. These cells characteristically abut capillary basal lamina. Electron probe analysis of the dense vacuoles revealed the presence of iron. It is suggested that these cells may sequester iron released from dying erythrocytes in the strial capillary system, whereupon the iron is conserved through ferritin synthesis.

Evaluation of tympanic neurectomy and chorda tympanectomy surgery.

Thirty patients were treated by tympanic neurectomy, chorda tympanectomy, or both for a variety of conditions. Out of six patients with gustatory sweating treated by tympanic neurectomy, two patients were relieved of symptoms, two were improved, and two remained unchanged. In five cases of benign recurrent painful parotid swelling, only two patients noted improvement in symptoms. Seventeen patients suffered from drooling. Out of 12 postresection head and neck patients, 5 (41%) were improved following such surgery. Two of four cerebral palsy children initially had a good result. However, the long-term follow-up of the patients demonstrated that the drooling recurred. An additional patient who suffered from drooling caused by bulbar weakness following a cerebrovascular accident had fewer problems with salivary secretions postoperatively. The pertinent anatomy and pathophysiology is outlined. The possible reasons for the relatively disappointing results achieved are discussed.

3. Scanning Electron Microscopic Appearance of Rat Otocyst of the Twelfth Postcoital Day Elaboration of a Method

A method for removal, fixation, microdissection, and drying of early rat otocyst for examination by the scanning electron microscope is elaborated. Tissues were dissected, fixed as for conventional transmission electron microscopy and dried by critical point evaporation using amylacetate as the transitional fluid and carbon dioxide as the pressure head. Otocysts were either dissected at the time of initial fixation, or subsequent to drying. The otocyst of the 12th postcoital day was used as a model system in this preliminary report. Critical point drying retained the overall configuration and the fine ultrastructural detail of the otocyst. The interior otocystic surface was visualized and cilia bearing cells of the luminal surface were identified. Most if not all of these cells had a conspicuous, but short kinocilium which terminated in an ovoid bulb. The scanning electron microscopic appearance was correlated to the transmission electron microscopic image seen in the second paper in this Supplement.