Demonstration of ATPase activity in skeletal muscle fibers of the triceps muscle of arm in white rats during development

On the base of modified calcium and method from Zebe and Falk (1964) for demonstration of ATPase activity results at the long head of the triceps muscle of white rats aged 1, 3, 6 weeks and 3 month were shown. This method is proper to make visible alteration of the localisation of the reaction product during the postnatal development. Further investigations are necessary in order to correlate the steps of differentiation of muscle fibres with the strength of ATPase activity.     

Light and electron microscopic studies of nucleus-like formations of fragmented oocytes in rat ovary]

Oocytes in ovarian atretic follicles now and then show in their cytoplasm nucleuslike formations. The appearance of those pseudonuclei in the rat is described by light-and electron microscopy. Every pseudonucleus contains one or more Feulgen positive particles, and is surrounded by a membrane on its surface. The pseudonuclei are formed in the course of degeration of the oocyte during 1. und 2. meiotic metaphase from contracted chromosomes, probably with the involvement of the mixoplasma.     

Afferent nerve endings in the small intestine and the stomach. Light and electron microscopic studies]

1. In the mucous membrane of the duodenum and pylorus there have been identified free club- and tree like endings by ligth and electron microscopy. These endings lie flat between the muscularis mucosae and the glandular basis. 2. In the duodenum of the dog the receptors are undoubtly formed by myelinated axons. 3. According to neurophysiological results these free afferent endings are similar to PAINTAL'S (1957, 1963) mucosal mechanoreceptors.     

Light and electron microscopic studies on capillaries of the goat cardiac muscle with special reference to the topographical relationship between the vessels and Purkinje fibers

The capillaries of the cardiac muscle were investigated in the goat by means of light microscopy, transmission electron microscopy and scanning electron microscopy, and the following results were obtained. The capillaries of the working cardiac muscles were numerous, arranged mainly parallel to the long axis of muscle cells and formed dense elongated networks. On the contrary, those of the terminal Purkinje fibers were relatively few in number, oriented in various directions and formed loose and circularly meshed networks surrounding the fibers. Such findings were discussed in correlation with the physiology and functional morphology of various types of the cardiac muscle cells.     

Light and electron microscopic studies of the ventricular wall

Summary Electron microscopic data confirm the results gained with rapid Golgi preparations of adult rodent brains that tanycytes occur in clusters along the lateral wall of the third ventricle. The cytoplasmic matrix of these cells is considerably denser than that of typical ependymal cells. They have filaments and microtubules throughout their cytoplasm along with mitochondria and polysomes. At the surface is a compact group of microvilli which suggest that tanycytes might selectively absorb material from the ventricle.The tanycytes are segregated from neuropil by other tanycyte processes, by neighboring ependymal cells and by astrocytes. Yet there are gaps in this sheath. At these points tanycytes either abut upon or surround nonglial components of the neural fabric.Their cytological features and relations with the neuropil suggest that tanycytes selectively absorb material from the ventricle and release it along the basal process, primarily affecting those segments of neurons immediately adjacent to the tanycyte.Supported by: NINDS Grants 5 R01 NS 09001-02 NEUA, 5T01 NB 5309, and GM 00958, and by the Eleanor Roosevelt Cancer Foundation Research Institute.Acknowledgements: This work was initiated in the Anatomy Department of the Harvard Medical School with facilities provided by Prof. S. L. Palay (U.S. Public Health Service Grant No. NB 05591). Dr. R. B. Wuerker kindly and patiently provided the instruction and orientation to electron microscopy. The major portion of the study was completed in the Neurology Department of the University of Utah with the extremely competent, challenging assistance of Dee Lerdahl, Nina Belgarian, Keith Johnson and Lynn Kendricks.     

Cholinesterase activity of capillaries in the rat brain. A light and electron microscopic study

Synopsis The presence of cholinesterase activity in association with capillaries of the central nervous system was investigated in the rat by means of both light and electron microscopic methods. Throughout most of the rat brain, the smaller blood vessels stain intensely for butyrylcholinesterase activity. In some areas, such as the commissural nucleus of the vagus and parts of the medial thalamus, the capillaries possess both acetylcholinesterase and butyrylcholinesterase activity. Blood vessels in those structures which lie outside the blood-brain barrier are completely devoid of cholinesterase activity. The electron microscope reveals that reaction product occurs within the matrix of the basement membrane, in the intermembranous space of the endothelial nuclear envelope and occasionally in the endothelial granular endoplasmic reticulum. It is suggested that the presence of cholinesterase within the basement membrane of brain capillaries is evidence of the role that the basement membrane may play in transfer mechanisms.     

Light and electron microscopic studies of crayfish hemocytes

Using light and electron microscopy, three hemocyte types are described in the hemolymph of the crayfish. The coagulocyte comprises 65% of the total hemocyte number and contains medium-sized cytoplasmic granules, abundant dilated rough endoplasmic reticulum, and a highly developed Golgi complex. It rapidly undergoes cytolysis in vitro and participates in coagulation by releasing the contents of its granules to the hemolymph. The granulocyte comprises 31% of the total hemocyte number and is capable of phagocytosis. It contains large, irregularly shaped cytoplasmic granules, a moderately developed Golgi complex, and moderate amounts of non-dilated rough endoplasmic reticulum. During coagulation in vitro, the cell attaches and spreads onto the substratum; this is followed by a slow intracellular granule breakdown and cytolysis. The amebocyte comprises 4% of the total hemocyte number and it is also capable of phagocytosis. It possesses small cytoplasmic granules, many vacuoles, a moderately developed Golgi complex, and large amounts of smooth endoplasmic reticulum. It is distinguished from the other two cell types by being stable and motile in vitro.     

Light and electron microscopic studies on the localization of hyaluronic acid in developing rat cerebellum

The hyaluronic acid-binding region was prepared by trypsin digestion of chondroitin sulfate proteoglycan aggregate from the Swarm rat chondrosarcoma, and biotinylated in the presence of hyaluronic acid and link protein. After isolation by gel filtration and HPLC in 4 M guanidine HCl, the biotinylated hyaluronic acid-binding region was used, in conjunction with avidin-peroxidase, as a specific probe for the light and electron microscopic localization of hyaluronic acid in developing and mature rat cerebellum. At 1 w postnatal, there is strong staining of extracellular hyaluronic acid in the presumptive white matter, in the internal granule cell layer, and as a dense band at the base of the molecular layer, surrounding the parallel fibers. This staining moves progressively towards the pial surface during the second postnatal week, and extracellular staining remains predominant through postnatal week three. In adult brain, there is no significant extracellular staining of hyaluronic acid, which is most apparent in the granule cell cytoplasm, and intra-axonally in parallel fibers and some myelinated axons. The white matter is also unstained in adult brain, and no staining was seen in Purkinje cell bodies or dendrites at any age. The localization of hyaluronic acid and its developmental changes are very similar to that previously found in immunocytochemical studies of the chondroitin sulfate proteoglycan in nervous tissue (Aquino, D. A., R. U. Margolis, and R. K. Margolis. 1984. J. Cell Biol. 99:1117-1129; Aquino, D. A., R. U. Margolis, and R. K. Margolis. J. Cell Biol. 99:1130-1139), and to recent results from studies using monoclonal antibodies to the hyaluronic acid-binding region and link protein. The presence of brain hyaluronic acid in the form of aggregates with chondroitin sulfate proteoglycans would be consistent with their similar localizations and coordinate developmental changes.     

An electron microscopic study of the development of rat testis in the first 10 postnatal days

Summary The ultrastructure of testis of immature rats from birth to ten postnatal days was studied in order to describe the development of germ cells into definitive spermatogonia. The primordial germ cells showed no structural changes from birth to 4 days after birth. At the 5th postnatal day the gonocytes were transformed into darker cells and began to migrate towards the basement membrane. As they reached the periphery of the seminiferous cords they resumed mitoses and gave rise to smaller gonocytes, which were progressively transformed in definitive spermatogonia. A lighter kind of supporting cell was also detected.We wish to thank Mrs. L. Giaccardo, A. Pozzolini and E. Taccini for skilled technical assistance.From the Department of Medical Pathology, Pisa University, Pisa, Italia.     

Light and scanning electron microscopic studies of flower development inLindenbergia macrostachya Benth. (Scrophulariaceae)

All the floral primordia are homologous to leaves in their development inLindenbergia macrostachya. The sepals follow an anterior to posterior sequence of initiation. The petals and stamens are initiated almost simultaneously but sequentially in order of petals followed by stamens. There is no sign of development of fifth posterior stamen. p ]The calyx tube is formed by interprimordial growth followed by zonal growth. The combined interprimordial growth between the petal primordia and growth on the abaxial side of stamen primordia results in the formation of upper corolla tube whereas lower corolla tube is formed only by zonal growth. The zonal growth extends below the bases of stamen primordia also due to which they become epipetalous. The placentae arise from the carpellary margins, move inwards and get fused in the lower half and remain free in the upper part of the ovary. Thus the ovary appears biloeular with axile plaeentation in the lower haler and unilocular with parietal placentation in the upper half.     

Interpretation of the cross sectional structure of skeletal muscle fibers. 2. Light and electron microscopic studies of m. rectus abdominis in Rana esculenta]

In both longitudinal and cross sections of rectus abdominis muscle of Rana esculenta three types of muscle fibres are identified by means of light and electron microscopy. A comparison is made between these fibre types in homologous muscles of frog and mammals (rat and mouse). In longitudinal sections of mammalian and frog muscle the Z-line can be used for discrimination of the fibre types A, B and C because that line is of different thickness in each type. The proportions of the thickness in frog and mammalian muscles are relatively the same, but the absolute values are different. In cross sections there are no differences between frog and mammalian muscle fibres concerning the typical form of myofibrils in type A- and B-fibres, whereas in type C-fibres the arrangement of the filaments in the Z- and H-layer is different in the members of both animal classes. The amount of mitochondria and lipid droplets is different as well. In the species examined the distribution of A-, B- and C-fibres changes within the whole muscle. In frog, this pattern depends on the level in which the muscle has been sectioned. This is not true for mammalian muscle. On the other hand both ends of the rectus abdominis muscle in frog, rat and mouse show an accumulation of B- and C-type fibres.