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M Kemali

Publications and source records attributed to M Kemali.

At least 55 records · Page 3Linked to original sources
PubMed1979

The variety of synaptic vesicles in the interpeduncular nucleus (ITP) of the frog.

The electron microscope has revealed a large variety of synaptic vesicles in the interpeduncular nucleus (ITP) of the frog "Rana esculenta". They vary in shape, size and electron density. There are two types of synapses which show only translucent spherical vesicles: in one type the vesicles are 40 nm, in the other type they are 70 nm in diameter. In other types of synapses the translucent vesicles may be mixed with those with dense core. Large granules, 160 nm in diameter, already reported in the ITP (KEMALI 1977a), are also shown as well as tiny flat mixed with large flat dense core vesicles of dumb-bell shape. Two types of axo-axonic synapses are illustrated while no crest synapses have been demonstrated. The results suggest that the afferents to the ITP might be more numerous than those reported in the literature or that--as in the case of the habenular afferents which consist of cholinergic and peptergic fibres--each projecting nucleus to the ITP has different types of fibres with more than one type of transmitter. Furthermore, due to the vesicles sizes, we may consider the ITP as a site in the vertebrate central nervous system where conventional neurotransmitter structures coexist with probable neurohumoral elements.

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PubMed1978

Non-ependymal cilia in the habenulae and the interpeduncular nucleus of the frog tadpole.

Cilia of the 9 + 2 pattern are found electron microscopically in nonependymal cells of the habenulae and the interpeduncular nucleus of the tadpole of Rana esculenta at an early stage of development (8 mm length, head to tip of tail). A comparison is made between these and the ependymal and sensory cilia in the same specimens. The cilia project into the neuropil emerging from a perikaryon rich in free ribosomes and displaying a prominent Golgi apparatus. These perikarya contain dense core vesicles. Synapses with vesicles of the clear spherical type have been observed along the ciliary shaft. On a purely morphologic basis the authors hypothesize that these cilia, at least in this early ontogenetic stage, may extend considerably the conducting surface of the cell and represent a sensory structure which could be stimulated by terminal processes belonging to distantly located cells. In addition, they could also be involved in the trophic exchange of material with the adjacent structures.

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PubMed1977

An electron microscope observation of the right and the two left portions of the habenular nuclei of the frog.

The right dorsal habenula (RDH), the left dorsal habenula, lateral portion (LDH-LP) and the left dorsal habenula, medial portion (LDH-MP) of the adult frog Rana esculenta have been studied by the electron microscope with the use of three types of fixatives: osmium tetroxide, aldehydes and potassium permangarate. The study has demonstrated in the habenulae of both sides a variety of syraptic vesicles, special synaptic patterns (en passant, serial, axo-somatic) containing small spherical transparent vesicles, never mixed with other types of vesicles, and large pale processes containing big granules. However, a particular type of synaptic vesicles characterized by small clear spherical vesicles with a tiny dark granule revealed by potassium permanganate fixition has been demonstrated only in the neuropil of the LDH and not in the RDH. Further, a peculiar type of intracytoplasmic inclusion appears in the form of myelin-like and crystal-like formations only in the LDH-MP. On the basis of these consistent ultrastructural differences, the dorsal habenular nuclei of the frog can be considered as composed of three individual nuclei, each with its own morphological characterization, dislocated, for some unknown reason, one on the right and two on the left side of the epithalamus. The results suggest that the LDH-MP is a nucleus metabolically different from the others and that the projections to the dorsal habenular nuclei are different on the right and left sides of the brain.

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PubMed1977

The interpeduncular nucleus (ITP). Ultrastructure data indicative of a possible neurosecretory activity.

Special types of cells of the interpeduncular nucleus (ITP) in the fog, Rana esculenta, are described after three typed of fixation: osmium tetroxide, aldehydes and potassium permanganate. Large granules with a sub-unit structure occurring together with bundles of filaments and elongated mitochondria are illustrated in the processes of cells, the perikarya of which lie distant from the ependymal lining of the aqueduct of Sylvius. Such processes cross the ITP in a dorso-ventral direction perpendicular to the fibers which traverse the nucleus in a horizontal and frontal plane. They reach the subpial ventral surface of the nucleus ending in foot-like expansions where granules and mitochondria are assembled. The secretory nature of the granules is assumed. The release of possible peptide hormones into the interpeduncular cistern, where a pool of cerebrospinal fluid and large blood vessels occur, cannot be excluded.

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PubMed1976

Topological analysis of the brain stem of the frogs Rana esculenta and Rana catesbeiana.

The ventricular sulcal pattern and the cytoarchitectonic organization of the brain stem of the frogs Rana esculenta and Rana catesbeiana have been studied in transversely cut, Nissl stained serial sections. Four longitudinal sulci, the sulcus medianus inferior, the sulcus intermedius ventralis, the sulcus limitans and the sulcus medianus superior could be distinguished in both species. A fifth longitudinal groove, the sulcus intermedius dorsalis, was found only in Rana esculenta. With the aid of the usual cytoarchitectonic criteria 25 cell masses have been delineated in Rana esculenta and 27 in Rana catesbeiana. These cell masses can be distributed over the following categories (numbers added in brackets for Rana catesbeiana, if different from those in Rana esculenta): primary efferent or motor, 8; primary afferent or sensory, 4(6); "relay" centers, 7. Contrary to statements in the literature the reticular formation can be divided into six separate cell groups. The majority of the nuclei form part of the central gray, which constitutes a rather wide zone in anurans; three reticular nuclei lie partly within the stratum griseum and partly within the stratum album; six nuclei are entirely embedded in the stratum album. The morphological pattern of the cell masses and their relationship to the ventricular sulci were studied with the aid of a graphical reconstruction procedure termed topological analysis (cf. Nieuwenhuys, '74 and figs. 15, 16). This analysis yielded the following results: The sulcus limitans extends throughout the rhombencephalon, dividing this brain part into a basal plate and an alar plate. The cell masses in the basal plate fit into two longitudinal zones, a medial area ventralis and a lateral area intermedioventralis. The area ventralis contains three somatic motor nuclei (IV, VI and XII) and the rhombencephalic medial reticular zone. The latter may be primarily considered as a somatic motor coordinating center. The area intermedioventralis contains the visceral motor nuclei of V, VII, IX and X. However, the basal plate also contains a number of non-motor centers, for example the superior olive. The alar plate contains visceral sensory, general somatic sensory and special somatic sensory centers. Two cell masses, the nucleusfasciculi solitarii and the nucleus visceralis secundarius, represent together a discontinuous visceral sensory zone. Both of these nuclei are situated immediately dorsal to the sulcus limitans. The special somatic sensory area, i.e., the area of termination of the eighth nerve, occupies a considerable part of the alar plate. This area comprises, apart from a large zone of diffuse gray, three distinct cell masses...

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PubMed1976

A modification of the rapid Golgi method.

An extremely rapid Golgi procedure for immersion impregnation of the whole brain of the frog Rana esculenta is described. It uses an isotonic 2% osmium tetroxide solution buffered with sodium barbital at pH 7.2 that has previously been used for electron microscopy. To 15 ml of this solution 85 ml 3% potassium dichromate is added just before use. Twelve-hour treatments (6 hr in the chrome-osmium solution plus 6 hr in 0.75% silver nitrate) are sufficient to obtain consistently excellent impregnations of external brain formations. Twenty-four-hour treatments (12 hr in the chrome-osmium solution and 12 hr in the silver solution) impregnate also the deeper regions of the brain. The results show neuronal details on a clear background.

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PubMed1975

Ciliated glial cells and neurons in the interpeduncular nucleus of the frog.

Some neurons and glial cells of the interpeduncular nucleus of the adult frog Rana esculenta contain one cilium. The cilium complex shows two-centriole basal organization. Cross striated structures are seen apposed to the centriolar formations. The centriole and associated basal body are always close to the vesicular elements of the Golgi apparatus in the neurons and are surrounded by quite a number of microtubules in the glial cells. The observations suggest that these ciliated cells represent specialized elements in which the cilium has probably the same functional transport properties postulated for cytoplasmic microtubules.

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