Wincenty Kilarski

The fine structure of striated muscles in teleosts

SummaryThe organization of skeletal and cardiac muscles of fishes described on the basis of observations carried out on several species of freshwater fishes (Tinca tinca, Misgurnus fossilis, Perca fluviatilis, Lebistes reticidatus) and marine fishes (Gobius minutus, Pleuronectes platessa, Ammodytes tobianus). Truncal, subcutaneous, extrinsic eye and cardiac muscles were used for study. Glutaraldehyde-fixed tissue was refixed in OsO4, embedded in Epon and after polymerization, cut into ultra thin sections and examined by an electron microscope.White and red muscles were distinguished in the material examined. The latter was represented by subcutaneous muscles and small fibres of extrinsic eye muscles. Particular types of fibers differ from each other in their organization of the SR and localization of the T system tubules. In the most muscles the T system tubules are situated at the level of the Z line. In the small fibers of extrinsic eye muscles alone these tubules lie at the A-I junction.The myocardiac cells consist of a cylindrically shaped myofibril. In the middle of the cylinder is the nucleus, the remaining space being filled with numerous mitochondria. A loose sarcoplasmic network is twined around the myofibril.

Training‐induced acceleration of O2 uptake on‐kinetics precedes muscle mitochondrial biogenesis in humans

•  What is the central question of this study? A few weeks of endurance training accelerate the oxygen uptake () on‐kinetics in humans. The main aim of the present study was to determine whether the acceleration of on‐kinetics obtained by a short period of moderate‐intensity training can be explained by an intensification of mitochondrial biogenesis. •  What is the main finding and its importance? We demonstrated that 5 weeks of moderate‐intensity training accelerates the on‐kinetics during moderate‐intensity cycling in the absence of enhanced mitochondrial biogenesis or capillarization in the trained muscles. We postulate that in the early stages of training an intensification of ‘parallel activation’ of oxidative phosphorylation could account for the shortening of the on‐transient.

Organization and fine structure of extraocular muscles in Carassius and Rana

Summary1. Two types of muscle fibers, red (-slow) and white (-twitch), have been described in the extraocular muscles of Carassius and Rana, respectively. 2. Red and white muscle fibers occupy a definite position in particular eye muscles and occur in almost constant numerical relation. 3. The red fibers in the fish extraocular muscles are supposedly slow. The position of the triads is at the level of the A/I junction, whereas that of the white muscle fibers is at the Z line level. 4. In the frog the extraocular muscles consist of two types of muscle fibers, which have morphological features of slow and fast fibers, respectively, the triads being localized at the Z line level.

Balbiani cytoplasm in oocytes of a primitive fish, the sturgeon Acipenser gueldenstaedtii, and its potential homology to the Balbiani body (mitochondrial cloud) of Xenopus laevis oocytes

The oocytes of many organisms, including frogs and fish, contain a distinct cytoplasmic organelle called the Balbiani body. Because of the scarcity of published information and the tremendous variability in the appearance, ultrastructure, and composition of Balbiani bodies between species, the function of the Balbiani body and its inter-species homology remain a mystery. In Xenopus laevis, the Balbiani body is known to play a role in transporting germ cell determinants and localized RNAs to the oocyte vegetal cortex. In fish, however, the molecular composition of the Balbiani body has not been studied to date, and its function remains completely unknown. We have studied the ultrastructure and molecular composition of previtellogenic oocytes of the sturgeon, Acipenser gueldenstaedtii, by using electron microscopy, in situ hybridization, and immunostaining. We have found that sturgeon oocytes contain two distinct zones of cytoplasm: homogeneous (organelle-free) and granular (organelle-rich). We have also found that the granular ooplasm, which we term the Balbiani cytoplasm, shares important homologies, in both ultrastructure and molecular composition, with Xenopus Balbiani bodies.

Yolk-platelet crystals in three ancient bony fishes: Polypterus bichir (polypteri), Amia calva L., and Lepisosteus osseus (L.) (Holostei)

SummaryYolk-platelet crystals in Amia calva L., Lepisosteus osseus (L.) and Polypterus bichir have orthorhombic features with unit-cell dimensions a= 8.3...8.8 nm, b= 16.4...16.9 nm and c= 18.6...19.8 nm as determined in electron-diffraction patterns of fixed, epoxy-resin embedded and thinsectioned material. Electron-diffraction patterns, crystal projections and the above unit-cell data make them extremely similar to the orthorhombic yolkplatelet crystals known for amphibians and teleosts. This observation fills a gap in yolk-platelet research and supports the view that the general architecture of yolk platelets has been conserved for nearly 400 million years. It follows that the peculiar platelet architecture itself has physiological significance.

Histochemical characterization of the muscle fiber types of the Teleost (Esox lucius L.).

On the base of the actomyosin ATP-ase activity and succinate dehydrogenase (SDH) activity, 4 types of muscle fibers were described in the pike (Esox lucius L.) body musculature. Besides the typical red, intermediate, and white fibers, probably other fibers discerned were of tonic type. Another fibers found were the intermediate fibers of a characteristic small diameter and localization beyond the intermediate fiber zone. This particular construction of the body musculature is characteristic for darting behaviour fish.

Acetylcholinesterase and acetylcholine receptor histochemistry on end plate regions, myotendinous junctions, and sarcolemma in the axial musculature of three teleost fish species

In this paper we describe a rapid procedure for the identification of motor end plates in fish. We demonstrated the presence of acetylcholine receptors by means of an immune fluorescence technique with alpha-bungarotoxin. Koelles thiocholine method was used to localize acetylcholinesterase (AChE) activity. Under carefully controlled conditions the AChE activity and the anti-alpha-bungarotoxin fluorescence showed an equal distribution. This means that in the study of motor innervation in fish the AChE reaction can be used to stain only the motor end plates, leaving the AChE rich preterminal axons unstained. Comparison of the AChE reaction pattern with the distribution of binding sites for antibodies raised against neurofilament protein revealed that in end plate regions high concentrations of AChE are only present in axons and end plates. The myotendinous junctions also possess a high receptor density and enzyme activity. A low enzymatic activity was found at the non-junctional periphery of white muscle fibres. This activity probably resides in the sarcolemma. No non-specific cholinesterase activity was found. From light microscopical analysis it appeared that a single end plate may innervate 2 adjacent muscle fibres. This was affirmed by ultrastructural observations. The dual innervation suggests that, in fish, motor units have a limited distribution through the myotome.

Cytomorphometry of sarcoplasmic reticulum in extrinsic eye muscles of the teleost (Tinca tinca L.).

SummaryThe sarcoplasmic reticulum of the white and red muscle fibers in the extrinsic eye muscle of the tench (Tinca tinca L.) differs in its organization. The SR of the white fibers is organized according to the Z type, the SR of the red fibers according to the A/I type. In order to estimate the volume and surface of the SR component in both types of muscle fibers, a stereological analysis was carried out.The volume of the SR expressed as a volume density (VvSR) is twofold greater in the white than in the red muscle fibers. The surface of the SR, expressed as surface density (SvSR) is 20,5% larger in the white muscle fibers.

Histochemistry and isomyosins of tail musculature inXenopus

SummaryThe main bulk of the larval tail inXenopus laevis is composed of thick muscle fibres which are succinate dehydrogenase (SDH) negative and show strong positive ATPase activity only at alkaline preincubation (pH 10.4). The thin muscle fibres (which cover the surface of the myotomes and extend to the tail tip) show positive SDH activity as well as strong positive ATPase activity after both alkaline and acid preincubations (pH 10.4, 4.5, 4.4, and 4.3). The pattern of myosin isoenzymes does not change in the tail muscle in the course of development ofXenopus: the same three bands of larval isomyosins were found in all the examined developmental stages: 40, 47, 50 and 56. However, the larval bands were distinct from three bands of myosin isoforms in the musculus longissimus dorsi (MLD) and musculus grastrocnemius (MG) of the metamorphosedXenopus.

Morphometric analysis of gap junction density in human myometrium at term

In the human myometrium. the formation of gap junctions in the various stages of labor and, in correlation with the concentration of progesterone in the maternal blood, has not been described adequately. The accepted hypothesis that raised concentrations of progesterone in maternal blood in animals prevent the formation of gap junctions was scrutinized in human niyometrium. Myometrial tissue was examined by electron microscopy for the presence of gap lunctions and analyzed morphometrically in 17 women who had an elective or emergency cesarean operation at the 38th or 39th week of pregnancy. The concentrations of progesterone and estradiol in the maternal and cord blood was measured by means of radioimiiiunoassay. The frequency and area of gap junctions varied in relation to the presence or absence of labor. In the myometrium of women in labor, gap junctions were most frequent (5.2/1000 μm of cell membrane), their area largest (0.32 μ2/1000 μm of cell membrane) and their fractional area greatest (0.20%). When the women were not in genuine labor or when contractions were weak, the percentage fractional areas of gap junctions were low (0.020‐0 090) and the gap junctions very small. In the pre‐ and active phases of labor, the concentration of progesterone in maternal blood was significantly higher (p <0.025 and 0.03 respectively) than in women who were not in labor.