Ultrastructural studies on the nucleoli of the follicle cells in the Lizards Acanthodactylus scutellatus hardyi and Eremias brevirostris

Summary In male mice homozygous for both p ^s and hpy, two recessive, pleiotrophic, mutations, gametogenesis is normal through meiosis but no functional spermatozoa are produced. Spermiogenesis is abnormal from the Golgi phase on. The types of abnormalities seen during the early and mid-stages of Spermiogenesis are characteristic of those associated with the presence of the p ^s mutation whereas those associated with the hpy mutation appear during the later stages of spermatid development. While centriolar ultrastructure was normal, axonemal structures were only rarely encountered and no late spermatids with recognizable flagella were seen. Some late spermatids showed head abnormalities of the type characteristic of the p^s mutation while others were recognizable as being of the hpy type. A released gamete usually consisted of a distorted nucleus and associated acrosome enclosed in a tightly fitting plasma membrane. No spermatids exhibiting a novel phenotype were encountered. The findings support the view that, despite their simultaneous presence in the double homozygote, each mutation acts autonomously. These studies also allow a similar inference to be made with respect to the extent of the interrelationship of the other major sub-processes of Spermiogenesis.The author wishes to express his thanks to Mr. Clifford S. Shuman III for capable technical assistance     

Relationship between the chromatoid body and the acrosomal system in early spermatids of Myxine glutinosa L.

Summary A transient close relationship between the chromatoid body and the developing acrosome is demonstrated in early spermatids of Myxine glutinosa.This work was supported by the Norwegian Research Council for Science and Humanities (NAVF, Grant Nr. D 61.44) and the Austrian Fonds zur Förderung der wissenschaftlichen Forschung, Projekt 2183     

Functional analysis of a complex oncogene arrangement in biotype III Agrobacterium tumefaciens strains

The ubiquitous grapevine-associated octopine/cucumopine Ti plasmids of biotype III Agrobacterium tumefaciens strains carry two T regions, TA and TB, with a complex oncogene arrangement. Within the octopine/cucumopine group, two main strain types were identified: large TA strains with a TA region resembling the TL region of the biotype I octopine strain Ach5 and small TA strains with a similar T region organization as the large TA strains but with a large internal TA deletion. Structural and functional studies of the representative large TA strain Tm4 revealed six oncogenes. Each oncogene was inserted in a disarmed vector and tested for biological activity using the corresponding oncogenes of Ach5 as standards. Five Tm4 oncogenes, TA-iaaM, T-ipt, T-6b, TB-iaaH and TB-iaaM, were shown to be active, the IS-interrupted TA-iaaH gene was inactive. To study the role of each gene in the pTiTm4 context, several single and multiple pTiTm4 mutations were constructed. It was shown that whereas TA-iaaM and TB-iaaH are essential for tumour formation on grapevine, T-ipt, T-6b and TB-iaaM are not. The avirulence of the TA-iaaM ^- mutant was shown to be due to an inhibitory effect of the T-ipt gene, since a TA-iaaM ^- /T-ipt ^- double mutant was fully virulent. We conclude that the TA-iaaM gene of large TA strains is specifically required to counteract the tumour growth inhibiting activity of the T-ipt gene. Both TA-iaaM and T-ipt are absent from the small TA strains. A model on the roles and interactions of the different oncogenes in large TA and small TA strains is presented.     

Variation of growth form parameters inCapsella (Cruciferae)

Growth form parameters ofCapsella bursa-pastoris populations, including a wide range of different environments, have been analyzed from random block field and growth chamber experiments. Changes in one character are often correlated with changes in another. Of special interest are correlations detected with the onset of first flowering. Variation in each of the characters is clearly influenced by both phenotypic and genotypic components. However, genotype — environment interactions are also subject to variation. Therefore, the adaptive significance of a given parameter is not found to be constant over the entire geographical range of the genus. Alpine populations tend to shift from annual to biannual life cycles.Part of a series Adaptation in life history traits of colonizing plant species. Part of a doctoral thesis by the first author. Dedicated to Prof. Dr.Karl Mägdefrau on the occasion of his 80th birthday.     

The spermatozoon of Oikopleura dioica Fol (Larvacea,Tunicata)

Summary The spermatozoon of Oikopleura dioica is about 30 m long, with a spherical head, about 1 m wide, a 3 m long and 1 m wide midpiece, and a 25 m long tail with a tapered end piece. The head contains a nucleus with the chromatin volume limited to about 0.1 m³. A small acrosome is found in an anterior inpocketing, and a flagellar basal body in a posterior inpocketing of the nucleus. The midpiece contains a single mitochondrion with the flagellar axoneme embedded in a groove along its medial surface. The flagellar axoneme has the typical 9 + 2 substructure, and the basal body the typical 9+0 substructure. A second centriole and special anchoring fibres are absent.     

Lectin histochemical localization of N- and O-linked oligosaccharides during the spermiogenesis of the urodele amphibian Pleurodeles waltl

The aim of this work is the characterization of the glycoconjugates of the spermatids during the spermiogenesis of the testis of an urodele amphibian, Pleurodeles waltl, by means of lectins in combination with several chemical and enzymatic procedures, in order to establish the distribution of N- and O-linked oligosaccharides in these cells. The acrosome was the most relevant lectin-labeled structure. The O-linked oligosaccharides contained DBA- and SBA-positive GalNAc, AAA-positive Fuc and PNA-positive Gal1,3GalNAc. Sialic acid was scarcely observed, the Neu5Ac2,-3Gal1,4GlcNAc sequence was found in N-linked oligosaccharides. Additionally, N-linked oligosaccharides containing HPA-positive GalNAc and AAA-positive Fuc were found. Moreover, with some lectins the acrosome showed a variable composition of the oligosaccharides in the different steps of the sperm maturation. Some residues were found only in the early steps in maturating acrosome, while others were in the later steps, showing that acrosomal glycoconjugates are modified during acrosome development in spermiogenesis. The changes observed during acrosome maturation suggest the existence of a predetermined pattern of storage of the acrosome components and a progressive compression of them.     

Demonstration of 2n spermatids in carriers of the “sex reversed” factor in the mouse by feulgen cytophotometry

Summary The Sex Reversed factor (Sxr) leads to development of XX males. The condition is transmitted by XY-Sxr males. The testes of XY-Sxr carriers are characterized by patches of defective spermatogenesis with meiotic failure and appearance of extraordinary large spermatids. In the present study DNA content of the large spermatids is determined by Feulgen DNA measurement using a scanning cytophotometer. The large spermatids in XY-Sxr testes are shown to be 2n.This study is dedicated to Prof. Dr. W. Graumann on occasion of his 65th birthday     

Fine structure of boar spermatozoa

Summary The fine structure of epididymal spermatozoa of boars was studied, with special regard to the head cytoplasm, the neck, and the axial filament. Epon embedding and staining with heavy metals was used.The acrosome consists of a moderately opaque, homogeneous substance bounded by a single membrane. Within the distinct equatorial segment, the acrosome is very thin and separated from the nuclear membrane by a narrow rim of moderately dense material, which may be related to the perforatorium of rat spermatozoa.The postnuclear cap consists of a dense, homogenous substance inside the cell membrane and is stainable with phosphotungstic acid.The fibre structures of the neck are surrounded by folded extensions of the nuclear membrane. Two short, dark rods appear in the centre of the neck. The light segments of the coarse, peripheral fibres are merely deep notches in the fibre substance. The coarse peripheral fibres reach their maximal thickness at the anterior end of the middle piece. They taper rapidly anteriorly from this point and more gradually posteriorly. Irregular bridges connect them with each other in the anterior middle piece.The central 9+2 fibrils of the axial filament have distinct arms and spokes in the middle piece and main piece. The subfibrils connected with the arms and spokes appear to be solid, except in the neck and end pieces. The two central fibrils run through the neck to the wall of the proximal centriole. Acknowledgements. We wish to express our sincere gratitude to Dr. B. Afzelius, the Wenner-Gren Institute, Stockholm, for helpful discussions regarding tail fine structure, and to Dr. J. Luft, Department of Anatomy, University of Washington, Seattle, Wash., U.S.A., for the generous supply of ingredients for the Epon embedding procedure.     

Protoplasmic streaming in the giant unicellular green algaAcetabularia mediterranea

Summary Protoplasmic Streaming inAcetabularia mediteranea has been studied by microcinematography in 1. germinating zygotes, 2. germlings before the differentiation of rhizoids and apices, 3. young cells with rhizoids and apices, 4. vegetative cells-several centimeters in length, 5. cells with a maximum sized cap, containing secondary nuclei, and 6. cells after cyst formation. Intracellular transport is found to occur at a network-system of thin filaments and at a different system of headed streaming bands. At the network of filaments chloroplasts are found to move at a velocity of 1–2 m/sec. Headed streaming bands move along the filaments and may lead without interruption from the rhizoid to the apex of the cell andvice versa. The front zone of the streaming bands is occupied by a leading cytoplasmic head-structure. Small vesicles, polyphosphate granula and secondary nuclei are the predominant moving structures in headed streaming bands. The velocity of these particles is found to be 3–11 m/sec. The filament system is found during all developmental stages. Headed streaming bands are undetectable in germinating zygotes and develop from small cytoplasmic droplets in germlings to broad heavily loaded bands in the huge vegetative cell.Transport of secondary nuclei by headed streaming bands is not observed during mitotic divisions and after cyst formation, though moving bands are still present for several weeks after cyst formation.     

Quantitative,three-dimensional ultrastructure of isolated corn (Zea mays) sperm cells

Summary Five isolatedZea mays sperm cells, taken from the same population as used for a previous morphometric study, were serially ultrathin sectioned and computer-reconstructed to yield three-dimensional images as well as quantitative data. All cells were found to be essentially spherical and to contain a full complement of cell constituents except plastids and microtubules. The nuclei of three cells were highly curved into a C or V shape while the other two nuclei were not curved, but were more spherical to disc shaped. The three curved nuclei were heterochromatic in appearance, the other two were more euchromatic. Mitochondria were closely associated with the nuclei, were predominately in the form of large, variously shaped complexes, and ranged in number from 7 to approximately 74 per cell. Dictyosomes tended not to be close to the nucleus and ranged in number from 6 to 23 per cell. The endoplasmic reticulum was similarly not typically associated with the nucleus, and varied from extensive sheet-like areas to small membranous whorls. In addition to confirming the findings of previous studies on isolated corn sperm cells and providing new three-dimensional and distribution data, the results of the present work underscore the existence of a high degree of morphological variability amongZea mays sperm cells of a population.Abbreviations ER endoplasmic reticulum - SD standard deviation     

Ultrastructural analysis ofSpinacia oleracea sperm cells isolated from mature pollen grains

Summary In isolated condition, the sperm cells ofSpinacia oleracea are no longer arranged in pairs as in the pollen grain. The vegetative membrane, which surrounds a sperm cell pair in a mature pollen grain, is lost during the isolation procedure. The sperm cells become spherical in shape.The isolated sperm cell is surrounded by an intact plasma membrane. The heterochromatic or euchromatic sperm cell nucleus is located in the cell center. Mitochondria are round to oval and have distinct cristae. Often they are clustered in groups of 5 to 10 mitochondria. Dictyosomes are present in the cytoplasm and consist of 4 to 5 cisterns. Endoplasmatic reticulum is mostly situated at the sperm cell periphery, as single cisterns very near the plasma membrane.From diameters of sectioned sperm cells in electron micrographs, it is possible to calculate the average diameter of the whole sperm cell. This average diameter is 3.66 m with a variation of 3.0 m to 4.2 m, resulting in an average volume of 25.6 m³. The nuclear volume is 12.8 m³ (50.0% of the whole cell) and the mitochondrial volume is 0.7 m³ (2.5% of the whole cell). The frequency distribution of the isolated sperm cells diameters shows only one peak with a normal distribution, indicating that there is no dimorphism in volume.     

Untersuchungen am Ovar von Bruchidius obtectus Say. (Coleoptera-Polyphaga) zur Klärung des Oocytenwachstums in der Prävitellogenese

Zusammenfassung Im ersten Teil der Arbeit werden die Ovariolen adulter Imagines von Bruchidius obtectus licht- und elektronenmikroskopisch untersucht. Durch den Nachweis von Nährsträngen, die die Oocyten mit den Nährzellen der Endkammer verbinden, konnte erstmals gezeigt werden, daß Bruchidius telotroph-meroistische Ovariolen besitzt. Die Nährzellen, deren Kerne kettenförmige Nukleolen aufweisen, bilden bei den Imagines ein Syncytium, das von einem räumlichen Maschennetz aus interstitiellen Zellen stabilisiert wird. In den Oocytenkernen entsteht während der Prävitellogenese eine Karyosphäre, von der aus Nukleolarkörper, Binnenkörper und segmentierte Längsstrukturen gebildet werden. Die Nukleolarkörper und die kettenförmigen Nährzellnukleolen werden als multiple Nukleolen diskutiert.Der zweite Teil der Arbeit stellt eine ontogenetische Untersuchung des Ovariolengewebes dar. Danach entsteht das Nährzellsyncytium in der Phase der Imaginalhäutung aus einem zellulär-fusomalen Verband. Die morphologische Abgrenzung der Ei- und Nährzellen voneinander sowie die Ausbildung von Nährsträngen finden ebenfalls in dieser Entwicklungsphase statt. Die präsumptiven Ei- und Nährzellen durchlaufen auf dem Puppenstadium das Pachytän der Prophase der Meiose. Damit weisen sich die Nährzellen als Keimbahnabkömmlinge aus.Im dritten Teil der Untersuchungen erfolgt eine Analyse der DNA- und RNA-Synthese sowie des RNA-Transports in dem Ovariolengewebe adulter Imagines. DNA Markierungen mit ³H-Thymidin lassen auf einen, wenn auch geringen, Polyploidiegrad der Nährzellkerne schließen. Markierungen mit ³H-Uridin belegen eine hohe RNA-Syntheserate der Nährzellkerne. Mit nahezu gleicher Intensität wie die Nährzellkerne synthetisieren auch die Oocytenkerne RNA, obwohl sie eine Karyosphäre bilden. Mit Hilfe von Markierungsgradienten im Ooplasma sowie von Nährstrangmarkierungen gelang der Nachweis eines RNA-Transportes von Nährzellsyncytium über die Nährstränge in die Oocyten.Abschließend wird das telotrophe Ovar von Bruchidius (Coleoptera-Polyphaga) dem telotrophen Ovar der Heteropteren gegenübergestellt. Der Vergleich legt eine konvergente Entwicklung dieses Ovartyps bei Insekten nahe.

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The growth of oocytes during previtellogenesis in the ovary of Bruchidius obtectus say. (Colepotera-Polyphaga)

Summary In the first part of the investigation the ovarioles of adult imagines are analyzed by light and electron microscopy. It is shown that nutritive cords connect the oocytes with the apical trophic tissue, demonstrating that Bruchidius has telotroph-meroistic ovarioles. The trophic tissue, in which the nurse cell nuclei contain chain-like nucleoli, is a syncytium stabilized by a three-dimensional network of interstitial cells. During previtellogenesis, a karyosphere is formed in oocyte nuclei in which nucleolar bodies, endobodies, and filament bodies originate. The nucleolar bodies and the chain-like nucleoli of nurse cells are considered to be multiple nucleoli.In the second part, the development of the ovariole tissue during ontogenesis is studied. The syncytial trophic tissue derives from a cellular-fusomal organization during the phase of molting. During the same period, the morphological distinction between nurse cells and oocytes as well as the development of nutritive cords take place. Nurse cells are derived from the germ-line, since, during pupal stages, both the prospective oocytes and the prospective nurse cells undergo the prophase of meiosis up to pachytene.The third part is an investigation of DNA- and RNA-synthesis and RNA-transport in the ovariole tissue of adult imagines. DNA labelling with tritiated thymidine shows a small degree of polyploidisation in nurse cell nuclei. By labelling with tritiated uridine, a high rate of RNA-synthesis could be demonstrated in nurse cell nuclei. A similar amount of RNA-synthesis exists in oocyte nuclei, even if they form a karyosphere. The transport of RNA from the apical trophic tissue via the nutritive cords into the oocytes is demonstrated by silver grain gradients over the ooplasm and by the labelling of nutritive cords.Finally, the telotrophic ovary of Bruchidius (Coleoptera-Polyphaga) is compared with the telotrophic ovary of Heteroptera, suggesting a convergent development of telotroph-meroistic ovaries in insects.

Meinem verstorbenen Lehrer Herrn Prof. Dr. Karlheinz Bier bin ich für die Überlassung des Themas und für die rege Anteilnahme am Fortgang der Arbeit zu großem Dank verpflichtet. Ebenso gilt mein Dank Herrn Prof. Dr. Klaus Heckmann, der mir die Fortsetzung der Arbeit ermöglichte. Für zahlreiche Diskussionsbeiträge und kritische Anmerkungen danke ich Herrn Prof. Dr. Oswald Hess, Herrn Dr. Udo Mays, Herrn Prof. Dr. Karl Müller und Herrn Dr. Fritz Weber. Frau Marianne Unger danke ich für die technische Hilfe bei der Anfertigung des Schemas.     

Dense-core vesicles in motor nerve terminals

Summary Motor nerve terminals on white and intermediate muscle fibers of the Atlantic hagfish (Myxine glutinosa, L.) contain translucent synpatic vesicles and about 1–2% dense-core vesicles. Terminals on red muscle fibers contain up to 40% dense-core vesicles with diameter 800–1100 Å. Examinations for formaldehyde-induced fluorescence indicate yellow fluorescence (5-HT ?) apparently corresponding with terminal axons on red muscle fibers in craniovelar muscles. Possibly red muscle fibers of Myxine receive monoaminergic innervation.The author is indebted to Dr. Finn Walvig, Biological station, University of Oslo, Drøbak, for supply of hagfishes.     

The arrangement of chromosomes in nuclei of sperm from plethodontid salamanders

Plethodontid salamanders have n = 13 or 14 large metacentric or sub-metacentric chromosomes. Sperm nuclei from Plethodon cinereus measure 72×1 m. The nucleoprotein of spermatids is at first finely granular. In elongate spermatids it clumps into larger granules, which then fuse to form the compact nucleoprotein of the mature sperm. The nuclei of mature sperm are negatively birefringent with respect to their length. — ³H RNA complementary to high-density satellite DNA of centromeric heterochromatin in P. cinereus has been hybridized in-situ to spermatids and sperm, and its site of binding to these cells has been examined by autoradiography. Labelling of round spermatid nuclei is localized in a single patch. Elongate spermatid nuclei are labelled only over the rear quarter of the nucleus. Label over the nuclei of mature sperm is localized in a region extending 10–20 m forwards from the rear of the nucleus. — In P. cinereus the ribosomal genes are located near the centromere on the short arm of chromosome 7. ³H ribosomal RNA hybridizes to a single patch in round spermatid nuclei. Elongate spermatid nuclei show label over a short segment of the rear half of the nucleus. In spermatids nearing maturity the labelled region is never more than 20 m long. — These results indicate that in P. cinereus each chromosome is arranged in a U formation with its centromere at the base of the sperm nucleus, and its arms extended forwards along the length of the nucleus. — Among plethodontids, increase in C value and corresponding increase in chromosome size is accompanied by increase in the length rather than the width of the sperm nucleus. — ³H ribosomal RNA hybridizes to a short segment in spermatid and sperm nuclei from Xenopus and Triturus. In these animals, the position of the labelled segment varies from sperm to sperm.     

Coastal dune stability: The effect of meteorological conditions and vegetation

Quantitative investigations and research conducted along the north coast of New South Wales, Australia are evaluated with respect to coastal processes, coastal alignment, meteorological data, dune dimensions, dune vegetative cover, development on the dunal area and dune management.The data available covered an assessment of the extent of dune instabilities, an assessment of long term coastline movements, a study of the effect of a cyclone and storm surge, and an assessment and evaluation of a phase of extreme coastline erosion. Specific situations are described and evaluated within the above context. The evaluations are used to determine the extent of coastal dune areas required to be designated as buffer zone in land use planning. The extent of the zone required is dependent upon expected magnitude of wave erosion. Magnitude of wave erosion was found to be proportional to the interaction of coastal processes during periods of extreme erosive factors and the beach dune characteristics for the particular section of coastline. It was found that man's influence on this natural interaction can be a dominating factor in determining beach dune characteristics and therefore the magnitude of wave erosion. — management of the beach dunal area to maintain an acceptable dynamic equilibrium of the beach dune line by a vegetated sand dune of specific dimensions is possible despite weather conditions, if a designated buffer zone is maintained.Presented at the Seventh International Biometeorological Congress, 17–23 August 1975, College Park, Maryland, USA.     

Die Homologie des Perigons der Zingiberaceen Ein Beitrag zur Morphologie und Phylogenie des Monokotylen-Perigons

Nicolaia elatior is used as an example to demonstrate that the mucronate tepals ofZingiberaceae correspond to hypsophylls (bracts) consisting of a leaf sheath and a rudimentary Oberblatt (= leaf petiole + lamina) represented by the mucro. Evidence for this interpretation is furnished by all available criteria: leaf sequence (exhibiting a complete continuum of forms from foliage leaves over cata- and hypsophylls to the tepals), nervature, and ontogeny.The present conception is compared with the well-founded thesis ofLeinfellner that the perigone ofLiliaceae is derived from the androecium. The different morphological status of the perigone in both families is not regarded as the result of different phylogenetic origin, but as a manifestation of morphogenetic transgressions from one phyllome category to an adjacent one: In theLiliaceae the perigone is under a strong morphogenetic influence of the androecium, and therefore displays staminal characters, in theZingiberaceae it is under the dominating influence of the extrafloral region, and thus appears as a hypsophyllous structure. If this assumption of a morphologically oscillating perigone is correct, it will be fundamentally impossible to demonstrate unequivocally the phylogenetic origin of the monocotyledonous perigone.

Im wissenschaftlichen Werk Prof. Dr.Walter Leinfellners steht an erster Stelle die Morphologie der Blütenorgane. Als sein dankbarer Schüler möchte ich ihm aus Anlaß seines 70. Geburtstages die folgende Studie zu einem Thema zueignen, das ihn wie mich gleichermaßen angesprochen hat und schon Gegenstand der Forschungsarbeit des Jubilars war: die Homologie des Monokotylen-Perigons.     

The carotenoids of Flavobacterium strain R1560

The main carotenoid of Flavobacterium strain R1560 has been identified as (3R,3R)-zeaxanthin. Also present were small amounts of 15-cis-phytoene, phytofluene, -carotene (7,8,7,8-tetrahydro-, -carotene plus 7,8,11,12-tetrahydro-, -carotene), neurosporene, lycopene, -zeacarotene, -carotene, -carotene, -cryptoxanthin, rubixanthin, 3-hydroxy--zeacarotene and several apo-carotenals. Zeaxanthin production was inhibited by nicotine (10 mM), and lycopene and rubixanthin accumulated. The biosynthesis of zeaxanthin is discussed in terms of pathways and also of half-molecule reaction sequences. The presence of zeaxanthin may be a characteristic of a group of Flavobacterium species, and may thus be useful in the taxonomic classification of these organisms.     

Nematodes from the Strait of Magellan and the Beagle Channel (Chile): the genera Cervonema and Laimella (Comesomatidae: Nematoda)

Five species of Cervonema and four species of Laimella are described from the Strait of Magellan and the Beagle Channel, Chile, six species of which are new to science. Cervonema chilensisn. sp. and Cervonema hermanin. sp. are separated from other known species of Cervonema by a short cervical region (less than one head diameter from the front end to the anterior border of the amphids). Cervonema chilensisn. sp. is characterised by a tail length of 5 anal diameters with posterior half filiform; Cervonema hermani n. sp. is characterised by a tail length of 6–9 anal diameter and posterior part (75%) cylindrical. Cervonema shiaen. sp. is characterised by the cephalic seta 4 m long, amphids 9–10 m in diameter; spicules 16 m long and 0.8–0.9 abd; tail 4.7–5.4 anal diameter and 50% posterior part filiform; 4–5 minute precloacal supplements. Laimella subterminatan. sp. is characterised by the subterminal position of the buccal cavity which separates it from the other species of the genus. Laimella annaen. sp. is characterised by the head diameter 9–11 m, cephalic setae and external labial setae 9 + 5 m long, respectively, amphids 7 m in diameter; spicules 28–30 m long; tail 14–17 anal diameter and posterior part (75%) filiform; 5 precloacal supplements. Laimella sandraen. sp. is very close to Laimella annaen.sp. in having similar cephalic sensilla, amphids and spicules. Laimella sandraen. sp., however, can be separated from L.annaen. sp. by the shape of head and the structure of sperm cells, the total body length and the cylindrical part of tail. Cervonema papillatum Jensen, 1988, C. tenuicauda (Stekhoven, 1950) and L. longicauda Cobb, 1920 are found in this area as well. The key of all known species of Cervonemaand Laimellais presented.     

Spermatogenesis revisited

Summary This ultrastructural study confirms and extends the light microscope findings of Bryan (1971) concerning the presence and developmental fate of multinucleate spermatids. Four main classes of cells: uninucleate-individual, uninucleate-conjoined, multinucleate-conjoined, and multinucleate-individual, were identified along with a few instances of more complex syncytial organizations. When the respective nuclei in a given multinucleate are far enough apart, each develops autonomously but in synchrony with its neighbors. When nuclei are intimately associated, the normal pattern of spermiogenesis may be altered, giving rise to highly bizarre spermatozoa. Commonly, a single Golgi complex serves a pair of nuclei and gives rise to a T-shaped acrosome which binds the nuclei together. During the ensuing nuclear elongation phase, such units are invested by a single manchette. Pairs of axonemes within a common plasma membrane have also been encountered. These ultrastructural findings indicate that multinucleate spermatids are true components (not artifacts) of the seminiferous epithelium of normal animals. The presence of such cells and the unusual developmental consequences which can arise as a result of the multinucleate state must be taken into account when evaluating the course of spermatogenesis in cases of mutation- or chemically-induced infertility.These studies have been supported by funds from The Office of General Research, The University of Georgia.     

Differential response to irradiation in offspring of freshwater and seawater substrains of Poecilia (Lebistes) reticulata peters in the “guppy male courtship activity test”

Summary An inbred strain (Istanbul) of guppies was divided into two substrains, one of which was maintained and bred in seawater. The offspring of irradiated animals of both substrains (1000 R X-rays to spermatogonia and oogonia of neonatal fish) were tested in a new gruppy male courtship activity test and compared with control groups. The postirradiation response in the seawater substrain was more intense than in the freshwater substrain.Dedicated to Prof.Dr.Dr.h.c.mult. Curt Kosswig on the occasion of his 75th birthday