Intranuclear Rodlets Research Articles

Intranuclear inclusions in the developing neurons of the rat cuneate nuclei

The ultrastructure of intranuclear rodlets, microtubules, fibrillar lattices and membranous inclusions found in the developing cuneate nuclei of rats is described. Rodlets, ranging in diameter from 96--312 nm and in length from 1--2 micrometer, are made up of tightly packed straight filaments measuring 5--8 nm in diameter. Microtubules with a diameter of 26 nm are clustered together. Fibrillar lattices are made up of fibrils with a diameter of 9 nm arranged in layers or sets. Two to nine sets make up a lattice, with a maximum width of 68 nm, in which the adjacent sets are arranged at an angle to each other. Rodlets and fibrillar lattices occur in 6.8% of the neurons. Membranous inclusions, reported here for the first time in normal neurons, are of 2 types: small vesicles of 0.1--0.6 micrometer and large vacuoles measuring 1--2 micrometer. Both types are bounded by either a single or a double membrane and generally have an electron lucent content. Membranous inclusions occur in 25.3% of the neurons. Changes in the frequency of occurrence of the various intranuclear inclusions in the course of postnatal development are also reported.

The Merkel Cell in Oral Human Mucosa

A study of the mucosal Merkel cells from 10 patients showed that the cell contained an intranuclear rodlet, clear cell qualities, fine desmosomes, characteristic membrane-bound Merkel granules, and cellular "horns" and had a close relationship to terminal axons. The Merkel cell is an intraepithelial cell with features of neurons and of amine-storage cells.

Intranuclear rodlets in retrochiasmatic area neurons of the hypothalamus of the rat

Microfilamentous spindle-shaped nuclear rodlets are described in neurons of the retrochiasmatic area in the rat hypothalamus. The authors consider these structures as normal and dynamic nuclear inclusions of these neurons, although their significance remains unknown.

THE MERKEL CELL SYSTEM AND A COMPARISON BETWEEN IT AND THE NEUROSECRETORY OR APUD CELL SYSTEM

The Merkel cell, a neural crest migrant to the skin, possesses a characteristic intranuclear rodlet, cytoplasmic membrane-bound granules, and horn projections and is usually associated with nerve terminations. It is also associated with all types of known organizations of sensory nerve endings in the skin and possesses characteristic enzyme reactions in relation to the ending. The Merkel cell is found in the skin and the oral mucous membranes, and similar cells are observed in the taste buds and pulmonary tissue. A comparison between the Merkel cell and the APUD cell system of polypeptide hormone and amine-producing cells reveals many structural and chemical similarities.

Intranuclear rodlets in an intrathyroid tumor associated with hyperparathyroidism.

A tumor excised from the thyroid gland has been shown by electron microscopy to contain distinctive, intranuclear rodlets. This is the first report of such rodlets in a non-neuronal human tumor. While the parathyroid-like hormonal activity, histopathology, and clinical course are consistent with a parathyroid adenoma, the finding of the rodlets raises the question of origin from a special, neuron-related cell of the parathyroid or thyroid. The unusual cellular granularity and the abundant interstitial fibrillae also suggest an unusual cell of origin. Alternatively, a special metabolic activity may account for the rodlets, or they may have been overlooked in prior studies of adenomas.

An ultrastructural study of the red nucleus in the rat.

The red nuclei of 14 adult male rats of the Wistar strain were prepared for electron microscopic study following perfusion with a mixture of aldehydes, Neurons of four size categories were identified in 1 mu Epon sections and their ultrastructural characteristics were studied in adjacent thin sections. Giant (greater than 40 mu) and large (26-40 mu) neurons are distinguished primarily by size and possess similar ultrastructural features: extensive areas of rough endoplasmic reticulum (RER), a prominent perinuclear Golgi complex, numerous mitochondria and pigment granules and a large, ovoid nucleus which occasionally contains intranuclear rodlets. Medium size neurons (20-25 mu) have less extensive, poorly organized RER and randomly distributed Golgi complexes. The nuclear envelopes of these cells frequently show multiple invaginations and continuity with the RER cisternae. In small neurons (less than 20 mu) the RER occurs as single or anastomosing strands whi le golgi complexes and pigment granules are few. In both medium size and small neurons, aggregates of condensed chromatin are adherent to the inner nuclear membrane. Three main types of synaptic terminals may be distinguished in the red nucleus: (1) small terminals with flattened vesicles and symmetrical densities (F terminals), (2) small terminals with rounded vesicles and asymmetrical densities (RS terminals), and (3) large (10-15 mu) asymmetrical, rounded vesicle terminals which form multiple contacts along their length (RL terminals). The small neurons receive both F and RS terminals on their dendrites and infrequently on their cell somas. The large and giant neurons receive F, RS and RL terminals on their somas and proximal dendrites and F and RS terminals on their distal dendrites. The somas and dendrites of medium size neurons receive both F and RS terminals but RL terminals do not lie in relation to them. Spine contacts are common throughout the nucleus and occur on both somas and dendrites.

Histological and ultrastructural changes in the pars distalis of the rabbit pituitary in organ culture.

SUMMARY Typical histological and ultrastructural changes that occur in the pars distalis of the rabbit pituitary after different periods of organ culture are described. The best technique for the maintenance of the maximum proportion of the explant was assessed by comparing cultures grown under different conditions. Explants in air with a medium buffered with N-2-hydroxyethylpiperazine-N1-2-ethanesulphonic acid (HEPES), not previously used in organ culture, proved more satisfactory than explants in carbogen with bicarbonate-buffered 199, and cultures were maintained for more than 3 weeks. The survival of cells was assessed on the basis of their cytological integrity; DNA- and RNA-fluorescence with acridine orange was a valuable indicator. Prolactin cells, which were few in uncultured controls, became the most common type of granular cell in long-term cultures. Cell modifications during culture included the development of a peripheral epithelioid layer and the appearance of numerous microvilli. Microfibrils, coated or smooth vesicles, lytic bodies, desmosomes and intranuclear rods became more common and intranuclear rodlets (fibrous or membranous structures) were identified. Cells often became more electron dense during long-term culture. Though there was an increase in the number of agranular cells during culture, identifiable granules were retained by many cells throughout culture.

A Merkel Cell Nuclear Inclusion

Unusual inclusions of various structural types have been known to exist in the nuclei of some cells. However, their observation with the electron microscope is an infrequent occurrence. Intranuclear inclusions in brain cells represent the vast majority at reported observations. While studying the ultrastructure of the Merkel cell in human oral epithelium, we noted a unique intranuclear inclusion in several cells. This structure appeared to be identical to an intranuclear rodlet which has been described as occurring frequently in neurons of the primary olfactory system of the cat.

Close association between nuclear rodlets and chromosomal fibers.

Examination of glutaraldehyde or chrome-osmic perfused normal and X-irradiated olfactory bulb has revealed the presence of intranuclear rodlets in the irradiated granules and mitral cells and occasionally in the normal external granule cells. A close association between the filaments of the rodlets and chromosomic neighboring microfibrils was observed.

Histochemical studies of the intranuclear rodlet in neurons of chicken sympathetic and sensory ganglia.

Intranuclear rodlets in chicken sympathetic and sensory neurons have been analyzed histochemically and found to be composed largely of protein with which small amounts of bound lipids or related compounds may be associated. These filamentous formations appear to contain neither DNA, RNA, free lipids (acidic or neutral), nor polysaccharides in amounts demonstrable by standard techniques. Among the amino acids comprising the rodlet protein are arginine, lysine, histidine, tyrosine, tryptophan, and possibly aspartic and glutamic acids; glycine and cysteine may also be present in small amounts.

Origin, development, and nature of intranuclear rodlets and associated bodies in chicken sympathetic neurons.

Correlative data are presented here on the developmental history, dynamics, histochemistry, and fine structure of intranuclear rodlets in chicken sympathetic neurons from in vivo material and long-term organized tissue cultures. The rodlets consist of bundles of approximately 70 +/- 10 A proteinaceous filaments closely associated with approximately 0.4-0.8 micro spheroidal, granulofibrillar (gf) bodies of a related nature. These bodies are already present in the developing embryo a week or more in advance of the rodlets. In early formative stages rodlets consist of small clusters of aligned filaments contiguous with the gf-bodies. As neuronal differentiation progresses these filaments increase in number and become organized into well-ordered polyhedral arrays. Time-lapse cinemicrography reveals transient changes in rodlet contour associated with intrinsic factors, changes in form and position of the nucleolus with respect to the rodlet, and activity of the gf-bodies. With the electron microscope filaments may be seen extending between the nucleolus, gf-bodies, and rodlets; nucleoli display circumscribed regions with fine structural features and staining reactions reminiscent of those of gf-bodies, We suggest that the latter may be derivatives of the nucleolus and that the two may act together in the assemblage and functional dynamics of the rodlet. The egress of rodlet filaments into the cytoplasm raises the possibility that these might represent a source of the cell's filamentous constituents.

Intranuclear inclusion bodies in neurons of aging rats

Intranuclear rodlet shaped structures similar to those recently observed in human multiple sclerosis biopsy material were found in cortical neurons of aging rats. The morphology of these structures is described and their possible significance discussed.