Characterization of sodium and pyruvate interactions of the two carrier systems specific of mono- and di- or tricarboxylic acids by renal brush-border membrane vesicles

Summary The experiments reported in this paper aim at characterizing the carboxylic acid transport, the interactions of pyruvate and citrate with their transport sites and specificity. The study of these carriers was performed using isotopic solutes for the influx measurements in brush-border membrane vesicles under zerotrans conditions where the membrane potential was abolished with KCl preloading with valinomycin or equilibrium exchange conditions and =0.Under zerotrans condition and =0, the influence of pyruvate concentrations on its initial rates of transport revealed the existence of two families of pyruvate transport sites, one with a high affinity for pyruvate (K _t =88 m) and a low affinity for sodium (K _t =57.7mm) (site I), the second one with a low affinity for pyruvate (K _t =6.1mm) and a high affinity for sodium (K _t =23.9mm) (site II). The coupling factor [Na]/[pyruvate] stoichiometry were determined at 0.25mm and 8mm pyruvate and estimated at 1.8 for site I, and 3 when the first and the second sites transport simultaneously.Under chemical equilibrium (0) single isotopic labeling, transport kinetics of pyruvate carrier systems have shown a double interaction of pyruvate with the transporter; the sodium/pyruvate stoichiometry also expressed according to a Hill plot representation wasn=1.7. The direct method of measuring Na⁺/pyruvate stoichiometry from double labeling kinetics and isotopic exchange, for a time course, gives an=1.67.Studies of transport specificity, indicate that the absence of inhibition of lactate transport by citrate and the existence of competitive inhibition of lactate and citrate transports by pyruvate leads to the conclusion that the low pyruvate affinity site can be attributed to the citrate carrier (tricarboxylate) and the high pyruvate affinity site to the lactate carrier (monocarboxylate).     

Distribution of a dipeptide naphthylamidase in rat tissues and its localisation by using diazo coupling and labeled antibody techniques

Summary Several rat tissues (liver, spleen, kidney, pancreas, skin, heart, lung and brain) were shown to contain a peptidase capable of liberating naphthylamine from glycyl-dl-proline naphthylamide (Gly-Pro-NA). A single DEAE-cellulose chromatography of autodigested homogenates of the above tissues produced a partial separation of the peptidase from the enzymes hydrolysing l-leucine -naphthylamide. The Gly-Pro-NA hydrolysing enzyme was localised in tissue sections by using diazo coupling reaction and indirect immunologic techniques. Antibodies were prepared against the enzyme purified from rat liver and kidney in the rabbit. Rabbit -globulin was localized by using goat anti-rabbit -globulin labeled with fluorescein or with peroxidase.     

Studies on the neurosecretory system of Iphita limbata Stal.

Summary The present paper gives an account of some experiments upon the insect Iphita limbata Stal. (Hemiptera: Pyrrhocoridae). The experiments were carried out in order to find out whether in the adult animal there is a relationship between the activity of the neurosecretory cells and the water balance. Under varying conditions one group of the neurosecretory cells of the pars intercerebralis of the brain, the so called A-cells, show histological differences. It has been seen that under conditions stimulating hydration there is a marked retention of the stainable colloids in the cytoplasm of A cells. This retention probably indicates a relationship between the secretions of A cells and the water balance of the insect.The author is indebted to Mr. N. R. Prabhoo and Miss Maya Menon of this Department for a critical discussion of the paper.     

Plastommutationen nach R?ntgenbestrahlung vonArabidopsis Thaliana (L) Heynh.

Zusammenfassung Nach Röntgenbestrahlung vonArabidopsis thaliana wurde in der X₁-Generation auf Grund einer intraindividuellen Musteranalyse sowie entsprechender Kreuzungen eine gesicherte Erhöhung der Rate von plasmonisch bedingten Blattfarbveränderungen festgestellt. Bei der Mehrzahl dieser X₁-Pflanzen waren die mutierten, zumeist weißen Gewebe sektorialchimärisch angeordnet; Schecken, wie sie durch eine zufallsgemäße Entmischung erblich verschiedener Plastiden entstehen, fanden sich nur in 8,3% aller Fälle. Verschiedene der induzierten Formen konnten durch einen cytologischen Nachweis von Plastiden-Mischzellen als Plastom-Mutanten identifiziert werden. Insgesamt stieg die Häufigkeit der sicher erwiesenen Fälle von Plasmonabänderungen im Mittel zweier Versuche von einer Spontanrate um max. 0,07 nach Samenbestrahlung auf 1,95 und nach einer Bestrahlung von Zygoten auf 0,95. Damit wurde erstmalig die Möglichkeit aufgezeigt, auchdie Mutationshäufigkeit extrachromosomaler Erbstrukturen durch eine Röntgenbestrahlung zu erhöhen.Mit 5 TextabbildungenHerrn Professor Dr. A.Scheibe zum 60. Geburtstag gewidmet.     

Pump-leak sodium fluxes in low salt corn roots

Summary The influx and efflux of sodium from 4-hr washed, low salt corn roots (Zea mays L.) has been studied for characterization of passive and active components. Initial Na⁺ content of the roots is very low, 2.25±0.4 mol/g fresh weight. Na⁺ influx in the presence of 0.2mm Ca²⁺ and 0.002 to 20mm K⁺ is passive (a leak) based upon Goldman-type models, being determined by Na⁺ and cell potential (). Na⁺ was not transported by the K⁺ carrier and influx was unaffected by 50 m dicyclohexylcarbodiimide (DCCD). Permeability of the cells to Na⁺ was of the same order asP _k.Efflux of Na⁺ was by an efficient and rapid active transport system (a pump), thus accounting for the failure of these roots to accumulate high levels of Na⁺. In short-term loading and efflux experiments, internal Na⁺ turnover had a half-time of about 5 min. Sodium efflux was unaffected by DCCD. Net H⁺ flux was zero in the presence of DCCD regardless of sodium efflux, indicating absence of Na⁺/H⁺ antiport. Efflux of Na⁺ was equally rapid into medium containing no Na⁺ and only 0.002mm K⁺. K⁺ influx accounted for less than 4% of Na⁺ efflux, prompting the hypothesis that the Na⁺ (or cation?) efflux pump is the second electrogenic system previously defined based upon electrophysiological measurements.     

The neurosecretory system of the adult Calliphora erythrocephala

Summary Neurosecretory cells in the brain and suboesophageal ganglion of the adult female Calliphora erythrocephala have been studied in the light microscope. The paraldehydefuchsin stain (PAF) gave by far the clearest pictures.The medial neurosecretory cells of the protocerebrum (m.n.c.) show definite cyclic changes as to the size of the nuclei and the content of secretory material. The cytological changes depend on the age of the fly and the diet given and are correlated with ovarian development.The nuclear size is held to express the metabolic activity of the cells. Cells with large nuclei, as found in young sugar-flies (S1D) and meat-fed flies with developing ovaries (S4D/M2D), contain less secretory material which is released through the axons, while the m.n.c. of old sugar-flies (S6D) have small nuclei and are stuffed with secretory material which is stored in the perikarya.These results confirm those obtained by darkfield microscopy of living m.n.c. by Lea and E.Thomsen (1962 and unpublished).No really convincing evidence for the existence of more than one type of m.n.c. was found.Two small groups of lateral cells were observed. Possibly neurosecretory are further: 1-(2) cells at the base of each optic lobe, two groups of 2–3 cells on the caudal side of the brain, and 2 cells ventrally in the suboesophageal ganglion.Giant neurons of unknown function are situated very near the m.n.c. Their axons join those from the m.n.c., but end in the suboesophageal ganglion.The same region comprises a number of peculiar cells, each containing a large, fluid-filled vacuole (the vacuolated cells). Similar cells are associated with the possibly neurosecretory cells on the caudal side of the brain.My sincere thanks are due to my wife Dr. Ellen Thomsen, who made all the excisions of the brains and the measurements of the nuclei, to T.C.Normann for valuable assistance with the photographic work, and to Mrs. K. Bahnert for technical help with the gallocyanin method. The Carlsberg Foundation has supported the work with grants.     

Über die „Stipeln“ vonRhytidophyllum Mart. (Gesneriaceae)

Zusammenfassung Die vielfach als Stipeln angesprochenen basalen Blattanhänge einiger Taxa der GesneriaceengattungRhytidophyllum Mart. können nicht als solche gelten, da ihnen wesentliche Merkmale echter Stipeln fehlen, insbesondere konstante Ausbildung bzw. Auftreten in der Blattfolge, praekursive Anlegung und proleptische Entwicklung. Gleichwohl sind sie aber als Bildungen des Blattgrundes zu betrachten und daher als vaginale Öhrchen im Sinne vonWeberling zu bezeichnen. Die bei manchen Taxa auftretenden sitzenden Laubblätter mit verbreiterter, teilweise stengelumfassender Blattbasis werden durch laubige Verbindung von Blattspreite und Öhrchen erklärt.Infolge Fehlens echter Stipeln bildet somitRhytidophyllum keine Ausnahme hinsichtlich der Blattgestaltung unter den Tubifloren.

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About the stipules ofRhytidophyllum Mart. (Gesneriaceae)

Summary The foliar appendages at the base of the short petiole in some taxa ofRhytidophyllum are often called stipules. But this term is not applicable, because these appendages lack important characteristics of true stipules, f. i. constancy in form and appearence during leaf succession, early ontogenetic origin and prolepsis. Nevertheless they are effigurations of the leaf base (Unterblatt) and have therefore to be regarded as vaginal auricules in the sense ofWeberling. The sessile and partially sheating leaves in someRhytidophyllum taxa result from foliar connections between lamina and auricules.Because of the absence of true stipulesRhytidophyllum fits well into the general leaf morphology of Tubiflorae.

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Herrn Prof. Dr. W.Leinfellner und Herrn Prof. Dr. F.Ehrendorfer danke ich für die Durchsicht des Manuskripts.     

Plant regeneration in weeping lovegrass, (Eragrostis curvula) through inflorescence culture

Plant regeneration from four genotypes of weeping lovegrass (Eragrostis curvula (Schrad.) Nees), is reported via three developmental pathways: embryogenesis, organogenesis and direct regeneration. Organogenic and embryogenic callus cultures were initiated from young inflorescence segments on Murashige and Skoog's medium supplemented with 2,4-d and BA at different concentrations. The most suitable concentrations of 2,4-d for callus growth and development were 9 and 18 M combined with a BA concentration of 0.044 M. Genotypical differences were observed in the morphogenetic capacity. Direct regeneration was observed under similar culture conditions (culture medium, temperature and photoperiod) but with high light intensity (66 mol m^-2 s^-1). Young plants were successfully transplanted to pots and grown to maturity in the greenhouse.Abbreviations BA benzyladenine - 2,4-d 2,4-dichlorophenoxyacetic acid - MS Murashige and Skoog medium - NAA naphthaleneacetic acid     

Über die Ultrastruktur des „Nervus opticus“ und des Ganglion opticum I von Daphnia pulex

Zusammenfassung Die Opticusfasern (Neuriten der Rezeptorzellen) und das Ganglion opticum I von Daphnia pulex wurden elektronenmikroskopisch untersucht. Die 8 Neuriten jeweils eines Ommatidiums werden in einem Bündel zusammengefaßt, in dem die Neuriten nur unvollständig von einem Gliafortsatz umhüllt sind, das Bündel jedoch vollständig von einer Basalmembran bedeckt ist. Die Neuriten weisen quervernetzte Mikrotubuli auf. In der Peripherie des Ganglion opticum liegen große und kleine unipolare Nervenzellen, deren Fortsätze ins zentrale Neuropil ziehen, wo sie u.a. synaptische Kontakte mit den Neuriten bilden. Es werden 3 Formen von Synapsen beschrieben: 1. eine bisher nicht beschriebene Synapsenform, 2. Synapsen von gewöhnlichem Typ und 3. Ribbon Synapsen. Die peripher gelegenen Gliazellen umhüllen die Nervenzellen und senden lamelläre Fortsätze in das Neuropil, wo sie sich den benachbarten Zellelementen derart anpassen, daß der extrazelluläre Raum zu einem System von Interzellularfugen eingeengt wird. Außer den beschriebenen Zellformen kommen weniger häufig neurosekretorische Nervenzellen vor, deren Fortsätze an der Ganglionoberfläche nur von Basalmembranen bedeckt sind. Ferner sind selten multipolare Ganglienzellen zu finden.

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On the ultrastructure of the optic nerve and the ganglion opticum I of Daphnia pulex

Summary Optical fibres (neurites of receptor cells) and ganglion opticum I of Daphnia pulex were studied electron microscopically. The 8 neurites of each ommatidium are bundled by a complete wrapping of basement membrane, while each neurite is incompletely enveloped by a glial process. The neurites contain transversally interconnected microtubules. Processes of large and small unipolar nerve cells situated at the periphery of the ganglion reach the central neuropile, where they establish synaptic contacts, f.i., with optical fibres. 3 types of synapses occur: 1. one type of synapse which has not yet been described, 2. synapses of the usual type, 3. ribbon synapses. Glial cells situated peripherally in the ganglion envelope the nerve cells. Their lamellar processes projecting into the neuropile adapt their surfaces to all neighboring elements so that the extracellular space is reduced to a labyrinth of narrow intercellular clefts. The number of multipolar ganglion cells and neurosecretory elements is relatively small. The processes of neurosecretory cells contact the surface of the ganglion where they are covered by a basement membrane.

     

Cells with microvillous borders in the cerebral ganglion of Leptodora kindtii focke (Crustacea)

Summary Groups of large cells in the cerebral ganglion of Leptodora kindtii join in intricate patterns to enclose lacunar spaces. The cell surfaces bordering on these lacunae are covered by long, densely packed microvilli that all but fill the spaces. Near their brush borders the cells are joined by adhesion plates; for the rest they are separated from each other by glial septa. The possible significance of these structures is discussed.Dedicated to an inspiring teacher and loyal friend, Prof. F. Wassermann on the occasion of his 80th birthday, August 13, 1964.Supported by Grant No. NB-02145 from the United States Public Health Service. The expert assistance of Mrs. Cynthia Jones, Mrs. Sarah Wurzelmann, and Mr. Stanley Brown is gratefully acknowledged.     

Cytological and molecular observations on Solanum phureja-induced dihaploid potatoes

Summary Seventeen potato dihaploids, produced by pollinating the tetraploid (2n = 48) cv Pentland Crown with pollen from Solanum phureja (2n = 24) dihaploid inducer clones, were studied. Since dihaploids are thought to develop parthenogenetically from unfertilized ovules they were expected to be euploid (2n = 24), but somatic chromosome counts showed that 15 of the 17 dihaploids were aneusomatic. Ten of the clones were predominantly diploid (2n = 24) with a proportion of hyperploid cells that contained 25 or 26 chromosomes. Five of the dihaploids contained variable numbers of triploid cells (2n = 36). RFLP analysis was used to determine whether the additional chromosomes were from S. phureja or S. tuberosum. Unique hybridizing fragments present in S. phureja but not in Pentland Crown were identified. These S. phureja-specific restriction fragments were present in some of the dihaploid offspring of Pentland Crown. Of the 5 clones that contained triploid cells 4 had S. phureja type banding. Four of the 10 aneusomatic clones that contained hyperploid cells had the unique S. phureja hybridizing fragments. We propose that ovules of Pentland Crown were fertilized by pollen from S. phureja and that the aneusomatic clones were derived from triploid zygotes from which some of the S. phureja chromosomes were eliminated. We consider that this is an additional mechanism of dihaploid formation in potato.     

“Natural” Antibodies to chicken MHC antigens are present in mice,rats, humans,alligators and allogeneic chickens

In the absence of any deliberate immunization, mice, rats, humans and alligators all have detectable titers of antibody against chicken red blood cells (CRBC's). Remarkably, this antibody is directed predominantly against private or public determinants of MHC proteins on the CRBC's, and little or no antibody is directed against species-specific determinants on MHC or other proteins, including other polymorphic blood group antigens. In chickens, natural antibody can be detected against CRBC's from all chickens differing at the MHC locus, but natural antibodies against other polymorphic antigens are not detected. Using a rosette-forming cell (RFC) assay, we have also shown that a large percentage of mouse spleen cells will rosette with chicken erythrocytes, and that the majority of these RFC's also recognize polymorphic antigens.     

Immunohistochemical localization of opioid peptides in the brain of the leech Theromyzon tessulatum

Summary By use of antisera directed against met-enkephalin, leu-enkephalin, dynorphin or -neoendorphin, immunoreactive structures were visualized in the central nervous system and proboscis of the leech Theromyzon tessulatum. Their distribution in the various compartments of the supra- and subesophageal ganglia was mapped. No correspondence could be established between the neurons containing met- or leu-enkephalin-like substances and the different types of neurosecretory cells classically described in Hirudinea. Successive localization of leu- and met-enkephalin on the same section revealed that these two peptides occur in different neurons. Only one cell located in compartment 6 of the supraesophageal ganglion was both dynorphin- and leu-enkephalin-positive. The other dynorphinimmunoreactive cells were not stained with the anti-leuenkephalin serum. The -neoendorphin-immunopositive cells were leu-enkephalin immunonegative and vice versa.     

Physiological and anatomical properties of Leydig cells in the segmental nervous system of the leech

Summary Each of the 21 segmental ganglia in the American leechMacrobdella decora contains a pair of Leydig cells (ca. 45 m) each of which is located in a posteriolateral glial packet. Leydig cells exhibit spontaneous action potentials (1–10/s) whose duration and undershoot depend upon membrane polarization. The two Leydig cells within each ganglion are bidirectionally-coupled (V ₂/V ₁0.3). Pairs of ipsilateral Leydig cells within adjacent ganglia are mutually excitatory such that an impulse in one generates an impulse in the other. The interganglionic latency for any cell pair is constant regardless of the direction of impulse conduction and is unchanged by 20 mM Mg²⁺ saline. These data indicate that the interactions are not mediated by chemical synapses. Additionally, the results of collision experiments lead us to infer that ipsilateral Leydig cell pairs utilize common axonal pathways for interganglionic interactions. If Leydig cells are driven by current injection to fire impulses at frequencies of six to ten per s, cells in adjacent ganglia exhibit impulse failures. The combination of spontaneous activity, intraganglionic coupling and interganglionic interactions results in the generation of constant, low frequency impulse activity and can cause impulse reverberations.The branching pattern of Leydig cells filled with HRP is consistent with their functional properties and connectivity. Each cell sends axons to both adjacent ganglia through the ipsilateral connectives and projects to the periphery only by the lateral roots of these adjacent ganglia. This unusual morphology was verified Lucifer Yellow CH.In addition to intraganglionic dye-coupling, dye coupling was occasionally evident between ipsilateral cells in adjacent ganglia. Electron microscopy of Leydig cells depicts abundant 100 nm granules in both their somata and neuropilar processes. Although this fine structure suggests a neurosecretory role, we were unable to discern a peripheral function for these neurons.Abbreviation H R P horseradish peroxidase     

Weitere elektronenmikroskopische Untersuchungen am kaudalen neurosekretorischen System von Fischen

Zusammenfassung Das kaudale neurosekretorische System von Cyprinus carpio und Channa argus Cantor wurde elektronenmikroskopisch untersucht. Während in den Golgi-Bläschen von Channa nur eine Art von Elementargranula entsteht, kommen bei Cyprinus zwei Granulatypen verschiedener Größe und Elektronendichte (- und ß-Granula) vor, jedoch nie in ein und derselben neurosekretorischen Zelle zusammen. Bei Cyprinus werden Elementargranula verschiedener Elektronendichte aus der Zelle in die perivaskulären Räume abgegeben.Außer Elementargranula wurden große Tropfen mit verschiedener Struktur in den Perikaryen und in den Basen der Zell-Fortsätze beobachtet. Ein Teil der Tropfen ist durch Verschmelzung der Elementargranula entstanden, die meisten jedoch entsprechen Lysosomen, Myelinfiguren, multivesicular bodies usw.Die neurosekretorischen Zellen sind durch zahlreiche axo-somatische und axo-axonale sowie axo-dendritische Synapsen mit nichtsekretorischen Nervenzellen verbunden. — Da die Wandungen der endozellulären Kapillaren ohne Zwischenschaltung einer gliösen Schranke die Zellmembran der Perikaryen berühren, wird ein unmittelbarer Stoffaustausch zwischen neurosekretorischen Zellen und Blut vermutet.

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Summary The caudal neurosecretory system of Cyprinus carpio and Channa argus Cantor was studied electron microscopically. In the secretory nerve cells of both species the elementary granules are formed in the Golgi complex. In the neurosecretory system of Cyprinus carpio two kinds of neurosecretory cells can be differentiated according to the size and the electron density of their granules (- and ß-granule). Grnules of both types cannot be found in the same neurosecretory cell. In Cyprinus the elementary granules of various density are released into the pericapillary space.Apart from the elementary granules droplets with various structures in the perikarya and bases of the processes were recognized. A part of these droplets consists of accumulated elementary granules, the majority however belongs to inclusions like lysosomes, myelinfigures, multivesicular bodies and so on.The neurosecretory elements are connected with non-secreting nerve cells by numerous axo-somatic, axo-axonic and axo-dendritic synapses. In Channa argus the perikarya of neurosecretory cells are in close contact with the basement membrane of the capillary, i.e. there is no glial barrier between the neurosecretory cell and the blood vessel.

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Frau Professor Dr. B. Scharrer zum 60. Geburtstag gewidmet.     

Effect of 20-hydroxyecdysone on neurosecretory cell activity in femaleHyalomma dromedarii synganglion (Acari: Ixodidae)

Twentyg of 20-hydroxyecdysone (20-he) were applied topically to nymphalHyalomma dromedarii Koch on the day of detachment. In emerging adult females, some neurosecretory cells (nsc) in certain synganglion centers exhibited changes in size and/or neurosecretory material (nsm) shape, distribution and/or quantity. These changes were compared with those normally occurring in untreated unfed, semifed virgin and mated, and engorged females. 20-he effects included (a) accelerating the changes induced by mating and/or feeding in certainnsc, (b) reducing, to various extents,nsc response to mating and feeding, and (c) inducing changes in somensc which do not normally exhibit any changes in untreated females. The results suggest that (a) most femalensc respond more or less similarly to indigenous 20-he, (b) 20-he may have a role as a positive feedback regulator fornsm synthesis and/or release by certainnsc, (c) the response to 20-he may be primarily a function ofnsc location in the synganglion, and/or (d)nsc considered to be of one type may actually belong to different cell types.     

Gonoid thelytoky in soft scale insects (Coccidae: Homoptera)

Cytological analysis of the thelytokous soft-scale insects Coccus hesperidum L. (2n=14) and Saissetia coffeae (Walker) (2n=16) revealed that while in both species the chromosomes did not pair during prophase I, meiosis consisted of two divisions, the chromosome number was reduced, and diploidy was restored by the fusion of the female pronucleus with the polar nucleus II. The difficulty of trying to classify this type of thelytoky as either automictic or apomictic led to the proposal that a new criterion and new terms be used to classify thelytoky (and parthenogenesis). The new criterion is whether the number of chromosome elements present in the first (or only) metaphase of oogenesis is the same as that present in the oogonia (gonoid thelytoky) or different from it (agonoid thelytoky). The new criterion is superior to the existing criteria because it is unambiguous, and because it groups together forms with a similar tendency towards heterozygosity (or homozygosity). The possible evolution of the forms analyzed as well as the two other thelytokous forms of each species described by Thomsen (1927) are discussed. Another soft-scale insect, Physokermes hemicryphus Dalam, consisted of a diploid (2n=18) and a triploid (3n=27) form, in both of which the chromosomes also did not pair. Each of the three species contained a strain in which only a single nucleolus was present per cell. In C. hesperidum some strains with two nucleoli differed in the size of the nucleoli.     

Some remarks to the Sterba's Fluorescent method in application to the neurosecretory cells

Summary When staining the neurosecretory cells with N,N-diethylpseudoisocyanine chloride according to Sterba fluorescence of nucleolus and structures in the peripheral zone of the cytoplasm was observed simultaneously with the fluorescence of the neurosecretory granules. Preliminary treatment of sections with ribonuclease made it possible to obtain preparations in which only neurosecretory granules fluoresce in the neurosecretory cells. It proves that the secondary fluorescence of the peripheral structures is due to the ribonucleic acid they contain, and the structures themselves are Nissl's substance. The intensity of the secondary fluorescence of the neurosecretory substance and the Nissl's substance changes when embedding sections stained with N,N-diethylpseudoisocyanine chloride in media with different pH values (from 2.6–8.9), these changes being different for each of these components. The most striking contrast between the fluorescence of the neurosecretory substance and the rest of the structures of the cell was observed in the pH 4.0–4.9 region. Especially stable preparations can be obtained by using a stain diluted with a buffer with pH about 4.5. The proposed modification of the method makes it possible to obtain preparations with more striking electivity of the secondary fluorescence of the neurosecretory substance than when using original method of Sterba.     

Über die Morphologie der Milch sekretion. II Zugleich eine Kritik am Schema der Sekretionsmorphologie

Summary p]1.|An electron-microscopical study of the mammary gland of lactating mice and golden hamsters was carried out in order to obtain new evidence on the secretion of milk and to understand some discrepancies between earlier findings of Bargmann and Knoop (1959) in rats and of Hollmann (1959) in mice.In both species, mice and golden hamsters, the results on the formation and extrusion of the protein particles are similar to those previously obtained in the rat. The protein particles are formed in Golgi vacuoles, which are transported to the luminar side of the cell. The content of these vacuoles is discharged into the acinar lumen.Within the Golgi vacuoles containing protein particles there is always a considerable amount of seemingly empty space; in addition, there is some accumulation of extremely fine coagulated material. When discharged, these coagulations are believed to constitute part of the milk plasm. The formation of fat droplets was invariably found to be related to the ergastoplasm and not to the Golgi apparatus. In mice as well as in golden hamsters the fat droplets are transported to the apical part of the cell, where they protrude the plasmamembrane into the lumen. Eventually, each fat droplet is pinched off with a thin cytoplasmic envelope, the so called fat droplet membrane. Release of droplets by rupture of the plasmamembrane, as described by Hollmann (1959) in mice, was not seen in our material and is believed to be due to an artifact.In the lactating golden hamster mammary gland cells, big fat droplets sometimes deeply indent the nuclear membrane from the cytoplasmic side, thus giving rise in some sectional planes to the misleading impression of big nuclear inclusions. Apart from these droplets, which are always surrounded by the nuclear membrane, sections of the glandular cell nuclei often show a number of smaller fat droplets which are not surrounded by a membrane. These small and inconspicuous droplets are believed to be true nuclear inclusions.During lactation the glandular cells are provided with numerous microvilli; in the golden hamster there are roughly 10–20, and in the mouse about 25 microvilli per square . The increase in cell surface brought about by the microvilli is thought to be related to resorptive processes which were first suggested by Grynfeltt (1937) and proved to exist by Azimov (1959). p]2.|The electron-microscopical findings on the secretion of milk as well as findings on other types of glandular cells are discussed in a broader frame with respect to their bearing on the systematics of secretion in general. It is shown that the term apocrine secretion can no longer be retained. In accordance with the classical concept of Ranvier, glands should be subdivided into two groups only. In the one group, the glandular cells survive the formation of their secretory products, whereas in the other group the cytoplasm of the glandular cells is completely exhausted so that the cells cannot survive more than one secretory cycle. The terms merocrine and holocrine may be appropriate, but one must be aware of the fact that the essential features of the formation of secretory products in holocrine glands are not entirely different from those in other types of glands and that the term degeneration is misleading when used in this connection.

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Durchgeführt mit Unterstützung durch die Deutsche Forschungsgemeinschaft.

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Herrn Prof. Dr. Mothes, dem Präsidenten der Deutschen Akademie der Naturforscher Leopoldina, zum 60. Geburtstag gewidmet.     

Electron microscopical and histochemical observations on the relation between medio-dorsal bodies and neurosecretory cells in the basommatophoran snails Lymnaea stagnalis,Ancylus fluviatilis,Australorbis glabratus and Planorbarius corneus

Summary In Basommatophora medio-dorsal bodies (MDB) are closely attached to the cerebral ganglia, in which, just underneath the bodies, groups of Gomori-positive neurosecretory cells (MDC) occur. It has been suggested that the MDB-cerebral ganglion complex should be regarded as a neuro-endocrine association.In the present study the morphological relation between MDB and the ganglion is histochemically and ultrastructurally investigated in Lymnaea stagnalis, Ancylus fluviatilis, Australorbis glabratus and Planorbarius corneus.Histochemical tests showed the paraldehyde-fuchsin positive material of fibers in the MDB to be different from the neurosecretory material (NSM) in the MDC. At the ultrastructural level no penetration of nerve cell processes through the perineurium, separating the MDB from the ganglion, into the medulla of the MDB was observed. However, excepting for Lymnaea, the perineurium at these places shows particular differentiations. In the medulla of the MDB granule laden profiles (granule ø 700–900 Å) occur. They appeared to be processes of MDB cells.From these results it is concluded that the medulla of the MDB should not be regarded as a neurosecretory neuropile. Apparently, the MDB-cerebral ganglion complex is no neuroendocrine association. Probably the MDB is an endocrine organ. The small electron dense granules of the profiles in the medulla were also found in the MDB cell bodies. They are thought to represent a secretion product. The close morphological relation between MDB and cerebral ganglion may be connected with the origin of the MDB cells from perineural elements.