Electron microscope observations of some peripheral synapses in the sensory pathway of the sucker of Octopus vulgaris

Summary A synaptic axo-dendritic linkage is described between primary receptors lying in the epithelia of the sucker of Octopus and encapsulated nerve cells found near the rim of the sucker in the subepithelial connective tissue. These synapses are postulated to perform a drastic reduction of inputs between the primary receptors of the order of more than ten thousand and the subjacent encapsulated nerve cells of the order of some hundreds. The morphology of these cells as well as that of the synaptic structures are described from electron microscope studies. Aknowledgement. This work was done at University College London, while I was in receipt of a Medical Research Council grant.I am deeply indebted to Prof. J. Z. Young F. R. S. for support and criticism, and to Dr. E. G. Gray for advice and discussion. My thanks are due to Mr. A. Aldrich for the photographs.     

Ultrastructure of the tube foot wall of a regular echinoid,Diadema antillarum Philippi

Summary An ultrastructural study of the tube foot wall of a regular echinoid,Diadema antillarum, was made. Ciliated microvillous epithelial cells, their inclusions, amoebocytes, and the arrangement of collagen and muscle in the tube feet are described. The neuropile, together with its vesicular components and possible neurosecretory elements, is considered and discussed as are connective tissue bridges across the lumen. Consideration is given to possible functions for the various components of the tube foot.I am indebted to ProfessorN. Millott for his help and encouragement during the course of this work, to Mr.Raynor L. Jones for his expert technical assistance, and to Dr.H. G. Vevers and the Zoological Society of London.     

The ultrastructure of monkey eccrine sweat glands

Summary The ultrastructure of monkey eccrine sweat glands is described. The secretory portion of the sweat gland is discussed in detail. The morphological differences in the secretory coil using three different fixatives and fixative combinations are emphasized. The secretory product of dark cells is seen to have three distinct appearances depending upon the fixative used. The biochemical significance of the latter finding is discussed. The appearance of clear cell cytoplasmic processes is described using the different fixatives. The similarity of adjacent clear cell processes to those of avian salt glands is pointed out and discussed. Evidence is presented to indicate that dark cells arise from clear cells via an intermediate cell type. The appearance of the clear cell plasma membrane is described and the necessity for the use of the general term multilaminar plasma membrane is discussed.Supported by U.S.P.H.S. grant 5 T 1-GM-29 F-04 AS. The author would like to express his gratitude to the Lederle Laboratories and in particular to Dr.James Vickers for providing the tissue. Sincere thanks is given to Mrs.Dagmar Graham and Mrs.Ditza Springer for technical assistance and also to MissMary Lorenc for preparation of the diagram. In addition, I would like to thank Dr.J. A. G. Rhodin for his criticism and advice.     

Fine structure of the Paraventricular organ of Xenopus laevis tadpoles

Summary The ultrastructure of the Paraventricular organ in the hypothalamus of Xenopus laevis tadpoles is described. It appeares that the Paraventricular organ of this anuran species is homologous with the Organon vasculosum hypothalami or the Paraventricular organ of other vertebrates.The Paraventricular organ of Xenopus laevis is characterized by an ependymal lining with only few cilia and by two types of nerve cells. Both types of nerve cells have ventricular processes, protruding into the lumen of the third ventricle and forming a network. The protrusions bear cilia of the 8+1 pattern. It has been possible to distinguish both types of nerve cells on account of their dense-core vesicles. A secretory function of both cell types is suggested.In a region close to the Paraventricular organ, another granulated type of nerve cell has been observed. A relationship between these cells and the preoptic nucleus is discussed.The author thanks Prof. Dr. P. G. W. J. van Oordt for his helpful comments and criticism, Mr. H. van Kooten for photographic assistance and Mr. F. Dijk for technical assistance.     

Structure of the parapineal organ of the adult rainbow trout,Salmo gairdneri Richardson

Summary The parapineal organ of the teleost Salmo gairdneri Richardsonsu1 was investigated with the light and electron microscopes. It is a small cell mass, 0.1–0.3 mm in diameter, containing a narrow lumen and consistently situated to the left of the pineal stalk and dorsal to the left habenular nucleus. It is connected with the habenular nucleus through a conspicuous parapineal tract. The parapineal organ continues to grow at least until the fish reaches sexual maturity and shows no sign of cellular degeneration at the age of two years.The parapineal tissue consists of supporting cells and nerve cells; the latter give rise to the axons of the parapineal tract. Furthermore, a small number of receptor cells of the type existing in the pineal organ is present. No morphological evidence was obtained to suggest a sensory or secretory function of the parapineal organ.The existence of the parapineal organ in the adult pike, Esox lucius, L., and of a connection between the pineal tract and the habenular commissure in Salmo gairdneri is briefly reported. The results are discussed in the light of existing literature.Work done with the aid of a research scholarship from the Alexander von Humboldt Foundation, Bad Godesberg, Germany. —The electron microscope used in this study was placed at the disposal of Prof. Oksche by the Deutsche Forschungsgemeinschaft. —I wish to thank Prof. Oksche for the facilities made available at his institute and for his helpful interest in my work.     

Contributions to the morphology,anatomy, and karyology ofRhabdodendron,and a reconsideration of the systematic position of theRhabdodendronaceae

Rhabdodendron macrophyllum (Spruce ex Benth.)Huber andR. amazonicum (Spruce exBenth.)Huber differ in several anatomical and morphological characters (secretory cavities, hypoderm, peltate hairs, internodal region and petiole). A position of the monotypicRhabdodendronaceae in theCentrospermae as recently suggested is hardly supported: Peltate hairs, lysigenous secretory cavities and spicular cells in the leaves, multilacunar nodes, chromosome number (R. macrophyllum: n = 10; first count for the genus resp. family), ± simultaneous (or slightly centripetal) development of the androeceum, anacrostyly and two ovules in the unicarpellate gynoeceum, apparent disc, monotelic racemes, and data available from literature (pollen, sieve tube plastids) clearly indicate a close affinity toRutaceae, and even make the family rank ofRhabdodendron questionable.     

The genusIschnea (Asteraceae,Senecioneae) in New Guinea

The endemic New Guinean genusIschnea F. Muell. (Asteraceae, Senecioneae, Blennospermatinae) is revised and four species are recognized. Characters of special interest are tubeless ray florets, male disc florets, and secretory spaces in leaves. A principal component analysis is made on theIschnea elachoglossa F. Muell. complex which shows great variation. One new species,I. capellana Swenson, from the Star Mountains, is described. A key, illustrations, and distribution maps to all species are supplied.     

The metabolism of p-hydroxybenzoate by Rhodopseudomonas palustris and its regulation

Summary Rhodopseudomonas palustris metabolizes p-hydroxybenzoate aerobically via a series of specific reactions which are partly described. The pathway similar to that described for aerobic pseudomonads. The requisite enzymes are absent in extracts of cells grown anaerobically under photosynthetic conditions with p-hydroxybenzoate, benzoate and malate, or aerobically with benzoate or malate. An intermediate of the reaction sequence presumably induces in a retrograde fashion.Dedicated to Prof. C. B. van Niel on the occasion of his 70th birthday. I wish especially to acknowledge a debt to Prof. C. B. van Niel, who offered an assistant so much encouragement and suggested this and so many other problems in his summer Microbiology Course.The early portion of this work was done in collaboration with Dr. E. R. Leadbetter in the laboratory of R. Y. Stanier at Berkeley. Mrs. C. Feist generously provided a sample of -hydroxymuconic semialdehyde. This investigation was supported by the U.S. Public Health Service, Grant HD-02448.     

The fine structure of sensory receptor processes in the auricular epithelium of the planarian,Dugesia tigrina

Summary The marginal epithelium of the lateral auricles of the planarian, Dugesia tigrina, includes a cell type with surface cilia and microvilli, a basal nucleus, and dense cytoplasm containing secretory vacuoles, Golgi elements, mitochondria and ribosomes. Through channels within the epithelial cytoplasm, cellular processes, interpreted as extensions of neurosensory receptor cells located in the subepidermis, project to the surface. The receptor processes, containing microtubules, mitochondria, vesicles and an agranular tubular reticulum, project beyond the epithelial cell surface; one or two cilia each emerge from a basal body in the apex of the projection. Close to the point of emergence to the epithelial surface, each cylindrical receptor process is surrounded by a collar-like septate junction between adjacent plasma membranes. The cilia of the projections differ from those of the epithelial cells in diameter, density of matrix and in the banding patterns of the rootlets. A few projections appear with the apex and basal body retracted below the epithelial surface. The possible function of these ciliated processes in sensory reception is discussed.This work was supported by Grant No. SO 1 FR 5369 from the U.S. Public Health Service to the University of Illinois at the Medical Center.I thank Dr. J. P. Marbarger, Director of the Research Resources Laboratory, for use of the electron microscope facilities, Miss Irena Kairys for technical help, Miss Marie Jaeger for assistance with photography, and Mr. Robert Parshall for the drawing.To Professor Arthur Wagg Pollister, I respectfully dedicate this article on the occasion of his retirement from Columbia University.     

Ultimobranchial gland ultrastructure of larval axolotls,Ambystoma mexicanum shaw,with some observations on the newt,Pleurodeles waltlii Micahelles

Summary The fine structure of the ultimobranchial (UB) glands of two common laboratory urodeles, viz., larval axolotls, Ambystoma mexicanum Shaw and adult Pleurodeles waltlii Micahelles, is described and compared in what is believed to be the first ultrastructural report on urodele UB glands. The axolotl UB gland shows a wide variety of form, being represented by an elongated diffuse series of follicles and sometimes by one or two large discrete terminal follicular bodies. In these axolotl UB glands up to four cell categories are distinguishable including a tonofilamentous cell and a secretory cell that is possibly homologous with calcitonin-producing C cells of anurans or other vertebrates. These two cell categories are also found in the Pleurodeles gland. The possible significance of the various cells is considered.We are indebted to the Central Research Fund of London University and the Science Research Council for awards making this research possible. We would also like to thank Dr. Eyal of the Dept. of Zoology, The Hebrew University, Jerusalem for the gift of the Pleurodeles and Mr. Raynor L. Jones for his excellent technical assistance.     

Microtubules in some unicellular glands of two leeches

Summary What appear to be two types of unicellular glands are found in the integument of the leech, Helobdella stagnalis. Type I cells are characterized by a peripheral, subplasmalemmal sack of rough endoplasmic reticulum and accumulations of secretory product in the form of small membrane bound droplets. Type II cells are characterized by large numbers of closely opposed sacks of rough endoplasmic reticulum and secretory product in the form of large, evidently amorphous accumulations of secretory product.Both cell types attenuate into long, slender processes through which the secretory product passes to the surface of the leech. Each process is characterized by a subplasmalemmal sack of ER which runs the entire length of the process and is continuous, at the proximal end of the process, with sacks of rough ER. Associated with the inner member of the ER membrane pair are microtubules with a diameter of approximately 240 Å.A similar arrangement of a subplasmalemmal ER sack associated with microtubules also is found in secretory processes of the leech, Macrobdella decora.The possible source and functions of these microtubules are discussed.This investigation was supported by Public Health Service grant number GM 723-04 of the National Institutes of Health.The author is greatly indebted to Dr. David B. Slautterback for his advice and encouragement during the course of this investigation.     

Ultrastructural observations on the parathyroid glands of Xenopus laevis Daudin

Summary The fine structure of the parathyroid glands of the anuran, Xenopus laevis Daudin is described during the metamorphosis of larvae and in young adults. Two distinct forms of epithelial cells are found viz.: dark and light cells and the significance of these cell conditions is considered and discussed. Parathyroid glands from young untreated toads are compared and contrasted with glands from toads maintained for prolonged periods in high concentrations, up to 1%, of calcium chloride in aqueous solution. The development of unusual membranous inclusions in the cytoplasm of the experimentally-treated toads is described.I am grateful to Messrs. R. L. Jones and Z. Podhorodecki for their expert technical assistance. I would also like to thank Professor N. Millott for his help and encouragement during the course of this work.     

Differential distribution of lectin-binding glycoconjugates in the secretory granules of hamster oviductal ampulla during the estrous cycle: a quantitative cytochemical analysis

 High resolution lectin-gold cytochemistry was used to quantitatively analyze the distribution of glycoconjugates in the hamster oviductal ampulla during the five stages of the estrous cycle. Lectins binding to N-acetyl-d-galactosamine-, d-galactose-, and sialic acid-associated glycoconjugates in the secretory granules of ampullary epithelial secretory cells showed staining of equal intensity throughout the five different stages of the estrous cycle. In contrast, the labeling intensity of glycoconjugates which contain N-acetylglucosamine as terminal sugar residues reached its maximum around the time of ovulation, i.e., at proestrus. Glycoconjugates which carry fucose and mannose as terminal sugar residues appeared to be totally absent from the secretory granules of the oviductal ampulla during the estrous cycle. Together, electron microscopic observations combined with quantitative results indicate that N-acetyl-d-galactosamine-, d-galactose-, and sialic acid-associated glycoconjugates may be secreted into the ampullary lumen irrespective of the stage of the estrous cycle, whereas the secretion of certain N-acetylglucosamine-associated glycoconjugates is stage specific and reaches its peak at the time of ovulation. These findings suggest that, at the time of ovulation, the ampullary epithelium changes its secretory activity and contributes its secretory products to the zona pellucida of oocytes freshly released from the ovary. Accepted: 10 August 1998     

New and noteworthyHabenaria spp. (Orchidaceae) from New Guinea and adjacent islands

5 new taxa ofHabenaria, namelyH. bougainvillae, H. elongata R. Br. var.leptophylla, H. ensigera, H. rechingeri andH. trichoglossa, are described and illustrated, with reference to affinities to related Australian and Indo-malayan species. The occurrence in New Guinea of severalHabenaria spp. typical for a savanna-like vegetation, led to look more thoroughly at these taxa:H. elongata R. Br. andH. ochroleuca R. Br., considered so far to be endemic in Northern Australia, andH. khasiana Hook. f., hitherto only known from southeastern Asia.Studies in the subtribeHabenariinae Bentham (Orchidaceae), 2.—Part 1: Candollea34, 357 (1979).Dedicated to Hofrat Prof. DrKarl Heinz Rechinger on the occasion of his 80th birthday. — On April 30, in the year 1927, the author and his brotherOtto Renz metKarl Heinz Rechinger on a small steam-boat in a stormy Aegaen Sea, travelling from Piraeus to the Northern Sporades Islands:Karl Heinz with destination to Chelidromia, the author andO. Renz to Skopelos. By this lucky chance a lasting friendship began.     

Ultrastructural features of the tegumental surface of a new metacercaria, Nematostrigea sp. (Trematoda: Strigeidae), with a search for potential taxonomically informative characters

The tegumental surface of a new strigeid metacercaria, Nematostrigea sp., which is a parasite of the freshwater fish Channa gachua (Hamilton) in central Vietnam, is described for the first time using scanning (SEM) and transmission (TEM) electron microscopy. In addition to the general tegumental surface in various parts of the body, details of the surface of the suckers, lappets and holdfast organ are presented, as are variations in the form and distribution of the body spines. As good taxonomic criteria are few in diplostomoid metacercariae at both specific and generic levels, a number of the ultrastructural features revealed may prove to represent taxonomically informative characters. These include the presence of: two rings of dome-shaped papillae localised at different levels on the rim of the oral sucker, a single ring of ciliated papillae on the inner margin of the ventral sucker and a band of dome-shaped papillae along the lateral margins of the broad body-fold in the ventral forebody; an unarmed oral sucker and anteroventral surface of the forebody, although the latter bears protuberant secretory pores; an armed ventral sucker covered by six-pointed spines, except on its rim; multi-pointed spines along the dorsal and ventral sides of the forebody, with the number of their teeth increasing posteriorly; multi-pointed spines on the forebody which gradually transform into single-pointed, more widely distributed spines on the hindbody, disappearing completely at posterior end of the body; the surface of the lappets with a particular distribution of pores leading to three types of secretory glands and three topographical modifications (areas where the surface is smooth, bears digitiform processes or bears recurved, dagger-shaped spines); and the surface of the holdfast organ which is covered with densely packed, straight or slightly curved, simple spines on its lateral surface but is smooth medially.     

The fine structure of blattarian prothoracic glands

Summary The ultrastructural characterization of the prothoracic glands derives interest from the fact that they are the only known source of a steroid hormone (ecdysone) among invertebrates. The present material includes nymphal glands of two blattarian species studied at graded intervals over a period of several intermolt cycles.Among the prominent cytological features of this organ are long and intricately interwoven cellular processes that may be separated from each other by extracellular channels with an average width of 0.5 . The plasma membranes of the cells facing these spaces are coated by an external lamina (boundary membrane) representing extensions of the same extracellular material that provides the connective tissue sheath of this and other insect organs. Micropinocytotic caveolae and vesicles present along this large cellular surface area may facilitate the transport of material between glandular cells and hemolymph, or vice versa.The cytoplasm contains a fairly moderate amount of membranous structures. Golgi units are distinctive but never spectacular; ergastoplasmic elements are sparse in most cells. This sparsity as well as the absence of membrane-bounded secretory granules is in line with the known steroidal nature of the secretory product involved. Some cells show a striking array of microtubules.Certain structural attributes of nucleoli, mitochondria, and lysosome-like bodies seem to vary in conjunction with distinct phases of the intermolt cycle.Dedicated to an inspiring teacher and loyal friend, Professor F. Wassermann on the occasion of his 80th birthday, August 13, 1964. — Supported by Research Grants AM-03984 and NB-02145 from the U.S.P.H.S. — I wish to thank Mrs. Cynthia Jones and Mr. Stanley Brown for their skillful assistance.     

A comparative ultrastructural study on ultimobranchial glands of some Israeli anurans (Bufo viridis,Rana ridibunda and Hyla arborea)

Summary The comparative fine structure of ultimobranchial (UB) glands of adult Israeli anurans (Bufo viridis, Rana ridibunda, Hyla arborea) taken in the wild during the breeding season is presented. Common aspects of the UB secretory cells are considered with especial reference to secretory granules, lipid droplets and tonofilaments. In B. viridis a second cell type with large electron-dense cytoplasmic granules is found in UB follicles. R. ridibunda and H. arborea UB follicles have a second cell type similar to goblet cells in appearance and these appear to be discharging their mucoid contents into the lumina of the follicles. The possible significance of these various cell types is considered.I am indebted to the Central Research Fund of London University for an award for apparatus and travel enabling a short research visit to the Dept. of Zoology, The Hebrew University, Jerusalem and am particularly indebted to Dr. Dvorah Boschwitz and her colleagues for their enormous help during my visit. I would also like to thank Alan D. Phillips for his assistance in the analysis of the material made possible by an award from the Science Research Council. My thanks are also due to Raynor L. Jones for his excellent technical assistance.     

The pancreatic islet system of the mouse (Mus musculus)

Summary The pancreatic islet in the mouse has a highly complex and heterogeneous structure. It contains Aa, Ab, Ac, B, C, D, E, and F cells. The classification of cell types is primarily based on the shape, size and electron opacity of secretory granules and on the spatial relationship of the granules to their unit membranes. Morphological evidence is supported by a statistical analysis of the size distribution of granules and of their membranes. Experimental immunization of mice with insulin, provides additional data to support the existence of eight different cell types in the islet of the normal animal and reveales marked immunological stimulation of B cells, secondary stimulation of Aa, D and F cells, atrophy of Ac cells and hyperplasia of C cells. It is proposed that corresponding cell types exist in other mammals and man. The experimental insulin immunization process appears to perform an immunofunctional analysis of the islet, and suggests that in mice the Aa, D and F cells might be involved in cell energy supply. Lipocaic and some pancreatic factors with insulin-like activity (NSILA) will likely find their morphological equivalents. It is proposed that chemical solubility techniques represent the most promising avenues of approach to the isolation of secretory products from the endocrine pancreas, and that the assay of these extracts should primarily be conducted at the cell level.Dedicated to Prof. Dr. med. W. Masshoff on his 60th birthday.The author is indebted to Dr. med. H. J. Stolpmann for guidance in applying the techniques of electron microscopy and wishes to express his special appreciation to Mrs. Marjanne Hinz for her valuable assistance in completing different aspects of this work and for her competent technical aid.     

On the glycocalyx,the external coat of the plasma membrane,of some secretory cells

Summary The free surface of epithelial cells of secretory organs (human placenta, lactating mammary gland of the rat, choroid plexus of man and rat) and of the accessory organs of the genital tract of the male rat is characterized by a plasmalemmal differentiation named glycocalyx or surface mucous coat. This structure is built up by filamentous or globular substructures.Two main ultrastructural types of the glyeocalyx were observed: 1) The filamentous type such as in the rat epididymis, which resembles the cat intestinal glyeocalyx (Ito, 1965) and that one of human transitional epithelium (Monis and Zambrano, 1968), and 2) The globular type, as observed in the lumen of the lactating mammary gland of the rat.Sialic acid was demonstrated histochemically in the luminal glyeocalyx of all organs studied. In addition, the glyeocalyx of acinar cells of the lactating mammary gland contains sulfate and phosphate groups which were identified by histochemical technics, using enzymatic digestion procedures, suggesting the chemical heterogeneity of this glyeocalyx.Present investigations follow the working hypothesis that the complex carbohydrates of glycocalyces become part of the product of activity of secreting cells.We thank Mr. Luis Iwakawa, Miss Silvia Falcón, Miss Elsa M. Orgnero for technical help, Miss Graciela Aliaga for secretarial assistance. Photography by Mr. H. Magnani. Dr. Hugo F. Carrer cooperated in the initial stages of this investigation.The authors acknowledge the use of the electron microscope of the Department of Pathology, Córdoba University Medical School, for which they thank Prof. E. Mosquera and Dr. E. Hliba. Dr. Hliba photographed picture number 4.     

The evidence for a meiotic process in the euglenineae

Summary Cells of Hyalophacus ocellatus are described which contain either a nuclear figure consisting of a double complement of highly condensed chromosomes arranged in pairs in the anterior half of the cell, or a huge posteriorly-placed nucleus consisting of long granular chromosomes which also show signs of pairing. These nuclear figures are quite unlike interphase nuclei or stages in mitosis and are thought to be stages in euglenoid meiosis.No evidence has been obtained for a sexual fusion of gametes or cells. Previous accounts of sexuality and autogamy in the Euglenineae are historically reviewed and critically discussed relative to the present observations.This paper is dedicated to Professor Dr. E. G. Pringsheim on the occasion of his 80th birthday, with gratitude both for his untiring advice on my research and for his friendship.