A histochemical characterization of muscle fiber types in the avian M. stapedius

The muscle fiber types and sizes in the M. stapedius (middle ear muscle) of the domestic chicken, Gallus gallus were determined histochemically on the basis of their reactions to myofibrillar adenosine triphosphatase (mATPase), succinic dehydrogenase and NADH diaphorase. Only type II fibers were identified at pH 9.4 and 4.2. At pH 4.6 three levels of activity were seen: high, intermediate and low. With the staining techniques three subtypes of fibers for oxidative enzymes, Types II1 (highly glycolytic), II12 (intermediately glycolytic and lipolytic) and II123 (highly lipolytic) were identified. Fiber diameter was also measured for the different fiber types. The average fiber diameter was around 20 micron for each fiber type. Although similar in size, the fiber types were markedly different in their histochemical properties. These findings plus those of earlier physiological studies suggest that the M. stapedius of G. gallus is a fast twitch, muscle with fibers of similar diameter showing mainly fatigue resistance characteristics.     

A new type of primary granule in guinea pig heterophil granulocytes

Guinea pig heterophil granulocytes were found to have three types of granules which are formed sequentially during the development of the cells in the bone marrow and differ in shape and electron density: nucleated, azurophil and specific granules. Early promyelocytes proved to synthesize nucleated granules of medium electron density prior to the formation of azurophil granules which are highly electron dense, by late promyelocytes. Since the formation of nucleated granules and azurophil granules is restricted to promyelocytes, both can be considered to be primary granules. The moderately dense specific granules (secondary granules) appear later during granulopoiesis and are firstly present in the myelocyte.     

Histochemical and ultrastructural characteristics of a new muscle fibre type in avian striated muscle

Synopsis The serratus metapatagialis (SMP) muscle of the pigeon has been studied histochemically and ultrastructurally. At the gross anatomical level the SMP is clearly divisible into a peripheral whitish band and a red portion comprised predominantly of pale and red fibres respectively. The pale fibres possess low succinate dehydrogenase, low mitochondrial content, absence of subsarcolemmal mitochondrial aggregates, low fat, moderate glycogen, high phosphorylase, low-to-moderate regular myofibrillar adenosine triphosphatase (M-ATPase), activation of M-ATPase following acid preincubation and jagged Z bands. On the basis of these characteristics, these physiologically slow muscle fibres have been termed Type I white or slow-twitch glycolytic. The SMP red fibres, however, possess high aerobic as well as glycolytic capacity, high M-ATPase activity which is labile after acid preincubation and thick but straight Z bands; therefore, they are the Type II red or fast-twitch oxidative-glycolytic.Some of data in this paper was presented at the Anatomical Society of Australia and New Zealand, 1978.     

A comparative histochemical study of the masseter muscle of the cattle,sheep, swine,dog, guinea pig,and rat

Summary The masseter muscles of different mammals were studied by means of histochemical reactions: NADH: Nitro BT oxidoreductase (NADHOX), 3-hydroxybutyrate: NAD⁺ oxidoreductase (HBOX), glycerol-3-phosphate: menadione oxidoreductase (GPOX), and acid-stable and alkali-stable myosin adenosine triphosphatase (ATPase). The masseter muscles of cattle and sheep consisted only of the fibres that reacted moderately for GPOX and strongly for NADHOX, HBOX, and the acid-stable ATPase. The masseter fibres of rats and guinea pigs reacted uniformly and strongly for GPOX and the alkali-stable ATPase. The fibres of the rats showed a weak to strong reaction for NADHOX and mostly a negative reaction for HBOX, whereas those of the guinea pigs reacted uniformly and strongly for NADHOX and HBOX. The masseter fibres of swine and dogs showed a weak or strong reaction for the alkali-stable and a negative or weak reaction for HBOX. The fibres of the swine were weak to strong in NADHOX activity and those of the dogs uniformly strong; the fibres of the two species gave a moderate to strong reaction for GPOX. The masseter fibres of the ruminant differed from those of the other species in histochemical properties, and appeared to have the histochemical characteristics that meed functional demands for slow, long-term exercise.     

Morphological studies of fiber types of striated muscle fibers of the cremaster in the guinea pig

THe fine structure of the striated muscle fibers of the cremaster of the guinea pig was studied using the cholinesterase technique and light and electron microscopy. Under light microscopy, isolated single muscle fibers showed two types of nerve endings: the first one presented elliptic or oval areas having digit-like structures inside, some of the borders of which were heavily stained. These fibers had only one end-plate. The second type presented elongated clear areas with most of the density located on the borders. Several nerve endings were apparent in these fibers. By electron microscopy, the former had large and numerous sarcolemmal foldings and these characteristics were also observed in unstained fibers. In the latter, the foldings were scanty or absent. At the ultrastructural level, the fibers having only one end-plate presented a regular array of fibrils with an abundant sarcoplasmic reticulum ('Fibrillenstruktur' type) in contrast to the multi-innervated fiber with an irregular distribution pattern of fibrils and a scarce sarcoplasmic reticulum ('Felderstruktur' type). The striated muscle fiber layer of the cremaster probably contains both fast and slow fibers. The possible functional role for the slow striated muscle fibers is discussed.     

A morphologic and histochemical study of the mesentery in the guinea pig

The guinea pig mesentery is a uniform, continuous, thin (18 micron) sheet of connective tissue covered by a single layer of flattened mesothelial cells on both surfaces. Tight and gap junctions provide for cell-to-cell adhesion among mesothelial cells. These cells possess numerous micropinocytotic vesicles; a conspicuous basal lamina separates the mesothelium from the underlying connective tissue. Most of the material found between the two serous coverings consisted of a three-dimensional meshwork of abundant collagenous fibers intermingled with a sparse net of very thin (0.4 micron) elastic fibers. Two distinct populations of collagen fibrils are segregated into different compartments of the mesentery. One population is formed of thick (56 nm) fibrils which associate to form closely packed fibers. The second population, composed of loosely arranged thin (38 nm) fibrils which do not become assembled into fibers, is found underlying the basal lamina that separates the mesothelium from the connective tissue. These observations strongly suggest that the mesentery contains both collagens type I and type III. The guinea pig mesentery contains 6.8 mg of sulfated glycosaminoglycans/g dry weight. Most of these glycosaminoglycans (78%) were identified as dermatan sulfate, whilst the rest (22%) corresponded to heparan sulfate.     

A comparative histochemical study of the masseter muscle of the cattle, sheep, swine, dog, guinea pig, and rat.

The masseter muscles of different mammals were studied by means of hisotchemical reactions: NADH: Nitro BT oxidoreductase (NADHOX), 3-hydroxybutyrate: NAD+ oxidoreductase (HBOX), glycerol-3-phosphate: menadione oxidoreductase (GPOX), and acid-stable and alkali-stable myosin adenosine triphosphatase (ATPase). The masseter mucles of cattle and sheep consisted only of the fibres that reacted moderately for GPOX and strongly for NADHOX, HBOX, and the acid-stable ATPase. The masseter fibres of rats and guinea pigs reacted uniformly and strongly for GPOX and the alkali-stable ATPase. The fibres of the rats showed a weak to strong reaction for NADHOX and mostly a negative reaction for HBOX, whereas those of the guinea pigs reacted uniformly and strongly for NADHOX and HBOX.The masseter fibres of swine and dogs showed a weak or strong reaction for the alkali-stable and a negative or weak reation for HBOX. The fibres of the swine were weak to strong in NADHOX activity and those of the dogs uniformly strong; the fibres of the two species gave a moderate to strong reaction for GPOX. The masseter fibres of the ruminant differed from those of the other species in histochemical properties, and appeared to have the histochemical characteristics that meed functional demands for slow, long-term exercise.     

Microscopical and electrophysiological studies on the healing-over of striated fibers of cremaster muscle of the guinea pig

In previous works it has been shown that the striated fibers of the cremaster muscle undergo a calcium-dependent healing-over reaction after transection and that the fibers of the diaphragm under the same conditions do not recover. In the present work striated fibers of the cremaster and diaphragm are studied, using electrophysiological techniques, light and electron microscopy, 15, 30, 45 and 60 min after transection in an attempt to clarify the process leading to the recovery of the fibers of the cremaster muscle. The recording of membrane potentials at different times after the lesion in the immediate vicinity of the cut end demonstrates that the new diffusion barrier is formed at the damaged surface. Light microscopy of fibers of cremaster transected in vitro indicates the existence of a rapid process preventing the outflow of particulate constituents of the cytoplasm 1 min after the lesion. Electron microscopy shows that this hindrance is due to a compact disposition of filaments derived from altered myofibrils near the cut end. This filamentary plug does not exist in the diaphragm. Cell membrane closing is a slow phenomenon which is completed between 30 and 60 min after the lesion in different fibers. No reconstitution of the cell membrane was found in the fibers of the diaphragm. Rapid and slow responses are interpreted as particular cases of the surface precipitation reaction known in several cell types for more than 40 years.     

Histological and histochemical comparisons of muscle spindles in three hind limb muscles of the guinea pig.

Guinea pig soleus, medial gastrocnemius and vastus lateralis muscles were compared for spindle density and distribution, number of intrafusal fibers per spindle and histochemical appearance of the axial bundle. A total of 326 spindles was used in the comparisons. Spindle density was over four times greater in the soleus than in either the medial gastrocnemius or vastus lateralis. In the soleus the spindles were distributed at random, but in the other two muscles no spindles were found in those fascicles in which fast-twitch glycolytic extrafusal fibers predominated. The average number of intrafusal fibers per spindle varied by less than 5% between the three kinds of muscles. About 80% of all spindles located had four intrafusal fibers, two of the nuclear bag type and two of the nuclear chain type. The histochemical appearance of the axial bundle was the same in each kind of muscle. Based on intensities of the myofibrillar adenosine triphosphatase reaction product at polar regions nuclear bag fibers were separable into two histochemical groups; nuclear chain fibers were of only one histochemical type.     

Immunological relationships of an endogenous guinea pig retrovirus with prototype mammalian type B and type D retroviruses.

A retrovirus endogenous to guinea pig cells was earlier shown to be morphologically similar to type B and type D prototype retroviruses. Molecular hybridization techniques were used to show that guinea pig virus nucleotide sequences are endogenous to both domestic (Cavia porcellus) and indigenous (Cavia aperea) guinea pigs, but cannot be detected in the DNA of either other hystricomorph rodents or other mammals tested. Using radioimmunological techniques designed to detect interspecies relationships, the major internal polypeptide of guinea pig virus (p26) was shown to share three different sets of interspecies antigenic determinants with squirrel monkey retrovirus, viper retrovirus, and mouse mammary tumor virus. Thus, guinea pig virus appears to provide an evolutionary link between type B and D retroviruses.     

Skelemins: cytoskeletal proteins located at the periphery of M-discs in mammalian striated muscle

The cytoskeletons of mammalian striated and smooth muscles contain a pair of high molecular weight (HMW) polypeptides of 220,000 and 200,000 mol wt, each with isoelectric points of about 5 (Price, M. G., 1984, Am. J. Physiol., 246:H566-572) in a molar ratio of 1:1:20 with desmin. The HMW polypeptides of mammalian muscle have been named "skelemins," because they are in the insoluble cytoskeletons of striated muscle and are at the M-discs. I have used two-dimensional peptide mapping to show that the two skelemin polypeptides are closely related to each another. Polyclonal antibodies directed against skelemins were used to demonstrate that they are immunologically distinct from talin, fodrin, myosin heavy chain, synemin, microtubule-associated proteins, and numerous other proteins of similar molecular weight, and are not oligomers of other muscle proteins. Skelemins appear not to be proteolytic products of larger proteins, as shown by immunoautoradiography on 3% polyacrylamide gels. Skelemins are predominantly cytoskeletal, with little extractable from myofibrils by various salt solutions. Human, bovine, and rat cardiac, skeletal, and smooth muscles, but not chicken muscles, contain proteins cross-reacting with anti-skelemin antibodies. Skelemins are localized by immunofluorescence at the M-lines of cardiac and skeletal muscle, in 0.4-micron-wide smooth striations. Cross sections reveal that skelemins are located at the periphery of the M-discs. Skelemins are seen in threads linking isolated myofibrils at the M-discs. There is sufficient skelemin in striated muscle to wrap around the M-disc about three times, if the skelemin molecules are laid end to end, assuming a length-to-weight ratio similar to M-line protein and other elongated proteins. The results indicate that skelemins form linked rings around the periphery of the myofibrillar M-discs. These cytoskeletal rings may play a role in the maintenance of the structural integrity of striated muscle throughout cycles of contraction and relaxation.     

Comparative histochemical investigation of the organ of Corti in the kangaroo rat, gerbil, and guinea pig

The distribution of carbohydrates, proteins, and lipids was studied in the cochleae of kangaroo rat, gerbil, and guinea pig using both fixed paraffin sections and fresh-frozen cryostat sections. Enzyme distribution in the cochleae of the three speices was studied with both EDTA-decalcified and undecalcified fresh-frozen cryostat sections. Although the cochleae of the three species are morphologically different, their distributions of proteins, carbohydrates, and lipids are similar. The zona pectinata of the basilar membrane—which is hypertrophied in the kangaroo rat and gerbil but normal in the guinea pig—stains the same in all three species. The unique, flaskshaped Hensen cells of the kangaroo rat contain more protein than do the normal Hensen cells of the gerbil and guinea pig. At least some of the protein in the kangaroo rat Hensen cells is in the form of carboxylic esterases which are not affected by 10^?4 M eserine, but are inhibited by 10^?2 M eserine and 10^?6 M E600. More than one population of carboxylic esterases is indicated by this reaction to inhibitors and by the results of enzyme distribution tests which used different substrates. A high concentration of malate dehydrogenase in the kangaroo rat Hensen cells may be related to the synthesis of carboxylic esterases. The possible role of these esterases in cochlear functioning is discussed.     

Intrafusal fibre types in rat limb muscle spindles: morphological and histochemical characteristics.

Morphological, histochemical and ultrastructural characteristics of intrafusal fibre types were studied in rat muscle spindles. The existence of three intrafusal fibre types, namely the typical bag, the intermediate bag and the chain fibres was confirmed. Intrafusal fibres differ in diameter, length and number of nuclei in the equatorial zone. Histochemically, typical bag fibres exhibit both alkali- and acid-stable ATPase activity and low SDH activity. Intermediate bag fibres possess low alkali-stable ATPase activity; after acid-preincubation, however, they have low activity only in the juxtaequatorial region, whereas in the polar zones they exhibit high acid-stable ATPase activity. The SDH activity varies from moderate to high. The chain fibres exhibit high alkali-stable and low acid-stable ATPase and high SDH activity in the extensor digitorum longus muscle, whereas in the soleus muscle the acid-stable ATPase activity varies from a low one to a high one, either among individual chain fibres in one spindle, and/or repeatedly along the fibre length. Since there are regional differences in morphological characteristics and in staining properties of intrafusal fibres, a reliable identification of intrafusal fibre types can only be achieved by an analysis of serial sections.     

Architectural and histochemical analysis of the semitendinousus muscle in mice,rats, guinea pigs,and rabbits

The architectural and histochemical properties of the anatomically distinct compartments of the semitendinosus muscle (ST) of mice, rats, guinea pigs, and rabbits show that the ST is composed of two separate compartments aligned in series—a destal compartment (STd) and a proximal one (STp). The STp is further subdivided into a ventral head (STpv) and a dorsal head (STpd). The muscle fibers were arranged in parallel to the line of muscle pull within each compartment. The STd has the longest and the STpv the shortest fibers in all species. The physiological cross-sectional area and the estimated tetanic tension was greatest in the STd. Based on the staining pattern for myosin ATPase (alkaline preincubation) and an oxidative indicator (NADH or SDH), the STpv has the highest percentage of slow-oxidative (SO) or SO plus fast-oxidative-glycolytic (FOG) fibers of any portion of the muscle. The differences in fiber-type distributions and architectural designs of the separate compartments suggest a specialization of function of the individual compartments.