Shiro Endo

Fine Structures of Utricle of Developing Chick Embryo Exposed to 2G Gravity

Utricular otoconia of the chick embryos incubated under continuous 2G load were examined under a scanning electron microscope. Morphological changes were confined to the process of otoconial formation and the otoconial size. Otoconial formation was remarkably delayed in the utricle of 2G centrifuged chick embryo. Giant otoconia, which sometimes amounted to over 100 microM in length, existed along the marginal zone of the utricular otolithic membrane. These results indicate that the 2G state influences the otoconical formation.

Epithelial-Myoepithelial Carcinoma of the Nasopharynx

We present a patient with a rare epithelial-myoepithelial carcinoma of the nasopharynx with a typical biphasic histopathologic pattern. Immunohistochemical findings support the concept that the inner cells differentiate to ductal epithelium and the outer cells to myoepithelium. In this patient complete excision of the tumor and reconstruction with a pedicled sternocleidomastoid myocutaneous flap were performed. A DNA diploid pattern from flow cytometric study indicates a favorable prognosis. There was no recurrence nor metastasis for 55 months.

Glycoconjugates in the Otholithic Organ of the Developing Chick Embryo

The presence of glycoconjugates in the otolithic organ of developing chick embryos was investigated histochemically using lectins. On the 6-day-old chick embryo, intense labelling with lectins was observed in the sensory epithelium, on the surface of the epithelium and on the immature otoconia. The otoconia were intensely labelled with lectins at every stage of the chick embryos, while the labelling with lectins in the sensory epithelium became weaker with the maturing of the otoconia. In TEM observation, the secretory granules of the supporting cells of the sensory epithelium were labelled with lectin. The reaction of lectin was more intense in the electronic dense zone of the otoconium than in the electronic lucent zone at every stage of the chick embryos. These findings indicate that the precursors of the otoconia are secreted by the supporting cells of the sensory epithelium and that glycoconjugates play an important role in otoconial formation.

Effects of carbonic anhydrase inhibitor on the otolithic organs of developing chick embryos

Carbonic anhydrase appears to be involved in the process of otoconial formation. The purpose of this investigation was to observe the morphologic change in the surface structure of the otolithic organ in developing chick embryos after injection of the carbonic anhydrase inhibitor, acetazolamide. Acetazolamide (1.5, 3, or 6 mg/0.06 mL/egg) was injected into the yolk sac of the embryo of the fifth day of incubation. Embryo specimens were collected on the 11th, 13th, and 18th days of incubation. The chicks were killed on the third day posthatching, and the surfaces of the otolithic organs were observed under a scanning electron microscope. A marked disturbance in otoconial formation was noted in both utricle and saccule, marked by a decrease or absence of otoconia. A widely exposed meshwork structure of otolithic membrane was observed, with sensory cilia penetrating the meshwork small holes in many instances. There were also several otoconial abnormalities, such as the appearance of only a single giant otoconium, or from several to dozens of giant otoconia, and rough, spongy-surfaced global substances entirely covering the maculae. Clearly, carbonic anhydrase inhibitor (acetazolamide) injected into the yolk sac of developing chick embryos alters and inhibits normal otoconial morphogenesis.

The otolithic organ in the developing chick embryo. Scanning electron microscopic study on the utricular macula.

The long and short axes of utricular maculae were measured to calculate growth curves using an ocular micrometer under stereomicroscope. The mean lengths of the long and short axes on the 6th incubation day were 0.06 mm and 0.05 mm, respectively. Thereafter: 1.00 mm and 0.74 mm on the 11th incubation day; 1.34 mm and 1.03 mm on the 15th incubation day; and on hatching 1.51 mm and 1.07 mm, respectively. The surface structure, particularly the otoconia and the sensory hairs of the utricular maculae, on the 4.5th incubation day to the 7th post-hatching day of White Leghorn chicks were observed with a scanning electron microscope (SEM). A number of microvilli and primary cilium on the inner surface of the otocyst were found between the 4.5th and the 5th incubation day. Immature sensory hairs appeared on the 5th incubation day. The polarity of the sensory hairs became evident on and after the 9th incubation day. Mature sensory hairs were seen all over the utricular maculae between the 1st and the 3rd post-hatching day. Mature sensory hairs were mainly seen near the striola, and immature ones peripherally. Then, the various forms in the maturation phase of sensory hairs were seen between the striola and the periphery. These arrangements suggest some process of maturity from the peripheral region to the central striola region. Immature otoconia were first seen on the 6th incubation day. Mature otoconia were recognized on and after the 11th incubation day, and they were observed on the whole surface of the utricular maculae. Global substances on the macula with a rough surface and spongy structure were observed suggesting otoconial precursors transforming themselves into otoconial crystals.

Ultrastructure of the Chick Vestibular Ganglion and Vestibular Nucleus: A Scanning Electron Microscopic Study

The fine structure of the chick vestibular ganglion and vestibular nucleus was studied in three dimensions using a scanning electron microscope (SEM). NaOH and OSO4 maceration methods were applied to observe the configuration in the mechanically torn specimens. Also, Tanakas aldehyde prefix OSO4-DMSO-OSO4 method (A-O-D-O method) was applied to observe the intracellular structure in the fractured specimens. The surface of the ganglion cell and the nerve processes were seen to be covered with abundant thin fibrous tissues in the specimen treated with OSO4 maceration. This surface fibrous tissue was completely removed with the NaOH maceration method. As a result, the ganglion cell and nerve processes could be seen to be enveloped in the myelin sheath. In the fractured vestibular ganglion treated by the A-O-D-O method, there were three patterns of perikaryal myelination in the vestibular ganglion cells: heavily myelinated, lightly myelinated, and unmyelinated, respectively. In the perinuclear region of the vestibular ganglion cell, well developed and aggregated cytoplasmic organelles such as endoplasmic reticulum, mitochondria, and Golgi apparati were observed. In the perinuclear region of the Schwann cell relatively large mitochondria were characteristically observed. In the fractured view of the vestibular nerves, most of vestibular fibers were compactly myelinated. In the vestibular nucleus, the gathering of the neuronal cells were observed with the NaOH maceration method.

Development of the chick vestibular ganglion and its nerve terminating in the endorgan.

We investigated the morphological maturation of the vestibular ganglion and its dendrites terminating in the sacculus of the chick embryo. The cytoplasm of the ganglion cells had acquired a granular feature due to the abundance of ribosomal clusters and rER by the 13th day of incubation. The myelination of the dendrites occurred before that of the perikarya. Compact myelin of the dendrites was observed on the 13th day of incubation, while that of the perikarya was observed in the 20th day of incubation. Nerve endings of afferent and efferent character were observed first in the sacculus on the 13th day of incubation. Positive immunoreactvity of substance P was observed on the 13th day of incubation. It is suggested that the morphological basis of functional activity is present on or around the 13th day of incubation.

Spindle Cell Hemangioendothelioma of the Submandibular Region.

A rare case of spindle cell hemangioendothelioma (SCH) was reported. The patient was a 62-year-old female, whose chief complaint was a soft nodule on the left submandibular region. She was treated by surgical excision. Pathological diagnosis was SCH. There has been no sign of recurrence to date. This is the first case of SCH at the submandibular region.