Muscle Spindle Composition and Distribution in Human Young Masseter and Biceps Brachii Muscles Reveal Early Growth and Maturation

Significant changes in extrafusal fiber type composition take place in the human masseter muscle from young age, 3–7 years, to adulthood, in parallel with jaw‐face skeleton growth, changes of dentitions and improvement of jaw functions. As motor and sensory control systems of muscles are interlinked, also the intrafusal fiber population, that is, muscle spindles, should undergo age‐related changes in fiber type appearance. To test this hypothesis, we examined muscle spindles in the young masseter muscle and compared the result with previous data on adult masseter spindles. Also muscle spindles in the young biceps brachii muscle were examined. The result showed that muscle spindle composition and distribution were alike in young and adult masseter. As for the adult masseter, young masseter contained exceptionally large muscle spindles, and with the highest spindle density and most complex spindles found in the deep masseter portion. Hence, contrary to our hypothesis, masseter spindles do not undergo major morphological changes between young age and adulthood. Also in the biceps, young spindles were alike adult spindles. Taken together, the results showed that human masseter and biceps muscle spindles are morphologically mature already at young age. We conclude that muscle spindles in the human young masseter and biceps precede the extrafusal fiber population in growth and maturation. This in turn suggests early reflex control and proprioceptive demands in learning and maturation of jaw motor skills. Similarly, well‐developed muscle spindles in young biceps reflect early need of reflex control in learning and performing arm motor behavior. Anat Rec, 2011. © 2011 Wiley‐Liss, Inc.     

Cytoskeletal identification of intermediate filaments in the inner ear of the jerker mouse mutant

The expression of the five main groups of intermediate filaments (IF) and their subgroups, especially cytokeratins, was analysed in cryosections of the labyrinth of the jerker mouse mutant and compared with normal CBA/CBA controls. Fourteen different well characterized monoclonal antibodies were used. In principle the same pattern of IF was found in the two mouse strains. IF were not found in hair cells of the mouse inner ear, which may reflect a disparity as compared with human fetal hair cells. Chain-specific (epitope-specific) differences were visualized in cytokeratin no. 8 with regard to cells in epithelia involved in the homeostasis of inner ear fluids. Differences in immuno-staining occurred between adjacent cells in the same epithelium, for instance in the semicircular canals.     

Adult human masseter muscle fibers express myosin isozymes characteristic of development

Masseter muscle biopsies were obtained from nine patients undergoing orthognatic surgery or surgery for parotid tumors. A detailed enzyme-histochemical and immunocytochemical study of these muscles was performed using antibodies specific to the various isozymes of the myosin heavy chain (MHC) in order to identify the MHC isozymes that were present in the different fiber types. The contractile proteins in these same biopsies were analyzed by two-dimensional gel electrophoresis, native pyrophosphate gel electrophoresis, and by an immunopolypeptide mapping approach. These studies have shown that there is a very heterogeneous distribution of the myosin isozymes, with many fibers containing more than one myosin type. We also present evidence that in addition to adult fast and slow myosin, the human masseter muscle contains two proteins, neonatal MHC and embryonic myosin light chain, that are characteristic of developing muscle.     

Long-term prognosis of post-infectious renal scarring in relation to radiological findings in childhood — a 27-year follow-up

In a previous report the long-term prognosis of 30 patients with renal scarring after pyelonephritis in childhood was described. In this study, we have related the extent of renal scarring present in childhood to the conditions in early adulthood. A radiological progression of searring from childhood to adulthood was seen in one-third of the kidneys. The 7 patients with bilateral scarring in childhood had a smaller renal area, lower glomerular filtration rate and higher plasma vasopressin at follow-up than 13 healthy controls. The 20 patients who had unilateral searring in childhood had a smaller renal area, lower glomerular filtration rate, higher diastolic blood pressure and higher plasma renin at follow-up than controls; 4 had hypertension. The most important finding was that children with unilateral disease are at risk of serious long-term complications. Filtration fraction at follow-up was higher in patients with extensive renal scarring in childhood compared with those with a normal renal area or small scars in childhood (r=–0.43,P<0.05). This may indicate glomerular hyperfiltration by remnant glomeruli. This paper emphasizes the potential seriousness of childhood urinary tract infections especially when early infantile infections are overlooked. A follow-up of more than 4 decades may be necessary before the ultimate prognosis can be established, especially in patients with unilateral renal disease. It is advised that most patients with post-infectious renal scars are followed as high-risk patients, and that treatment continuity is established between paediatricians, nephrologists and, when required, obstetricians.to Author for further revision and received in revised form May 28, 1991     

Regional variations in the expression of cytokeratin proteins in the adult human cochlea

Summary In the adult human cochlea, a cytokeratin (Ck) network exists along the entire surface of the organ of Corti, enclosing it like a shell. Only the surfaces of the outer and inner hair cells are not integrated in this network. In temporal bone specimens, Ck filaments in Hensen's cells were found to be arranged parallel with and closely apposed to the plasma membrane. In the stria vascularis, Cks were identified only in the marginal cells. Cells in Reissner's membrane and spiral prominence showed varying degrees of immunoreactivity to different monoclonal antibodies directed against Cks. A distinct positivity for Cks was found in most spiral ganglion cells, indicating their presence in all cells. The principal pattern of immunoreactivity was the same in the organ of Corti of the entire cochlea. However, a quantitative gradient in the expression of Cks was observed, with more Cks at the apex than at the base. This was correlated to a difference in the number of Hensen's cells between the two regions. The distinct shell configuration of the Ck network in Corti's organ gives it a tonotopically related difference in rigidity which must be of considerable importance for the perception of sound in the cochlea. The absence of Cks in inner and outer sulcus cells gives them cytoskeletal characteristics of mesenchymal cells with a possible regenerative potential.Supported by grants from the Swedish Medical Research Council (M. A.: 12X-7305; L.-E. T.: 12X-3934), the Ragnar and Torsten Söderberg Foundation (M. A.), the Foundation Tysta Skolan (M. A.), the Swiss National Funds (W. A., C. R. P.: 3.997-1.86), the Finnish Cancer Research Fund (I. V.), the Sigrid Juselius Foundation (I. V.), the Dutch Cancer Foundation (K. W. F.) and the Medical Faculty University of Ume»     

Purkinje fibre glycogen a morphologic and biochemical study of glycogen particles isolated from the cow conducting system

Glycogen from the cow conducting system was extracted by crude and mild methods. For comparison similar extractions were also performed on cow ordinary ventricular tissue. Glycogen particles from the conducting system, isolated by a mild method, were characterized by a low molecular weight (3-5 X 10(6)) and small dimensions (average diameter about 30 nm). 3.5-7% protein was firmly bound to the glycogen. The glycogen, based on spectrophotometric analysis, appeared to be in a native state. Glycogen as a polysaccharide-protein complex can thus be obtained from the cow conducting system and is proposed to be useful for analysis of the structure and function of glycogen in the conducting system.     

An ultrahistochemical study on glycogen in cow Purkinje fibres

Ultrahistochemical staining with periodic acid-thiosemicarbazide-silver proteinate (PA-TSC-SP) indicated that cow Purkinje fibres are rich in glycogen in the form of round to oval particles, about 20 nm in diameter. Alignment or grouping of the glycogen particles was evident. Three types of 20 nm particles were distinguished by their different densities in sections stained with UAc and PbCi. The densest variety was interpreted to be ribosomes, and less dense particles in association with cytoplasmic filaments and very faintly stained particles between the filaments were considered to represent glycogen. The special character of glycogen in Purkinje fibres may be partly due to interactions between glycogen particles or between glycogen particles and filaments. Polysaccharide deposits were occasionally seen intercellularly, between Purkinje fibres. These deposits may be artefacts due to the preparative procedure, or to biological degeneration.