K. Unsicker

Immunofluorescence-microscopic demonstration of myosin and actin in salivary glands and exocrine pancreas of the rat.

SummaryActin and myosin were localized in various salivary glands (parotid, submandibular, sublingual, lingual and Harderian gland) and the exocrine pancreas of rats by indirect immunofluorescence microscopy using specific rabbit antibodies against chicken gizzard myosin and actin. A bright immunofluorescent staining with both antibodies was observed at three main sites: (1) In myoepithelial cells of all salivary glands, (2) in secretory gland cells underneath the cell membrane bordering the acinar lumen (except Harderian and mucous lingual gland), and (3) in epithelial cells of the various secretory ducts (of all glands) in similar distribution as in acinar cells. The present immunohistochemical findings in acinar cells could lend further support to a concept suggesting that myosin and actin are involved in the process of transport and exocytosis of secretory granules.

On the innervation of the rat and pig adrenal cortex

SummaryThe innervation of the adrenal cortex of the rat and the pig is investigated with the electron microscope. Nerve fibers containing synaptic and two types of dense-cored vesicles come into contact with endocrine cells. There are no specialized pre- and postsynaptic membranes. The synaptic cleft is about 200 Å wide. Generally the basement membrane between nerve and cell is absent. These observations are discussed on the base of more recent experimental findings. Small fibers having an average diameter of about 0.2 to 0.5 μ and containing only tubules and filaments are considered to represent parts of an afferent nervous system.

Growth characteristics of postnatal rat adrenal medulla in culture

SummaryExplants and enzyme-dispersed cells of adrenal medulla from 10–12 day old rats were studied in culture for up to 3 weeks. Adrenomedullary chromaffin cells, nerve cells and satellite cells were clearly discernible.The nerve cells were few in number and did not show catecholaminespecific fluorescence.Chromaffin cells stored catecholamines, as judged by the Falck and Hillarp method, in varying amounts decreasing with age of the cultures and the distance from the explants. Exocytosis profiles observed with the electron microscope suggested that cultured chromaffin cells also released catecholamines. Moreover, the cells formed processes and frequently migrated into the outgrowth. After 6 days in culture, the great majority of chromaffin cells stored noradrenaline as revealed by electron microscopy with few adrenaline-storing cells being visible. Granular vesicles (∼ 80–240 nm in diameter) with cores of different electron densities were occasionally present in the same cell suggesting the occurrence of mixtures of primary and secondary amines. Apart from “chromaffin” granules, small clear and densecored vesicles (∼ 40–60 nm) were found both in the somata and cell processes. Chromaffin cells and their processes were often closely apposed and occasionally formed specialized attachment zones. As a whole, chromaffin cells in culture resembled small granule-containing cells in sympathetic ganglia.0.5 mM dbcAMP prevented dedifferentiation of chromaffin cells as judged by the lack of processes, the size and amount of “chromaffin” granules and the high number of adrenaline-storing cells present after 6 days in culture.NGF caused a striking increase in the number of axons growing out from expiants.

Fine structure and innervation of the avian adrenal gland

SummaryThe fine structure of the adrenal gland of 15 bird species was investigated by light-, fluorescence-, and electron microscopy as well as by histochemical methods. 1. Adrenal Chromaffin Cells. Cells producing adrenaline (A) and noradrenaline (NA) may be distinguished from each other with the electron microscope by the different structure of their granules. In all species investigated A-cells prevailed. Granules in A-cells of Corvidae, partly those of the other passeriform birds as well, resemble granules from the pituitary pars intermedia because of their incomplete membrane and the low electron density of their contents. A-cells of some passeriform birds have mitochondria with specifically arranged cristae. Large cytosomes and inclusions of lipofuscin pigment are to be found in the gulls Larus ridibundus and Larus argentatus. The House Sparrow (Passer domesticus) and the Chaffinch (Fringilla coelebs) show vacuoles filled with a colloid-like substance, which are surrounded by adrenal chromaffin cells. 2. Ganglion Cells. The adrenal gland of birds is rich in ganglion cells. Two types can be distinguished. “Large” ganglion cells resemble completely sympathetic nerve cells as described in many vertebrates. “Small” ganglion cells have a low nucleus-cytoplasm-ratio. Some of them include granules of various structure and quantity. Whether they represent transitional stages to adrenal cells, interneurons, P-neurons or a heterogeneous population remains to be clarified.

Different types of small granule-containing cells and neurons in the guinea-pig adrenal medulla.

SummaryAn electron microscopic, histoand biochemical study was carried out on the adrenal medulla of newborn and adult guinea-pigs giving special emphasis to small granule-containing (SGC) cells. Adrenaline (A) was the predominating catecholamine (CA) both in newborn (70–90 % of total CA) and adult (85–90%) guinea-pig adrenals. In analogy to the biochemical findings electron microscopy revealed a high predominance of A cells, which contained large granular vesicles with an average diameter of 180 nm. Most noradrenaline (NA) storing cells showed granular vesicles of a considerably smaller average diameter (80 nm) and had a higher nuclear-cytoplasmic ratio. These cells were termed SGC-NA cells. NA cells with large granular vesicles (average diameter 170 nm) were extremely rare. Another type of SGC cells contained granular vesicles with cores of low to medium electron-density (SGC-NA-negative cells). Biochemical determinations made it unlikely that these cells contained predominantly dopamine (DA). SGC cells were scarcely innervated by cholinergic nerves. They formed processes, which were found both in the adrenal cortex and medulla contacting blood vessels including sinusoid capillaries, steroid producing cells of the reticularis and fasciculata zone and processes, which were interpreted to belong to medullary nerve cells.Two types of neurons were present in the guinea-pig adrenal medulla, one resembling the principal neurons in sympathetic ganglia, the other, which, according to its morphology, occupied an intermediate position between principal neurons and SGC cells.In adrenomedullary grafts under the kidney capsule, which were studied three weeks after transplantation, “ordinary” A cells resembled SGC-NA negative cells with respect to their ultramorphology. Processes of transplanted principal neurons showed uptake of 5-hydroxydopamine and, hence, were considered to be adrenergic. Despite the lack of extrinsic nerves to the transplants, few principal neurons received cholinergic synapses, the origin of which is uncertain to date.

Qualitative and quantitative studies on the innervation of the corpus luteum of rat and pig

SummaryQualitative and quantitative studies were made to determine the amount of nerve fiber supplying corpora lutea (CL) of rats during the oestrous cycle and pregnancy and sow CL during days 4–6 after ovulation. Fluorescence microscopy of freeze-dried, paraformaldehyde treated (Falck-Hillarp method) rat ovaries reveals adrenergic nerve fibers which run along with vessels and form a network among interstitial gland cells. Nerve fibers do not enter the granulosa cell layer in follicles or CL. In the CL circumference both vascular and non-vascular nerves occur the latter being related to the fibromuscular layer and probably innervating smooth muscle cells. No striking differences exist between the innervation of the ovary in non-pregnant and pregnant rats. Bodian and methylene blue staining did not contribute to a more detailed knowledge of rat ovary nerve supply. Electron microscopic quantitative analysis of rat and pig CL (rat: day 18 of pregnancy; pig: day 4–6 after ovulation) revealed no axon profiles in 2.000 grid squares (one square measuring 2.25×10-2 mm2) of randomly taken CL sections. Thus it was possible to calculate an upper limit of 133 μm of nerve fibers per 1 mm3 CL tissue, in case there were any at all.

Chromaffin, small granule-containing and ganglion cells in the adrenal gland of reptiles

SummaryChromaffin, small granule-containing (SGC)-cells, neurons and the innervation of these cells was studied in the adrenal gland of three species of reptiles (Testudo graeca, Lacerta dugesi, Natrix natrix). 1.After fixation with glutaraldehyde and osmium-tetroxide adrenaline (A)- and noradrenaline (NA)-storing cells can be distinguished by means of the different electron density of their granules: A-granules are moderately electron-dense, while NA-granules show a core of high electron density. The unusually high electron density of a few A-granules in Testudo occasionally required viewing of unstained sections which facilitated the discrimination of the two cell types in this species. In all species studied NA-granules display a remarkable polymorphism which is most pronounced in the tortoise. In this species A-granules are polymorphic, too. Both types of granules show wide variations in size, which are particularly great in the tortoise. This species also exhibits the largest average sizes for A-granules (285 nm), and NA-granules (354 nm). The corresponding parameters for Lacerta and Natrix, are 255 and 179 nm for A- and 323 and 304 nm for NA-granules, respectively. The rough ER in A- cells of the tortoise regularly occurs in the form of circular dilations (‘ergastosomes’, Kanerva and Hervonen, 1973).Mitochondria sometimes contain longitudinal cristae with a crystalloid internal pattern. Large dense bodies which incorporate granules are abundant in NA-cells. Smaller dense bodies containing a few dense patches and membranes are present in both A- and NA-cells. Intermediate stages between dense bodies and what appear to be A- or NA-granules (if the latter have lost some of their amine-content) are frequently observed.2.Small granule containing (SGC)-cells are regularly found in the adrenal of reptiles. Their granules have an average size of 146 nm in Testudo (188 and 107 nm in Lacerta and Natrix, respectively). The cells exhibit a high nucleo-cytoplasmic ratio and an electron-lucent cytoplasm.3.Various types of nerve cell are present in the reptilian adrenal. Small “light” neurons are similar to SGC-cells, but have only few granules, if any. Large “principal” neurons resemble ganglion cells in various autonomic ganglia. According to the morphology of their nuclei and the amounts and distribution of their ER, they may be divided into “light” and “dark” principal neurons.4.Chromaffin, SGC- and nerve cells are innervated by cholinergic nerve terminals containing small, clear (500–600 Å in diameter) and large, densecored vesicles measuring 730–1340 Å (Testudo). Synapses are usually found on the cell bodies. A-cells in the tortoise which form long processes have their synapses mostly along these processes. A-cell processes are occasionally found in the media of arterioles. Pre- and postsynaptic membrane specialisations are extremely rare on SGC-cells.5.Adrenergic nerve profiles, which are processes of neither chromaffin nor SGC-cells, may be identified after application of 5- and 6-hydroxydopamine in close proximity of chromaffin cells. This paper was presented in part at a Symposium on “Chromaffin, Enterochromaffin and Related Cells” held at Gifu, Japan, 22–24 August, 1975.

On the innervation of mammalian endocrine glands (anterior pituitary and parathyroids)

SummaryElectron microscopic studies have been carried out on the innervation of the mammalian anterior pituitary and parathyroids. The total area of grid squares (2.25·10−2mm2) examined was 2000 per gland and species. In the pituitary pars distalis and in the parenchyma of the parathyroid gland we did not observe a single axon profile. According to the equation

Innervation of the male genital tract and kidney in the amphibia, Xenopus laevis daudin, Rana temporaria L., and Bufo bufo L.

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