Teething during sleep: Ultrastructural analysis of pharyngeal muscle and cuticular grinder during the molt in Caenorhabditis elegans.

Complex extracellular structures exist throughout phylogeny, but the dynamics of their formation and dissolution are often opaque. One example is the pharyngeal grinder of the nematode Caenorhabditis elegans, an extracellular structure that ruptures bacteria during feeding. During each larval transition stage, called lethargus, the grinder is replaced with one of a larger size. Here, we characterize at the ultrastructural level the deconstruction of the larval grinder and the construction of the adult grinder during the fourth larval stage (L4)-to-adult transition. Early in L4 lethargus, pharyngeal muscle cells trans-differentiate from contractile to secretory cells, as evidenced by the appearance of clear and dense core vesicles and disruptions in sarcomere organization. This is followed, within minutes, by the dissolution of the L4 grinder and the formation and maturation of the adult grinder. Components of the nascent adult grinder are deposited basally, and are separated from the dissolving larval grinder by a visible apical layer. The complete grinder is a lamellated extracellular matrix comprised of five layers. Following grinder formation, pharyngeal muscle cells regain ultrastructural contractile properties, and muscle contractions resume. Our findings add to our understanding of how complex extracellular structures assemble and dissemble.

Pharyngeal constrictor muscle fatty change may contribute to obstructive sleep apnea-hypopnea syndrome: a prospective observational study.

CONCLUSIONS: Pharyngeal constrictor muscle injury and fatty changes may play important roles in the pathogenesis and progression of OSAHS. OBJECTIVE: Obstructive sleep apnea-hypopnea syndrome (OSAHS) is a respiratory disorder caused by upper airway obstruction during sleep. The primary objectives of this study were to determine the ultrastructural characteristics of the pharyngeal constrictor muscle in patients with OSAHS. METHODS: A pharyngeal constrictor muscle specimen was collected from all subjects. The muscle cell ultrastructure was observed under electron microscopy. RESULTS: Eighteen male patients with OSAHS (OSAHS group) and 10 male body mass index-matched patients with chronic tonsillitis (control group) were enrolled in this study. All patients were obese adults. The apnea-hypopnea index (41.22 ± 17.29 vs 2.30 ± 1.10 events/h) was significantly higher and the lowest arterial oxygen saturation (76.00 ± 8.57% vs 97.00 ± 2.00%) was significantly lower in the OSAHS group than in the control group (both p < 0.001). Myofibril disorder, mitochondrial edema, and intramyocellular lipid droplets were observed in patients with OSAHS. There was a significant correlation between the number of lipid droplets and the apnea-hypopnea index.

[Pathologic changes of the palatopharyngeal muscles in patients with obstructive sleep apnea hypopnea syndrome of different degrees].

OBJECTIVE: To study the pathologic changes of the palatopharyngeal muscles with transmission electronmicroscopy (TEM) in patients with obstructive sleep apnea hypopnea syndrome (OSAHS), the role of the above muscle in OSAHS pathogenesis was discussed. METHODS: Thirty-eight palatopharyngeal muscle from OSAHS patients receiving uvulopalatopharyngoplasty (UPPP) were collected in in-patient department of Chinese Medical University and five palatal tumor patients receiving resection without snoring were chosen as the control. The palatopharyngeal muscle fiber and the feature of changes in mitochondrial morphology were observed by TEM. RESULTS: The pathological changes were not observed in the normal control group. The muscle fibers were regularly arranged, and the mitochondrial between muscles were normal. The palatopharyngeal myofibrillar in mild OSAHS group was regularly arranged. The Z lines were straight, and most mitochondria structure were normal. In the moderate group, the myofibrillar was disorganized, and the Z lines were shortened or distorted. The myofibrillar in severe group was disorganized, similar to point-like or flake, and the Z lines and the structures of sarcomeres were disappeared. And organelle were disintegrated and mitochondria were disappeared similar to flocculent. There existed obvious fatty infiltration in the palatopharyngeal muscle. In the control, mild, moderate and severe group, pharyngeal muscle fiber disarrangement of the occurrence rate was 0, 2/10, 8/13, 14/15, the occurrence rate of mitochondrial degeneration was 0, 2/10, 8/13, 14/15, increased with the severity of the ultrastructural changes in the trend of increasing incidence. CONCLUSIONS: The degree of OSAHS is correlated with the pathological changes of palatopharyngeal muscles. Incidence of myopathy is an important part of OSAHS secondary to chronic intermittent hypoxia in OSAHS and other pathological lesions, but also an important reason for increasing pharyngeal collapse.

Structure and evolution of the pharynx simplex in acoel flatworms (Acoela).

The homology of pharynges within the mostly pharynx-less Acoela has been a matter of discussion for decades and even the basic question of whether a pharynx is a primitive trait within the Acoela and homologous to the pharynx of platyhelminth turbellarians is open. By using fluorescence staining of musculature, as well as conventional histological techniques and transmission electron microscopy, the present study sets focus on the mouth and pharynx (where present) of seven species of Acoela within Paratomellidae, Solenofilomorphidae, Hofsteniidae, Proporidae, and Convolutidae, as well as one species of Nemertodermatida and Catenulida, respectively. It is shown that among the investigated families of acoels there is a great variability in muscle systems associated with the mouth and pharynx and that pharynx histology and ultrastructural characters are widely diverse. There are no close similarities between the acoel pharynges and the catenulid pharynx but there is a general resemblance of the musculature associated with the mouth in the representatives of Paratomellidae and Nemertodermatida. On the basis of the profound differences in pharynx morphology, three major conclusions are drawn: 1) the pharynges as present in Recent acoels are not homologous to the pharynx simplex characteristic for Catenulida and Macrostomida within the Platyhelminthes; 2) the different muscular pharynx types of acoels are not homologous between higher taxa and thus a single acoel-type pharynx simplex cannot be defined; 3) the presence of a muscular pharynx most likely does not represent the ancestral state.

Scanning electron microscopic study of the muscle fiber arrangement in the rat cricopharyngeal muscle.

CONCLUSIONS: Myomyous junctions comprise a complex muscle fiber network, which is thought to synchronize the activity of the cricopharyngeal (CP) muscle fibers. Myomyous and myotendinous junctions explain the heterogeneity in muscle fiber length which contributes to the efficient behavior of the muscle. This scanning electron microscopy (SEM) study demonstrated the complex muscle fiber arrangement of the CP muscle and improved on the previous description of its morphological specificity. OBJECTIVE: To examine the 3D ultrastructure of the inferior pharyngeal constrictor muscle fibers to obtain further knowledge of their morphological characteristics with regard to the specific functions of the muscle in deglutition. MATERIAL AND METHODS: Six adult rats were used. Their CP and thyropharyngeal (TP) muscles were obtained and processed using the HCl hydrolysis method to remove i.m. connective tissue. The fine muscle fiber structure was observed by means of SEM. RESULTS: Multifaceted muscle fiber interconnections (myomyous junctions) were identified in the CP muscle. The myomyous junctions were characterized by the tight connection of many finger-like processes at the ends of a lateral branch or bifurcating trunk of the muscle fibers. In addition, muscle fibers occasionally tapered and ended within the muscle belly, forming myotendinous junctions. The TP muscle lacked these structures.

The fetal cleft palate: III. Ultrastructural and functional analysis of palatal development following in utero repair of the congenital model.

The role of fetal surgery in the management of congenital anomalies and intrauterine abnormalities is appropriately restricted on the basis of feasibility and risk-to-benefit analyses of intrauterine intervention. Recently, the authors demonstrated that in utero cleft palate repair of the congenital caprine model is technically feasible and results in scarless healing of the mucoperiosteum and velum, with subsequent development of a potentially functional bilaminar palate with distinct oral and nasal mucosal layers, following single-layer repair of the fetal mucoperiosteal flaps. A slight indentation at the site of repair was the only remaining evidence of a cleft. At 6 months of age, normal palatal architecture, including that of mucosal, muscular, and glandular elements, was seen grossly and histologically. The present work investigated the ultrastructural and functional aspects of the palate following in utero cleft repair to determine what benefits might be derived from fetal intervention. Six goats pregnant with twins were gavaged twice daily for 10 days (gestational days 32 to 41; term, 145 days) with dry, ground Nicotiana glauca plant delivering between 2.4 and 14 mg/kg per day of anabasine, doses that were adjusted in response to mater-nal toxicity. At 85 days' gestation, six fetuses underwent in utero palatoplasty using a modified von Langenbeck technique with elevation of bilateral mucoperiosteal flaps and lateral relaxing incisions. A single-layer repair of the mucoperiosteal flaps was performed using interrupted 6-0 Vicryl sutures. Six fetuses remained as unrepaired clefted controls. Six months after in utero palatoplasty, each group of goats underwent nasoendoscopy to evaluate palatal function; two unclefted 6-month-old goats served as controls. Subsequently, soft palate muscle was harvested from each of the goats and was evaluated by light and electron microscopy. Velar muscle was also harvested from the unclefted control goats and was similarly studied. Nasoendoscopy demonstrated functional palates capable of dynamic velopharyngeal closure following in utero cleft repair; this motion was similar to that observed in unclefted animals. Unrepaired clefted goats did not demonstrate any evidence of velar motion or velopharyngeal closure. Soft palate muscle from this group demonstrated evidence of myofibril degeneration, atrophy, and loss compared with unclefted control velar muscle. Ultrastructural changes included sarcomere "scalloping, " partial Z-line degeneration and loss, and progressive I-band degeneration and loss. Repaired clefted soft palate muscle was remarkably similar to unclefted control muscle. Significantly less myofibril, Z-line, and I-band degeneration and loss were observed with minimal evidence of sarcomere scalloping. In utero cleft palate repair results in a functional soft palate with restoration of ultrastructural architecture of the velum. These findings were attributed to reconstitution of the velar muscular sling, which is disrupted during the clefting process and remains abnormally inserted into the posterior edge of the palatal bone and along the bony cleft. Although repaired velar muscle does demonstrate some evidence of ultrastructural change compared with control muscle, these findings are significantly less pronounced than those observed in the unrepaired clefted muscle.

[Pharyngeal musculature and obstructive sleep apnea syndromes]. / Musculature pharyngée et syndrome d'apnées obstructives du sommeil (SAOS).

An analysis of the way the pharyngeal musculature modulates the caliber of the pharynx is important to better understand and treat obstructive sleep apnea syndromes. The caliber of the pharynx at the soft palate depends on the action of the tensor veli, the palatoglossus, the palatopharyngeus and the uvula muscles. At the ligual level, the action of the genioglossus and the geniohyoideus predominate. These different muscle groups contract in co-ordination before the diaphragm contracts. Their activity is diminished and disorganized during sleep. These muscles appears to have a histological composition adapted to short-duration intense contractions making them vulnerable to fatigue. In apneic patients, these muscles are solicited constantly. Muscular lesions related to overwork have been suggested. The histological composition of these muscles is modified in apneic patients compared with non-apneic subjects (increased number of type IIa fibres), the expression of an adaptive process. The degree of adaptation varies depending of the pharyngeal level considered. Similar to their reflex stimulation, the response of these pharyngeal muscles to increased resistance is probably greatest at the soft palate level. Greater solicitation of palatine muscles associated with their greater vulnerability to fatigue could explain why obstruction is particularly important at this level. A study of the mechanical and histological properties of the pharyngeal musculature is required for a better understanding of the occlusive mechanisms of the upper airways and must be undertaken before initiating therapeutic stimulation of these muscles.

Parvalbumin distribution in the musculature of the pharyngo-oesophageal segment.

The composition and size of muscle fibre types in the hyopharyngeus (HP), thyropharyngeus (TP), cricopharyngeus (CP) and cervical oesophageal muscle (CE) from 6 normal adult cats were investigated using parvalbumin (PA) immunohistochemistry. Fibre types I, IIA and IIB were identified in all muscles. HP and TP revealed predominance of type II fibres (74.8% and 75.2%, respectively), whilst CP and CE showed predominance of type I fibres (72.6% and 82.2%, respectively). The mean diameter of narrow fibres was greater in type II (23.9 microm) than in type I fibres (21.7 microm). The results seem to reflect the physiological features of each muscle, i.e. short rapid contractions of HP and TP, sustained contraction of CP and slow peristaltic movements of CE.

Muscle fiber type distribution in the normal human levator veli palatini muscle.

OBJECTIVE: This study examined the muscle fiber type distribution within the normal adult levator veli palatini muscle. METHODS: Levator veli palatini muscle tissue was harvested from the palates of 12 (seven female, five male) adult noncleft cadavers. Adjacent sections were stained for adenosine triphosphatase at pH 10.4 or 4.2. After mounting, magnifying, and photographing, Type I versus Type II fiber types were differentiated by the intensity of, or by the inhibition of, staining of matched fibers at each pH level. Type I fibers stained light at pH 10.4 and dark at pH 4.2, while Type II fibers stained light at pH 4.2 and dark at pH 10.4. MAIN OUTCOME MEASURES: The number of fibers counted for each specimen ranged from 60 to 616. The numbers of Type I and Type II stained fibers appearing in each muscle tissue sample were determined and expressed as a percentage of the total number of fibers identified. A few identified fibers could not be labelled as either Type I or Type II. RESULTS: The overall proportion of Type I fibers, averaged across all specimens, was 59.8%. Male specimens had 67.4% Type I fibers and 31.8% Type II fibers, while female specimens had 54.4% Type I fibers and 44.4% Type II fibers. CONCLUSIONS: Observed fiber type distributions were similar to those reported for other articulatory muscles, but differed slightly from previously reported distributions for normal levator veli palatini. The distributions observed in this study provide a baseline against which to relate fiber type data from the levator veli palatini of cleft palates to the functional status of the velopharyngeal mechanism.

Autosomal recessive oculopharyngodistal myopathy in light of distal myopathy with rimmed vacuoles and oculopharyngeal muscular dystrophy.

We investigated two Japanese siblings presenting with oculopharyngodistal myopathy, whose healthy parents were consanguineous. To clarify their disease characteristics, we compared them with four patients with distal myopathy with rimmed vacuoles linked to chromosome 9p1-q1, and 36 patients with oculopharyngeal muscular dystrophy linked to 14q11.2-q13. The first symptom in the patients with autosomal recessive oculopharyngodistal myopathy was weakness of the tibialis anterior muscle. Their biceps muscles showed initial and advanced myogenic changes, with rimmed vacuoles in 3% and 6% of the muscle fibers, respectively. In contrast, patients with distal myopathy with rimmed vacuoles revealed many rimmed vacuoles, on average in 20% of the fibers, and their oculopharyngeal muscles were spared. None of the patients with oculopharyngeal muscular dystrophy showed distal dominant weakness and the occurrence of rimmed vacuoles was rare. Ultrastructural studies in groups of autosomal recessive oculopharyngodistal myopathy and distal myopathy with rimmed vacuoles disclosed a collection of cytoplasmic filaments of 16-18 nm, but oculopharyngeal muscular dystrophy-specific intranuclear inclusions of 8.5 nm were not found. Thus, the phenotype of autosomal recessive oculopharyngodistal myopathy is distinct from distal myopathy with rimmed vacuoles and oculopharyngeal muscular dystrophy, but shares some ultrastructural characteristics with distal myopathy with rimmed vacuoles and hereditary inclusion body myopathy.

Intranuclear inclusions in oculopharyngeal muscular dystrophy among Bukhara Jews.

We studied, by electron microscopy, muscle biopsies from seven patients with autosomal dominant oculopharyngeal muscular dystrophy (OPMD) belonging to the recently described Bukhara-Jewish cluster. Typical tubulofilamentous intranuclear inclusions (INI) of 8.5 nm outer diameter were present in all cases. The INI were observed in 4.5 +/- 1.8% of the nuclei in five patients. In the other two, they occurred in 9.5 +/- 0.5% of the nuclei and often occupied a larger nuclear area. These two patients, offspring of intermarriage between affected cousins, had an unusually severe form of OPMD beginning in their early 30s, suggesting homozygote state. Our results confirm that INI are pathognomonic for OPMD and suggest that their frequency may be quantitatively related to the number of abnormal DNA copies.

The occurrence and ultrastructure of a mechanoreceptor in the human cricopharyngeus muscle.

An encapsulated nerve structure resembling the Golgi tendon organ was found in a human cricopharyngeus muscle near the cricoid cartilage where muscle fibers terminate. The capsule consisted of lamellated flattened cells with a basal lamina. Capsular cells separated the lumen into small compartments which contained myelinated and/or nonmyelinated nerve fibers. Nonmyelinated nerve fibers were also found in the interlamellar spaces of the capsular cells. Some nonmyelinated nerve fibers were dilated and contained abundant mitochondria, being partly surrounded by a Schwann cell sheath and embedded in collagen bundles. These features indicate that the nerve structure is a mechanoreceptor similar to the Golgi tendon organ. Its location and structure indicate that it is placed to detect the tension of the cricopharyngeus muscle.

Presence of inclusion body myositis-like filaments in oculopharyngeal muscular dystrophy. Ultrastructural study of 10 cases.

Ten cases of oculopharyngeal muscular dystrophy (OPMD) were examined ultrastructurally. Two very different types of filamentous inclusions were observed: (1) Nuclear inclusions composed of 8.5 nm external diameter tubular filaments organized in palisades and similar to those described by Tomé and Fardeau (1980). They have not yet been reported in other muscle diseases. Their presence in 100% of our cases confirms they are the morphological hallmark of OPMD. (2) 16-18 nm external diameter tubular filaments. These were similar to the inclusions observed in inclusion body myositis (IBM) and morphologically very different from the first type. They were randomly dispersed or arranged in bundles near cytoplasmic debris and whorls of membranes. They were found in cytoplasm. Only once were they observed in a nucleus. These inclusions have been described in IBM but also in other diseases. They were found in 80% of our OPMD cases.

Nuclear inclusions in innervated cultured muscle fibers from patients with oculopharyngeal muscular dystrophy.

We established monolayer muscle fiber cultures from muscle biopsies of 3 patients with oculopharyngeal muscular dystrophy (OPMD) who had characteristic intranuclear inclusions (INI-A) in their muscle fibers. Aneural cultures had normal morphology, except for a few muscle fibers that contained small vacuoles. Innervated cultures had large cytoplasmic vacuoles in a number of muscle fibers. Those muscle fibers were breaking easily, and could not be maintained longer than 2 months. Electron microscopy showed unusual intranuclear inclusions (INI-B) not previously reported in aneurally cultured muscle fibers of OPMD or in any normal or disease-control aneural or innervated cultured human muscle fibers. They resembled, but were not identical to, the INI-A, and they occurred in both the cultured fibers and the original muscle biopsies of all 3 patients. Our study demonstrate that (1) nuclear inclusions in OPMD reflect an intrinsic genetic defect; and (2) neuronal influence, advanced maturation, or both, seem to be essential for their induction in muscle fibers.

Oculopharyngeal muscular dystrophy: recent ultrastructural evidence for mitochondrial abnormalities.

Oculopharyngeal muscular dystrophy is a rare, autosomal dominant disorder which has been traced through 11 generations of a French Canadian family. The classic presenting complaints are palpebral ptosis and oropharyngeal dysphagia. The dysphagia is usually progressive and leads to repetitive regurgitation, increased alimentation time, and weight loss. Immunologic studies generally reveal elevated levels of IgA and IgG, while manometry demonstrates poor pharyngeal contraction. The dysphagia is frequently relieved by cricopharyngeal myotomy. We present two case reports and also a new ultrastructural finding of abnormal metallic mitochondrial inclusions. This finding has not been previously described in this disorder.

Ocular myopathies.

Ocular myopathies are manifested by primary and progressive involvement of extraocular muscles. In most cases of involvement of extra-ocular muscles a biopsy from somatic muscles studied by histochemistry and electron microscopy permits to make the diagnosis of the underlying condition. The two main clinico-pathological types of ocular myopathies are the oculocraniosomatic syndrome (Kearns-Sayre syndrome) and oculopharyngeal muscular dystrophy. The oculocraniosomatic syndrome is a multisystemic disorder and its histopathological hallmark is the presence of ragged-red muscle fibres which contain aggregates of abnormal mitochondria, often with paracrystalline inclusions. In the oculopharyngeal muscular dystrophy are observed muscle fibres with rimmed vacuoles and intranuclear tubular filamentous inclusions about 8.5 nm in external diameter. The rimmed vacuoles may occur in other muscle diseases but the intranuclear inclusions appear to be specific for oculopharyngeal muscular dystrophy. Their nature is unknown.

Dominant mutations affecting muscle structure in Caenorhabditis elegans that map near the actin gene cluster.

By examining F1 progeny of mutagenized Caenorhabditis elegans larvae, we recovered several dominant mutations which affect muscle structure. Five of these new mutations resulted in phenotypes unlike the previously recognized unc-54 and unc-15 dominant alleles. Mapping studies placed all five mutations in the same small region of linkage group V. Polarized light, fluorescence and electron microscopic studies showed that a prominent feature of the disorganized myofilament lattice is the abnormal placement of thin filaments within the body wall muscle cells. Pharyngeal musculature is also affected by three of the mutations when homozygous. Of the five mutations only three are homozygous viable. All three of these have unusually high intragenic reversion rates either spontaneously (approximately 10(-6)) or after ethyl methanesulfonate mutagenesis (2 X 10(-5)), suggesting that reversion occurs through loss of function mutations. No unlinked suppressor mutations were found. The dominance of the mutations, the effect on thin filaments and the reversion properties suggested that these new dominant mutations lie in a gene or genes specifying a structural component of the thin filament. The positioning of a set of three actin sequences in the same region (Files et al., 1983) led us to speculate that these mutations lie in actin genes.

Nuclear inclusions in oculopharyngeal dystrophy. An ultrastructural study of six cases.

Nuclear inclusions in striated muscle from patients with oculopharyngeal dystrophy have been detected recently. We carried out ultrastructural examinations of biopsy specimens on 5 patients with oculopharyngeal dystrophy and we also reexamined a former case. In these 6 cases we found filamentous inclusions in a few nuclei. These inclusions seem to be characteristic of this disease as they have never been seen elsewhere.

Nemaline rods in cricopharyngeal dysphagia.

Cricopharyngeal dysphagia, a disorder of uncertain pathogenesis, is most frequently found in patients with associated gastroesophageal reflux. Seven patients who had dominant cricopharyngeal dysphagia were evaluated. Manometry showed characteristic motor incoordination. Biochemical profiles and endoscopy were normal. Electronmicroscopic examination of the cricopharyngeal muscle biopsy specimens obtained during myotomy showed significant ultrastructural abnormalities. These included numerous and aberrant mitochondria, increased glycogen, lipid inclusions, and phagolysozomes. A striking finding was the presence of numerous nemaline rods in five of seven biopsy specimens examined. The pathologic changes in this muscle in cryopharyngeal dysphagia have not been reported previously. Structural changes are thought to be a secondary response to reflux injury. Nemaline rods form part of the structural abnormality of muscle in patients who have cricopharyngeal dysphasia with no evidence of underlying generalized disease or myopathy.