Pre-fertilization ovule development inCapsella: ultrastructure and ultracytochemical localization of acid phosphatase in the meiocyte

Summary Pre-meiotic and prophase I ovules ofCapsella bursa-pastoris (L.) Medic.(monosporic,Polygonum type of gametophyte development) were fixed routinely or incubated in a modified Gomori medium containing -glycerophosphate as a substrate. Prior to the beginning of meiosis the potential meiocyte is ultrastructurally similar to the other cells of the nucellus and is distinguished only by its size and position. At the initiation of prophase I dramatic ultrastructural and ultracytochemical changes take place in the female meiocyte. These include the sudden appearance of cytoplasmic structures composed of single and multiple concentric cisternae, distinctive changes in plastids and mitochondria, and the blebbing of 0.3 m double-membraned vesicles from the nuclear envelope. The concentric cisternae encapsulate portions of cytoplasm containing ribosomes, plastids, mitochondria, ER fragments and vesicles. Both single and multiple concentric cisternae localize high levels of acid phosphatase and function as autophagic vesicles (AVs) that sequester ribosomes and organelles for destruction during meiosis. Plastids stop dividing and become more spherical during prophase I. Some plastids localize acid phosphatase and many show continuities between the outer membrane and the plastid envelope and acid phosphatase-rich RER cisternae. Mitochondria appear as dense, contracted spheres or rods. Some mitochondria localize acid phosphatase but they do not show membrane confluencies with the ER. Some of the plastids and mitochondria that are segregated into the functional megaspore at meiosis II are destroyed but others apparantly survive meiosis and give rise to the plastid and mitochondrial populations of the young gametophyte (Schulz andJensen, unpublished). The lateral and end walls of the meiocyte show patches of intense aniline blue fluorescence and the chalazal end wall of the cell is perforated with large numbers of plasmodesmata.Research supported by NSF Grant PCM-79-11018. The authors gratefully acknowledge the valuable assistance of David Lee Ivans in this project.     

Ultrastructural immunocytochemistry and lectin histochemistry of the subcommissural organ in the snake Natrix maura with particular emphasis on its vascular and leptomeningeal projections

Summary The ependymal cells of the subcommissural organ (SCO) of the snake Natrix maura display long basal processes which terminate either on blood vessels or on the leptomeninges. The cell body and the basal processes contain a secretory material detectable immunocytochemically at the light-microscopic level using an antibody raised against bovine Reissner's fiber. The present investigation deals with the ultrastructural location in these cells of the (i) immunoreactive material; (ii) concanavalin A (Con A)-and wheat-germ agglutinin (WGA)-binding sites. In the subnuclear region the immunoreactive material was located within dilated cisternae of the rough endoplasmic reticulum and had affinity for Con A but not for WGA. In the supranuclear region the secretory material was exclusively located within numerous granules. Since all these granules showed affinity for WGA, they can be regarded as post-Golgi elements. Thus, at variance with the situation in the mammalian SCO, in the ophidian SCO most of the secretion is stored in secretory granules rather than in dilated cisternae of the rough endoplasmic reticulum. In the perivascular and leptomeningeal endings the immunoreactive material was located within granules which, because of their affinity for WGA, should also be regarded as true secretory granules derived from the Golgi apparatus. It is concluded that these granules are transported along the basal processes and accumulated in the perivascular and leptomeningeal endfeet. This observation favours the view of a local release of the content of these granules, since there is no evidence for a reverse transport of these granules all the way back from the distal termination to the apical pole, to be finally released into the ventricle.     

Studies on the ultrastructure of the human oviduct epithelium in different functional states

Summary The ultrastructure of the ampullar epithelium of the human oviduct was studied in 9 women in different phases of the sexual cycle and in pregnancy.Both kinds of cells (secretory and ciliated) showed morphological signs of micropinocytotic activity during the follicular phase, but no such activity during the luteal phase. Thus cyclic variations were observed in both ciliated and secretory cells. The secretory cells were provided with an extraneous coat, which was most conspicuous during the follicular phase. The Golgi apparatus was large. The mitochondria had transversal cristae. The endoplasmic reticulum consisted of cisternae with partly granular membranes. The ribosomes were partly membranebound and partly free. The appearance of the endoplasmic reticulum and the distribution and frequency of the ribosomes varied with the functional states. The ciliated cells were not provided with an extraneous coat. The Golgi apparatus was small. The mitochondria were numerous and had transversal cristae. Multivesicular bodies and dense bodies occurred in the nuclear region. Cilia as well as centrioles were provided with striated rootlets.This investigation was supported by a grant from the foundation Therèse och Johan Andersson Minne.The skil ful technical assistance of Miss Gunilla Runefeldt is gratefully acknowledged.     

The endomembrane system of differentiating carposporangia in the red algaChondria tenuissima: Occurrence and participation in secretion of polysaccharidic and proteinaceous substances

Summary The endomembrane system during carposporogenesis inChondria tenuissima was studied using electron microscopy and histochemistry. Profiles of the nucleus are convoluted, resulting in a highly increased surface area. Stacked cisternae are found within the peripheral part of the nucleus. Vesicles, tubules and membrane bound fibrillar bodies occur within the nucleoplasm. The endoplasmic reticulum surrounds the nuclear envelope.The endoplasmic reticulum and the Golgi apparatus, together with small transition vesicles, represent a functional unit. They form two different secretory substances during carposporogenesis. In young stages, carbohydrates are produced by normal dictyosomes within large, normal exocytotic Golgi vesicles. They do not react positively with PAS or Thiéry method and are believed to represent cell wall material. In later stages, the central area of the Golgi cisternae becomes filled with electron dense material. The individual cisternae are transformed into cored vesicles at the trans-face of the dictyosomes. The dense core of the vesicles is proteinaceous and stains with coomassie brilliant blue R. The peripheral fibrillar material is polysaccharidic and reacts positively using the Thiéry method. The contents of the cored vesicles are believed to participate in carpospore attachment. The ER gives rise to cytolysosomes in which starch grains are sequestrated and digested. Mucilaginous sacs seem to be similarly formed.     

Electron microscopic-immunocytochemical localization of adrenocorticotropin and melanocyte stimulating hormone in the pars intermedia cells of rats and mice

Summary Electron microscopic localization of adrenocorticotropin (ACTH) and melanocyte stimulating hormone (MSH) in light, dark and ACTH cells in the pars intermedia (PI) of rats and mice is attempted by using antisera to _p 1–24, _p 17–39 ACTH and _b MSH with the immunoglobulin-peroxidase bridge technique. All of the PI parenchymatous cells (light, dark and ACTH cells), except the marginal cuboidal and the ependymal like cells, in rats and mice show very good localization of ACTH and MSH staining. In the light and dark cells, stain of varying intensity is seen on the secretory granules, vesicles and also in many places on the surface of the rough endoplasmic reticulum. There is no staining on the mitochondria, in the nuclei or in the granules inside and around the cisternae of the Golgi complex. Dark stained dense core granules become larger and larger as they appear farther and farther away from the Golgi complex. On the other hand, in the ACTH cells of the PI, ACTH antisera show stronger stained granules in the Golgi complex including the cisternae, similar to the pars distalis (PD) ACTH cells. From these observations it is concluded that the corticotropin in light and dark cells, is not packaged or condensed in the Golgi complex like that in the ACTH cells. MSH synthesis in light and dark cells also seems to be similar to that of ACTH synthesis. It is likely that the granules accumulate ACTH and MSH secretions after they are liberated from the Golgi cisternae, and thus become bigger and bigger in size. In case of ACTH cells of PI and PD, corticotropin may be packaged in Golgi cisternae and the size of the granule does not change much. This shows that there are distinct immunocytochemical differences between the light, dark and ACTH cells of the PI. At the moment, it is difficult to say whether ACTH and MSH are present in the same granule or not.The present and previous studies show that the ACTH and MSH secretion in the PI of rats and mice depends on the hypothalamic neural control.This study was supported by MRC of Canada Grant nos. MA-3759, and MA-5160.The author gratefully wishes to thank Drs. P. Desaulles and W. Rittel (CIBA, Basle, Switzerland) for the synthetic _p 1–24 ACTH and _b MSH, Dr. R. F. Phifer for _p 17–39 ACTH, and Dr. S. S. Spicer for providing samples of rabbit anti-porcine 17–39 ACTH and anti-human ACTH sera, Drs. George Sétáló and Paul Nakane for their valuable advice. He also acknowledge the help of Mr. Shankar Nayak to prepare the antisera and the skilful technical assistance of Miss. Elise Poiré. He wishes to acknowledge Mr. Gatson Lambert for his photography.     

Ultrastructural, histochemical and cytochemical characterization of intestinal epithelial cells in Aplysia depilans (Gastropoda, Opisthobranchia)

To improve the current knowledge about the digestive system in opisthobranchs, light and electron microscopy methods were used to characterize the epithelial cells in the mid‐intestine of Aplysia depilans. This epithelium is mainly formed by columnar cells intermingled with two types of secretory cells, named mucous cells and granular cells. Columnar cells bear microvilli on their apical surface and most of them are ciliated. Mitochondria, multivesicular bodies, lysosomes and lipid droplets are the main components of the cytoplasm in the region above the nucleus of these cells. Peroxisomes are mainly found in middle and basal regions, usually close to mitochondria. Mucous cells are filled with large secretory vesicles containing thin electron‐dense filaments surrounded by electron‐lucent material in which acidic mucopolysaccharides were detected. The basal region includes the nucleus, several Golgi stacks and many dilated rough endoplasmic reticulum cisternae containing tubular structures. The granular cells are characterized by very high amounts of flat rough endoplasmic reticulum cisternae and electron‐dense spherical secretory granules containing glycoproteins. Enteroendocrine cells containing small electron‐dense granules are occasionally present in the basal region of the epithelium. Intraepithelial nerve fibres are abundant and seem to establish contacts with secretory and enteroendocrine cells.     

The ultrastructure of hemocytes inDactylopius confusus (Cockerell), and the role of granulocytes in the synthesis of cochineal dye

Summary The ultrastructural study of free circulating hemocytes in the adult cochineal scale,Dactylopius confusus (Cockerell), demonstrated five cell types: prohemocytes, typical granulocytes (T-granulocytes), oenocytoids, plasmatocytes, and granulocytes with modified sub-cellular structure to perform a special synthetic and secretory function, which we refer to as modified granulocytes (M-granulocytes). Prohemocytes showed undifferentiated sub-cellular structure of the basic stem cell type (i.e., high cytoplasmic density with numerous ribosomes, centrally located large nucleus with a distinct nucleolus, and poorly developed endoplasmic reticulum). The commonly observed typical granulocytes (T-granulocytes) had several smooth endoplasmic reticulum (SER) with dilated cisternae and many SER-derived membrane bounded granules of different sizes and electron density. Oenocytoids were identified by the presence of many crystals, RER-originated fine secretory granules, and an eccentric nucleus. Plasmatocytes were easily characterized by their variable shapes and irregular outline with pseudopodia-like cytoplasmic extensions, possession of an elongated lobed nucleus, multivesicular bodies, RER-derived membrane bounded, electron-dense, lysosomelike vacuoles, well-developed SER cisternae, and numerous pinocytic and SER-originated vesicles of different sizes along the peripheral region. M-granulocytes comprised the largest proportion of hemocytes in all samples observed. M-granulocytes were distinguished not only by the presence of membrane bounded granules of different sizes and electron density, but by the possession of large nuclei with distinct nucleoli, many mitochondria, and a highly developed network of rough endoplasmic reticulum (RER). M-granulocytes had abundant, rosette-shaped, RER-derived chains of fine secretory granules, which accumulated in the cytoplasm and vacuoles, and were ultimately deposited into the hemolymph by exocytosis. These fine granules gave a positive result with periodic acid-Schiff (PAS) test. Based on RER-synthesized fine secretory granules (M-granulocytes), their ultimate deposition into hemolymph, the red pigmentation of hemolymph, positive PAS histochemical test of these granules, and the high population of these hemocytes, no such cell type has been described in previous studies in insects. The sub-cellular structure of the granulocyte in this insect has been modified to perform a special synthetic and secretory function (i.e., possibly the synthesis of the red pigment found in hemolymph, which has been the source of commercially important cochineal dye).Abbreviations EM electron microscope - ER endoplasmic reticulum - LM light microscopy - MVB multivesicular body - PAS periodic acid-Schiff - RER rough endoplasmic reticulum - SER smooth endoplasmic reticulum - SG secretory granules - TEM transmission electron microscopy - UA uranyl acetate     

Effects of temperature on cytomorphogenesis and ultrastructure ofMicrasterias denticulata Bréb

Summary Exposure of growingMicrasterias cells to high (32°–36°C) and low (3°–10°C) temperatures produces changes in morphology that are accompanied by several ultrastructural alterations. Whereas low temperatures essentially cause simplification of cell ornamentation, a variety of cell malformations result from high temperature treatment. These are the loss of cell symmetry leading to markedly aberrant cell shapes and an increase of main lobes with reduced degree of differentiation. Preliminary studies indicate that a shift in the distribution of membrane-associated Ca²⁺ by elevated temperatures probably underlies these abnormal cytomorphogenetic events. Both, low and high temperature cause a reduction in size of the young half cell and affect cytoplasmic streaming. Moreover, nuclear migration is retarded and chloroplast arrangement is influenced by temperature treatment at both ranges. Growth velocity of primary wall responsible for cell shaping is increased at high and slowed down at low temperatures compared to cells grown at 20°C.The main ultrastructural alterations induced by high temperatures are an increase in amount and length of ER cisternae, the appearance of heat shock granule aggregations localized in the cytoplasm, a reduced number of ribosomes and polysomes, the presence of oil bodies in growing cells and a varying thickness of the primary wall. Influences of low temperatures on ultrastructure are less pronounced. They are manifested in the formation of large aggregations of ER cisternae slightly differing from those found in untreated cells, a disturbed arrangement of the microtubule system surrounding the nucleus and a decrease of the number of cell wall forming cytoplasmic vesicles.It is thought that most of the temperature effects are due to an influence on membranes probably an alteration of ionic currents and, in addition, a modulation of normal protein synthesis.Dedicated to my teacher Professor Oswald Kiermayer in deep gratitude     

Macroautophagic phenomena in renin granules

Summary The secretory granules of marine epithelioid cells take up and probably degrade mitochondria; they thus appear to have macroautophagic properties. As renin granules also have other properties uncommon for secretory granules, they are suggested to fulfill functions in these cells otherwise reserved for lysosomes.These studies were supported by the German Research Foundation within the Forschergruppe Niere/Heidelberg     

Influence of fasting and stimulation on the rat gastric endocrine cells

Summary The ultrastructure and certain cytochemical parameters of endocrine cells of the rat gastric mucosa during 168 h of fasting were investigated. To some of the fasting animals peroral food or alcohol was administered before decapitation.The EC (enterochromaffin cells) the ECL (enterochromaffin-like cells), D₁ cells, AL (A-like cells) and G cells were identified by means of electron microscopy. Only the EC, ECL, and G cells could be identified by means of light microscopy by an adequate histochemical technique.The ultrastructural picture of the ECL and of the EC cells did not change markedly during the fasting. In the D₁ cells there occurred an agglomeration of secretory granules. Some of them disintegrated and disappeared. In the AL cells an agglomeration of granules during the fasting was also observed. Granules engulfed in lysosomes were often found. The participation of lysosomes in the degradation of granules during the fasting was more marked in the AL cells than in the G cells. The participation of lysosomes was questionable in the EC and D₁ cells, and in the ECL cells no lysosomes were observed. In contradistinction to the G cells of the non-fasting animals, where more than one half of the gastrin granules were empty, the G cells during the fasting were filled with agglomerated dense granules and contained lysosomes with fragments of engulfed secretory granules.Following the administration of food (Larsen's diet) 3 h before sacrificing the dissolution of the content of granules with well preserved membranes was observed (emiocytosis did not take place). The administration of food did not lead to changes in the ultrastructural appearance of the EC cells. The peroral administration of alcohol did not lead to any changes in the ultrastructural appearance of the AL and G cells.     

Ultrastructure of STH cells of the pars distalis of castrated male mice after hepatectomy

Summary An electron microscopic study aimed at differentiation between castration gonadotrophs and posthepatectomy STH cells was performed on the pars distalis of the pituitary of castrated male mice, after partial hepatectomy. The ultrastructural features observed permit the distinction of both cell types. In the present experiments some remarkable ultrastructural changes, other than those described in a previous report, have been found in STH cells of hepatectomized mice with or without previous castration. Most of them contained masses of heterogeneous electron density, suggesting fusion of granules. These masses and some secretion granules were observed close to the plasma membrane, apparently in the process of discharging material into the pericapillary space. Granular extrusion was more frequent than normally. An increased number of lysosomes, probably related to the digestion of overproduced secretion material, was evident. The appearance of concentric lamellar formations might be related to an increase in cell movements. STH cells with severe cytoplasmic damage were also found, indicating an increased rate of cell loss.Work carried out with the financial assistance by a grant from the Comisión de Investigación Científica de la Universidad Nacional de La Plata. Thanks are due to the members of the Technical Staff of the Institute for their technical assistance.     

The fine structural localization of endogenous and exogenous peroxidase activity in human bone marrow mast cells under pathological conditions

Summary We have examined the ultrastructural characteristics of peroxidase activity in human bone marrow mast cells. These studies were performed in three patients with systemic mast cell disease, and in another six patients showing bone marrow mast cell hyperplasia. Endogenous peroxidase activity was localized in the perinuclear cisternae and strands of endoplasmic reticulum, but never in the granules. We have also demonstrated the in vivo existence of exogenous peroxidase activity in two of the three cases of systemic mast cell disease. The peroxidase internalization involved its binding to the plasma membrane, followed by its incorporation into the cell by a general endocytic process comprising the uptake of dispersed peroxidase-positive material mainly by phagocytosis of granular structures containing peroxidase. The exogenous peroxidase appeared in non-membrane bound granules, vacuoles or aggregates, but we have never seen the enzyme linked to the mast cell granules.Supported by Grants FIS 86/791 and 88/1003 from the Instituto Nacional de la Salud. Dr. Heinrichs is the recipient of FIS 88/1003 from the Instituto Nacional de la Salud     

Macromolecular differentiation of Golgi stacks in root tips ofArabidopsis andNicotiana seedlings as visualized in high pressure frozen and freeze-substituted samples

Summary The plant root tip represents a fascinating model system for studying changes in Golgi stack architecture associated with the developmental progression of meristematic cells to gravity sensing columella cells, and finally to young and old, polysaccharideslime secreting peripheral cells. To this end we have used high pressure freezing in conjunction with freeze-substitution techniques to follow developmental changes in the macromolecular organization of Golgi stacks in root tips ofArabidopsis andNicotiana. Due to the much improved structural preservation of all cells under investigation, our electron micrographs reveal both several novel structural features common to all Golgi stacks, as well as characteristic differences in morphology between Golgi stacks of different cell types.Common to all Golgi stacks are clear and discrete differences in staining patterns and width of cis, medial and trans cisternae. Cis cisternae have the widest lumina (30 nm) and are the least stained. Medial cisternae are narrower (20 nm) and filled with more darkly staining products. Most trans cisternae possess a completely collapsed lumen in their central domain, giving rise to a 4–6 nm wide dark line in cross-sectional views. Numerous vesicles associated with the cisternal margins carry a non-clathrin type of coat. A trans Golgi network with clathrin coated vesicles is associated with all Golgi stacks except those of old peripheral cells. It is easily distinguished from trans cisternae by its blebbing morphology and staining pattern. The zone of ribosome exclusion includes both the Golgi stack and the trans Golgi network.Intercisternal elements are located exclusively between trans cisternae of columella and peripheral cells, but not meristematic cells. In older peripheral cells only trans cisternae exhibit slime-related staining. Golgi stacks possessing intercisternal elements also contain parallel rows of freeze-fracture particles in their trans cisternal membranes. We propose that intercisternal elements serve as anchors of enzyme complexes involved in the synthesis of polysaccharide slime molecules to prevent the complexes from being dragged into the forming secretory vesicles by the very large slime molecules. In addition, we draw attention to the similarities in composition and apparent site of synthesis of xyloglucans and slime molecules.Dedicated to the memory of Professor Oswald Kiermayer     

Cell differentiation during early development of Nassarius reticulatus L. (Gastropoda,prosobranchia)

Summary In Nassarius reticulatus the nuclei and nucleoli undergo important morphological changes from the zygote to the 16-cell stage. In the zygote and in the trefoil (2-cell) and 4-cell stage, several agranular, fibrillar nucleolus-like bodies 1 m diameter are present in the interphase nucleus. Granular nucleoli first appear at the 8-cell stage. These nucleoli have fibrillar and granular regions. The granular regions are made up predominantly of ribosome-like osmiophilic granules. From the 16 and 32-cell stage onwards, the one or two spherical nucleoli of each nucleus measure 2.5 m in diameter and show a concentric organization with a very dense central region surrounded by a broad peripheral zone containing numerous granules, possibly of ribonucleoprotein. At the same time the number of ribosome-like particles increase in the karyoplasm and that of ribosomes in the cytoplasm. These findings are surprising because in eggs with radial cleavage, which have been subjected to more detailed analysis, the first granular nucleoli appear after the end of the cleavage, at the blastula or gastrula stage. The early appearance of granular nucleoli which seem to be characteristic of several eggs with spiral cleavage is discussed in connection with biochemical data on RNA-synthesis.This investigation was supported by the Deutsche Forschungsgemeinschaft and the Stiftung VolkswagenwerkWe wish to thank Mrs. C. Mehlis for valuable technical assistance and Prof. J. Bergerard for the excellent working conditions at the Station biologique at Roscoff (France)     

Substrate-histochemical investigations and ultrahistochemical demonstrations of acid phosphatase in larval and prepupal salivary glands of Drosophila melanogaster

Summary A major function of the larval salivary glands of Drosophila melanogaster is known to be the production of a mucopolysaccharide that serves as an adhesive during puparium formation. In order to localize the mucosubstances during development substrate histochemical methods were used, and the site of acid phosphatase was demonstrated by the ultrahistochemical lead-salt method. It could be shown that the glue-granules in the corpus cells of larval salivary glands as well as the large secretion vacuoles in the prepupal corpus cells give a positive -amylase-resistent PAS-reaction, which indicates neutral mucosubstances. Granular PAS-positive deposits in the larval and prepupal collum cells were reduced after preincubation with -amylase and may represent glycogen, which has also been seen in electron micrographs of these cells. The Hale-reaction gave a weak indication that acid mucosubstances are present in the larval glue granules and in the large prepupal secretory vacuoles. After digestion of sialic acid with -neuraminidase the weak indication was absent showing that the acid mucosubstances had been sialomucines. Ultrahistochemical demonstration of acid phosphatase indicated the presence of this enzyme in Golgi fields and lysosomal structures. Acid phosphatase seems to be missing in the large secretion vacuoles of the prepupal salivary gland.It is concluded, that the large vacuoles in the corpus cells of prepupal salivary glands represent a secretion product, obviously a mucosubstance. The lysosomal structures, containing acid phosphatase, may be accumulated in preparation for the autolysis of the gland which begins about two hours after the pupal moult, i.e. 15 hours after puparium formation.This investigation was supported by grants from the Deutsche Forschungsgemeinschaft (Ga 97/6).     

Stereological model system for free cells and base-line data for human peripheral blood-derived small t-lymphocytes

Summary T-lymphocytes derived from human peripheral blood and passed through a nylon-wool column, were employed to develop and test a new Stereological model system for free spherical cells, allowing a quantitative characterization of the cell and its components at the ultrastructural level. Electron micrographs were recorded in a hierarchical manner at three different levels of magnification and subjected to point counting procedures. The resulting parameters were expressed in relation to various reference compartments, both absolute and relative. Results indicated that the average volume of a small, non-activated T-lymphocyte was 103.8 m³, the nuclear volume 47.5 m³ and the cytoplasmic volume 55.9 m³. On the average, the cytoplasm contained 30 mitochondria, 0.7 m³ RER-cisternae, 0.2 m³ cisternae and vesicles of the Golgi apparatus and about 231,000 free ribosomes (most of them single). The ratio of eu- to heterochromatin volume was 0.5. The design and application of the Stereological model system are discussed with regard to dynamic studies of a variety of free cells, such as macrophages, neutrophilic granulocytes and various lymphocytes.

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Zusammenfassung Menschliche, in Nylonwolle gereinigte T-Lymphozyten aus dem peripheren Blut dienten als repräsentatives Untersuchungsobjekt zur Schaffung eines neuen stereologischen Modellsystems für freie, sphärische Zellen. Dieses System erlaubt, die Zelle und die darin enthaltenen Strukturkomponenten auf ultrastruktureller Ebene quantitativ zu charakterisieren.

     

Fine structural observations on magnum mucosa in quail and hen oviducts

Summary Previous investigators have reported that albuminous material in the albumin-secreting (tubular gland) cells of the magnum of hen oviduct accumulates in the ergastoplasmic cisternae and is released directly into the glandular lumen without being first concentrated into secretory granules in the Golgi region (Zeigel and Dalton, 1962). Present fine structural studies on the tubular gland cells in oviducts from actively laying wild-type Japanese quail and in an oviduct from an actively laying hen indicate that the Golgi apparatus is directly involved in the formation of secretory granules. At least three types of granules can be observed in the tubular gland cells at various times, and all types seem to be associated initially with the Golgi apparatus.In actively laying quail, the distribution of electron opaque, intermediate, and light granules within the superficial and deep regions of the glandular epithelium varies, depending on the presence of an egg in a particular region of the oviduct. Secretion of the product is merocrine, involving fusion of granule membranes with the plasmalemma of the cell surface.Granules first appear in the tubular gland cells of quail oviducts at about 4 1/2 weeks of age. The granules are of the electron opaque type and probably represent secretion in concentrated storage form. At this age, a few of the tubular gland cells exhibit distended ergastoplasmic cisternae containing material of low electron density. The appearance of these light cells, which occur with greater frequency in oviducts from older quail, probably reflects an increased level of secretory activity initiated by changes in hormonal levels. From 5 weeks of age on, intermediate and light (less concentrated) granules, as well as dark granules, are present.Supported by the National and Medical Research Councils of Canada.     

Functional differentiation of the anterior pituitary cells in the fetal pig

Summary The fetal porcine pituitary was investigated by means of ultrastructural immunocytochemistry (1) to identify the first cells synthesizing the adenohypophyseal hormones, (2) to follow their differentiation during fetal development, and (3) to compare their ultrastructural characteristics with those of mature adult cells.The first ACTH-cells, which produced and stored ACTH, -LPH, -MSH, and - and -endorphin in the same granules, were very numerous at day 34 and displayed a uniform morphology. At day 50 and thereafter, until the end of gestation, the ACTH-cells differed in their appearance probably reflecting various stages of differentiation of one cell type. The GH-cells gained rapidly ultrastructural features comparable to those of mature GH-cells. In contrast, in the case of PRL-cells, which appeared only at the end of the gestation period as immature elements containing very small secretory granules, the morphological maturation seemed to take place only after birth. The first cells synthesizing the glycoprotein hormones (LH, LH, FSH and TSH) displayed ultrastructural features of immature cells. At day 50, their ultrastructural organization started to show a different pattern. At the end of gestation, the TSH-cells and the gonadotropic cells displayed the ultrastructural features of mature cells.     

On the fine structure of the small,heavily pigmented non-pyramidal cells in lamina II and upper lamina III of the human isocortex

Summary With the aid of a newly developed technique for the successive examination of both the Golgi and pigment picture of individual neurons (Braak, 1974a) Braak (1974b) demonstrated that within lamina II and upper lamina III of the human isocortex, heavily pigmented non-pyramidal cells are distributed irregularly and sparsely. The lipofuscin pigment granules serve as excellent internal markers to identify these non-pyramidal cells in ultrathin sections. This favourable circumstance facilitates the study of these interneurons in the electron microscope.The heavily pigmented non-pyramidal cells are small, spherical to ovoid with diameters of about 12–15 m. One pole of the cell comprising a large cytoplasmic area gives rise to a few dendrites, while the other pole is occupied by the nucleus and in some cases is in close apposition to another nerve cell body. The nucleus is deeply invaginated by the large cytoplasmic area and occasionally displays nuclear inclusions. Among the usual organelles distributed within the large cytoplasmic area the mitochondria with a moderately electron dense matrix are abundant and the coarse lipofuscin pigment granules are the most striking elements. The latter contain densely packed filamentous or tubular material and a single vacuole. The perikaryon rarely receives more than 3 type I and type II synapses per section per cell, whereas the dendrites receive numerous synapses of both type I and type II. Within the apposition zone to another nerve cell body (which in no case is a heavily pigmented non-pyramidal cell) puncta adhaerentia occur and also contacts in which the cleft of 8 nm is intersected by a dense stratum.Some of the ultrastructural findings are summarized in the schematic drawing of Figure 15.     

Ultrastructural localization of thyrotropin (TSH) in the porcine anterior pituitary

Summary Two different immunocytochemical techniques based on specific antibodies against -subunits of porcine, rat and bovine TSH were applied at the ultrastructural level to identify the TSH cells in the porcine anterior pituitary and to compare the subcellular localization of the hormone.The post-embedding method on serial ultrathin sections revealed the localization of TSH in the granules of a specific cell type, negative for the other hormones. TSH was found in polyhedral cells characterized (i) by their content of granules that were the smallest of all the cell types examined, and (ii) by their flattened or slightly dilated RER cisternae. The pre-embedding method applied to isolated cells permitted a good penetration of antisera and the maintenance of antigenicity in sites inaccessible to the post-embedding method. Thus, immunoreactivity of TSH was detected in the secretory granules, the cytoplasmic matrix and in portions of the rough endoplasmic reticulum, in association with some membranes and inside some saccular structures.