Matti Anniko

Temporal bone morphology after systemic arterial perfusion or intralabyrinthine in situ immersion—I. Hair cells of the vestibular organs and the cochlea

Abstract The morphological preservation of hair cells of the inner ear was analysed following fixation with intra-arterial perfusion or local intralabyrinthine in situ immersion using six different fixatives of glutaraldehyde (441–876mosm/kg), three fixatives with combinations of glutaraldehyde/paraformaldehyde (917–1196mosm/kg) and 1% osmic tetroxide (346mosm/kg). The influence of added macromolecules such as dextran to the buffer solution was investigated with regard to fixation technique and type of fixative. The best results were obtained when using a direct (local) immersion of the labyrinth with 1% osmic tetroxide. Vascular perfusion is not recommended, independent of type of fixative used. Cochlear outer hair cells and vestibular hair cells type I are more vulnerable to alterations of osmolality and fixation technique than are inner hair cells and hair cells type II.

DNA ploidy and cell phase in human pituitary tumors

The flow‐cytofluorometric technique for nuclear DNA analysis was used in the study of 47 consecutive cases with pituitary tumors. The material consisted of 18 tumors secreting growth hormone (GH), 10 secreting GH and prolactin (PRL), 10 prolactinomas, 2 secreting thyroid‐stimulating hormone (TSH), 2 secreting ACTH, and 5 were nonsecreting. An aneuploid DNA pattern occurred in 23 of 47 (49%) cases ranging from 1.4 to 3.6 N thus deflecting from the normal diploid 2N chromosome content of somatic nonreproductive cells. In four tumors two cell lines occurred, but one of them was always dominant, comprising 80% to 90% of all cells analyzed which totally amounted to 20,000 to 30,000 cells. The highest percentage of aneuploid tumors occurred in those with a concomitant secretion of GH and PRL (8 of 10, 80%). The percentage of diploid cells in tumors with an aneuploid nuclear DNA content was very low, 2.3±2.9% (±0.65% SE). In 11 cases with aneuploidy, diploid cells were not detected. The mean age in patients with diploid and aneuploid tumors was rather similar in the different endocrinologic types of tumors.

Postnatal maturation of cochlear sensory hairs in the mouse

SummaryThe surface morphology of inner hair cells in the cochlea of the mouse is fully developed at birth. At this time a regular pattern of elongated microvilli covers the surfaces of outer hair cells at all levels of the cochlea. The sensory hair on outer hair cells undergo a morphological maturation during the first days postnatally. A mature surface morphology is reached 5–7 days after birth. There are two gradients in hair cell maturation in the cochlea: (1) basal to apical, and (2) from inner hair cells to the 3rd row of outer hair cells. Polarization of sensory hairs on an outer hair cell, i.e. polar differentiation of the sensory hairs in the radial direction, occurs as a stepwise increase in length of those facing the stria vascularis.

Experimentally (Atoxyl) Induced Ampullar Degeneration and Damage to the Maculae Utriculi

Atoxyl administration to guinea pigs may cause vesicular degeneration of both the secretory and the sensory regions of the cristae ampullares and macula utriculi. Some of the severely damaged secretory cells were even expelled from the surface into the endolymphatic space. The nerve chalices of type I hair cells disintegrated. The degeneration of the secretory region will thus block the endolymph circulation and the electrolyte balance is likely to collapse. Whether hair cell degeneration can best be explained on this basis (indirect atoxyl effect) or by a direct action of atoxyl on the hair cells and the nerve chalices of type I hair cells is discussed.

Vestibular hair cell pathology in the Shaker-2 mouse

SummaryThe circling-waltzing behaviour of the Shaker-2 mouse is suggested, at least in part, to be of peripheral origin. In this hereditary inner ear disease, degeneration of hair cells type I has been observed showing specific pathologic features: rod-shaped inclusion bodies and sensory hair fusion. Later, the hair cells type I are expelled into the endolymphatic space. A large number of sensory cells type II are morphologically normal. The failure of earlier investigators to demonstrate pathological changes in the sensory epithelia of this animal is likely to be due to the use of light microscopical methods only.

Rods of actin filaments in type I hair cells of the shaker-2 mouse

ZusammenfassungShaker-2-Mäuse leiden an einer erblich bedingten Erkrankung, die sich in einer Taubheit und in einem Schüttel-Dreh-Verhalten äußert. Die Haarzellen vom Typ I in den Cristae ampullares und in den Maculae utriculi zeigen spezielle pathologische Veränderungen. So zeigen sich Zusammenklumpungen der Stereozilien neben stabförmigen Einschlußkörperchen. Die Einschlußkörperchen bestehen aus Filamenten, die als Actinprotein mit Hilfe einer Ankopplung von S-1-Myosin-Bestandteilen identifiziert werden konnten. Die Polarität wurde bestimmt und die Spitzen weisen nach apikal, d. h. vom Kern in Richtung zur Cuticularplatte hin. Diese Beobachtungen stimmen mit früheren überein, die bei Meerschweinchen mit der gleichen Erbkrankheit gefunden wurden. Daraus kann man schlußfolgern, daß die gleichen pathologischen Befunde in den Zellen von zwei unterschiedlichen Tierarten darauf hinweisen, daß die pathologische Veränderung in einem grundsätzlichen Prozeß für die Entwicklung dieses Haarzelltyps verantwortlich ist.SummaryThe shaker-2 mouse with inherited inner ear disease suffers from deafness and a shaking-waltzing behavior. The hair cell type I in cristae ampullares and maculae utriculi show a specific pathology, featuring fusion of the stereocilia and presence of a rod-shaped inclusion body. The inclusion body is composed of filaments that could be identified as the protein actin by the method of decoration with subfragment S-1 of myosin. The functional polarity was determined, and S-1 fragments were found to point apically, that is, from the nucleus up toward the cuticular plate. These observations are identical to those earlier described in the waltzing guinea pig. It is concluded that the identical pathology at a cellular level in two different species may indicate a pathologic disorder in a process fundamental to the normal development of this type of hair cell.

Adenylate cyclase activity in the fetal and the early postnatal inner ear of the mouse

The adenylate cyclase activity was analyzed in fetal, early postnatal and adult inner ears of the CBA/CBA mouse and also in approximately one month old inner ears from Shaker -1 and Shaker -2 mice. A comparison was made with the maturation of potassium levels in endolymph as investigated with the X-ray energy dispersive technique. Adenylate cyclase activity in the developing normal inner ear shows two significant periods of increases: from the 16th to the 19th gestational day in both the cochlear and vestibular parts of the labyrinth, and from birth to day 6 after birth in the lateral wall tissues of the scala media. During the first period the anatomical boundaries of the secretory epithelia are developing. The postnatal rise in adenylate cyclase activity correlates with the morphological maturation of stria vascularis at the cellular and subcellular levels and the rise in potassium content of endolymph. The rise of enzyme activity in the cochlear during the maturation of endolymph supports a link between adenylate cyclase and the control of inner ear fluids. Adenylate cyclase activity in stria vascularis/spiral ligament of Shaker -1 and Shaker -2 mice were at normal levels and correlated better with the rather normal morphology of the tissues than the abnormal composition of endolymph in these mutants.

Pattern formation of the otic placode and morphogenesis of the otocyst

The early embryonic development of the inner ear anlage, from the otic placode stage to formation of the otocyst, was documented in CBA/CBA mice by scanning electron microscopy. The otic placode is identified at the eight- to ten-somite stage, as revealed by the surface morphology of the developing ectoderm. The cells in the otic depression are considerably smaller than those of the adjacent ectodermal surface. Rapid invagination of the otic anlage occurs during the ninth gestational day (approximately eight to 20 somites). In most specimens from the tenth gestational day, the otic vesicle has closed toward the ectodermal surface. The surface of the otocyst on the 13th gestational day shows considerable specialization, with regional differences of the surface structure.

Cochlear Pathology Following Exposure to Mercury

The sensory and secretory epithelia may become morphologically changed following the exposure to mercury chloride. The earliest and most sever change in the sensory epithelium appeared in the apical part of the cochlea, while the basal coils were only seldom damaged (cytocochleogram studies). Acute intoxication mostly affected both afferent and efferent nerve terminals and the hair cells, while chronic poisoning could also damage the stria vascularis.

The influence of different fixatives and osmolality on the ultrastructure of the cochlear neuroepithelium.

SummaryTo investigate which fixative is most suitable for the preservation of cochlear hair cells three main groups of fixatives were used:1.3% glutar aldehyde in various buffers (osmolality altered).2.Glutar aldehyde/paraform aldehyde combination (ad modum Karnovsky).3.Osmic acid solutions (OsO4) in veronal acetate buffer according to Rhodin (1954). The 2% osmic acid fixative (350–370 mosm/kg) resulted in an excellent ultrastructural preservation; an acceptable result was obtained with a 3% glutar aldehyde fixative in 0.1 M sodium phosphate buffer, 600–700 mosm/kg and the Karnovskys fixative.