Microvasculature of the human testis and excurrent duct system

Summary The vascular microarchitecture of the human testis and excurrent duct system was examined by use of a casting method combined with scanning electron microscopy. In the testicular parenchyma, the capillaries form a fine plexus around the seminiferous tubules. The commonly described rope-ladder-like pattern of the peritubular capillaries is absent in the human testis. The microvasculature of the rete testis consists of a poorly organized plexus. Throughout the epididymis including the ductuli efferentes, the peritubular capillary network encircles each tubule cylindrically. In the cauda epididymidis, a coarse venous network surrounds the capillary network externally. Small arteries of the epididymis not only penetrate the connective tissue septa, but also run along the surface. In the ductus deferens, three distinct microvascular systems are distinguished: (1) a venous network located in the connective tissue surrounding the muscular coat, (2) a microvascular plexus within the muscular coat, and (3) a peritubular capillary network. The plexus within the muscular coat interconnects the venous and the peritubular capillary networks.     

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.     

Actin-like filaments in the myoid cell of the testis

Microfilaments in the myoid cells of the peritubular tissue in the mouse, swine and human testis bind heavy meromyosin (HMM) and form arrowhead complexes. The periodicity of the arrowhead complexes is about 35 nm. Individual filaments show arrowheads that point in the same direction. Opposing polarity of the HMM-bound filaments is also observed. The microfilaments do not bind HMM in the presence of 10 mM ATP. After treatment with the contraction medium of Hoffmann-Berling, the filaments appear to be undulated. These observations indicate that the microfilaments in the myoid cell are actin-like in nature. A small number of thicker filaments (about 10 nm in diameter) which do not bind HMM is also observed in the cell. Microfibrils which have been reported around the human myoid cell are also found in the swine.     

On the fine structure of the external glial layer in the isocortex of man

Summary The surface of the external glial layer of the isocortex in the human temporal lobe is generally slightly undulated, with a few protrusions and indentations. The surface is formed by an uninterrupted basement membrane which is continuous over the surface no matter how tortuous it becomes. The overall thickness of the glial layer is generally 15 to 25 m, but diminishes to about 5 m immediately beneath blood vessels. It consists mainly of a variable number of stacked glial cell processes.Two groups of cell bodies are encountered particularly in the middle and lower levels of the glial layer. Most of the cells are specialized fibrous astrocytes. They are characterized by eccentrically placed, rounded nuclei with homogeneously dispersed chromatin, and electron-lucent cytoplasm rich in filaments. Lipofuscin pigment granules occupy large areas of the perikaryon. The astroglial cells give rise to four types of processes: foot-processes, tangential and radial processes, and processes irregular in outline.The foot-processes ascend towards the cortical surface and terminate as flat expansions spreading out immediately beneath the basement membrane. Contiguous terminal expansions are connected by gap junctions. The individual profiles are irregular in form and fit together like in a jig-saw puzzle. The plasmalemma beneath the basement membrane is underlined by a fuzzy material, which is penetrated by glial filaments. In the terminal expansions individual or groups of mitochondria are abundant.The tangential processes are straight and slender and form a lattice within the middle and deep level of the external glial layer. They contain numerous filaments, evenly distributed or fasciculated. The remainder of the lattice is filled up by a considerable number of processes irregular in outline and varying greatly in size. They contain fewer filaments than the tangential processes, coursing in all directions, and glycogen particles. In both types of processes only a few mitochondria are present. These processes are also connected by gap junctions and desmosomes, too.Large cytoplasmic areas of astroglial cells localized in the deepest portion of the glial layer protrude into the neuropil of the molecular layer, giving rise to several radiate processes, which extend deeper into the cortex.The second, heterogeneous group of cell bodies is characterized by elongated nuclei, ovoid or irregular in outline, which are smaller than those of astroglial cells, and contain blocks of condensed chromatin; a thin cytoplasmic rim generating a few appendages surrounds the nucleus. The first sub-type is characterized by a nucleus with large chromatin blocks bordering the inner nuclear membrane and a medium-dense cytoplasmic matrix. The second sub-type displays smaller chromatin condensations at the inner nuclear membrane and many microtubules are scattered throughout an electron-lucent cytoplasm.     

Immunohistochemical distribution of sulfhydryl oxidase in the human testis

Summary Sulfhydryl oxidase (SOx) is an enzyme that catalyzes the oxidation of sulfhydryl compounds. It is present in mitochondria of certain testicular cells at specific stages of functional activation. In the mature human testis moderate SOx immunoreactivity is found in Leydig cells, and lacking in Sertoli and in peritubular cells. The A_dark spermatogonia usually contain immuno-reactive mitochondria, while in A_pale spermatogonia immunoreactivity is mostly low. In stage V of spermatogenesis, A_pale spermatogonia were found containing immunoreactive material. Leptotene (stages IV and V) and zygotene (stage VI) primary spermatocytes display a moderate immunoreaction. It is strongest in pachytene spermatocytes of stages I–IV, decreases in stage V, and is low during diakinesis and in secondary spermatocytes. Late spermatids usually show a stronger immunoreactivity than early spermatids. At stage V of spermatogenesis the late spermatids contain only few immunoreactive particles. Spermatozoa are free of SOx-immunoreactive mitochondria. In residual bodies small amounts of SOx-immunoreactive particles are seen. Compared to rat and hamster testis, SOx immunoreactivity of the human testis is less clearly stage-dependent and it is not confined to certain germ cell stages. As deduced from the findings in patients with spermatogenic disorders, the SOx immunoreactivity of spermatogonia in human testis seems to be of diagnostic relevance.     

Multinucleate Sertoli cells in aged human testis

Summary The present investigation documents morphological characteristics of human Sertoli cells of aged males. Testicular material was obtained from 35 patients (age 62–84 years) with carcinoma of the prostate who had received no previous anticancer therapy. As revealed by light and electron microscopy the appearance of the germinal epithelium showed great individual variations. In all cases examined, however, the occurrence of multinucleate Sertoli cells was a common finding. In seminiferous tubules with intact spermatogenesis these cells closely resembled the normally occurring variants, whereas they displayed features reminiscent of immaturity in the absence of germ cells. It is hypothesized that the nuclei of Sertoli cells in the special situation of aging may resume the capacity to divide, an ability normally restricted to immature cells. Thus, mitosis without subsequent cytokinesis might be an explanation for the formation of multinucleate Sertoli cells.The authors wish to thank Dr. R. Hubmann, Hamburg, for kindly supplying the testicular material. The excellent technical assistance of Mrs. E. Roosen-Runge, Mrs. E. Schäfer, and Mrs. A. Stromeyer is gratefully acknowledgedSupported by grants from the Deutsche ForschungsgemeinschaftPresented in part at the Kleinkonferenz der Deutschen Forschungsgemeinschaft, Schloß Auel, October 3–5, 1980     

Centrioles and associated striated filamentous bundles in rabbit pulmonary lymphatic endothelial cells

Summary An electron microscopic study of the pulmonary lymphatic collecting channels and their valves in the rabbit revealed that the endothelial cells generally contain two centrioles which are almost invariably associated with one to several striated bundles of filaments. The structure of the centrioles corresponds well with that in other cell types. The filaments however were present only in endothelial cells and not in the perilymphatic connective tissue cells. The bundles consist of 2 to 6 filaments of about 40 Å diamenter and show a cross banding with a periodicity of 600 to 900 Å. They are attached at both ends or in the middle of the centriole. Their function is unknown, but they might be vestigial rootlets of rudimentary cilia of lymphatic endothelial cells.This study has been supported by a grant from The Council for Tobacco Research—U.S.A.. We thank R. Janssens for technical, G. Pison and St. Ons for photographic and R. Kell for secretarial assistance.     

Changes in the fine structure of venous endothelium in the rabbit following adrenaline infusion

Summary The fine structure of the endothelium lining the femoral and mesenteric veins in the rabbit was examined following the infusion of concentrations of adrenaline varying from 0.5 to 5.0 g/kg. Control animals were infused with saline.Vesiculation of the endothelial cells was observed following each infusion of adrenaline, the effect being most marked with the highest dose used. It is suggested that this vesiculation may be associated with the release of antihaemophilic globulin and/or plasminogen activator from the endothelial cells.The authors wish to express their gratitude to Mrs. M. Woodford, Miss. G. Moore and Mr. R. Ellis for their skilful technical assistance     

The fine structure of the newborn rat adrenal cortex

Summary The structural changes of the zona juxtamedullaris of the rat adrenal cortex at birth, have been examined by the light and the electron microscope. In this zone clusters of medullary cells lying among the strands of cortical tissue were observed. In the inner portion of the zona juxtamedullaris two types of adrenocortical cells were found: light and very-dark cells. The latter are smaller than the light cells and are always in close connection with the medullary tissue. The ultrastructural features of the very-dark cells suggest that these elements are in degeneration. This finding supports the hypothesis that at birth there is a partial degeneration of the rat zona juxtamedullaris, i.e. the zone corresponding to the fetal zone of some mammalian species.It is proposed that in all mammalian species at birth there is a partial regression of the zona juxtamedullaris and that the regression of the fetal zone is only the quantitative increase of this phenomenon. This hypothesis is discussed in relation to numerous data demonstrating that there are enzymatic conditions in the rat during fetal life, which permit a discrete hypertrophy of the adrenal cortex.The author wishes to express his appreciation to Dr. A. Gambino and to Mr. G. Gottardo for technical assistance.     

The fine structure of the female reproductive system of Zorotypus caudelli Karny (Zoraptera)

The general structure of the female genital system of Zorotypus caudelli is described. The ovarioles are of the panoistic type. Due to the reduction of the envelope (tunica externa) the ovarioles are in direct contact with the hemolymph like in some other insect groups, Plecoptera included. The calices are much larger in Z. caudelli then in Zorotypus hubbardi and their epithelial cells produce large amounts of secretions, probably protecting the surface of the eggs deposited on the substrate. Eggs taken from the calyx bear a series of long fringes, which are missing in the eggs found in the ovariole, and in other zorapteran species. The long sperm of Z. caudelli and the long spermathecal duct are likely related to a sexual isolating mechanism (cryptic female choice), impeding female re-mating. The apical receptacle and the spermathecal duct - both of ectodermal origin - consist of three cell types. In addition to the cells beneath the cuticle lining the lumen, two other cell types are visible: secretory and canal cells. The cytoplasm of the former is rich in rough endoplasmic reticulum cisterns and Golgi complexes, which produce numerous discrete dense secretory bodies. These products are released into the receiving canal crossing the extracellular cavity of secretory cells, extending over a series of long microvilli. The secretion is transported towards the lumen of the apical receptacle of the spermatheca or to that of the spermathecal duct by a connecting canal formed by the canal cells. It is enriched by material produced by the slender canal cells. Before mating, the sperm cells are enveloped by a thick glycocalyx produced at the level of the male accessory glands, but it is absent when they have reached the apical receptacle, and also in the spermathecal duct lumen. It is likely removed by secretions of the spermatheca. The eggs are fertilized at the level of the common oviduct where the spermathecal duct opens. Two micropyles at the dorsal side of the equator level possibly facilitate fertilization. The presence of these two micropyles is a presumably derived feature shared with Phasmatodea. The fine structure of the female reproductive system of Z. caudelli does not allow to assess the phylogenetic position at the present stage of knowledge. The enlarged calyx and the temporary presence of long fringes on the eggs are potential autapomorphies of Z. caudelli or may indicate relationships with other Zorotypus species.     

Structure of sinuses in the human lymph node

Summary A casting technique has been employed to display in three dimensions, the lymphatic microcirculation within the human lymph node. The casting compound filled the marginal sinus, and diffusely permeated the cortical lymphoid parenchyma. However, deep within the lymph node in the medullary region, the medium remained within the limits of the sinus walls. The casts showed well-defined channels appearing similar to vessels. These converged into larger vessels, which drained into efferent lymphatics leaving the node at the hilus.Electron microscopic examination showed that the outer wall of the marginal sinus and the trabecular side of trabecular sinuses had an intact, continuous endothelium with a basement membrane. However, gaps were present in the inner wall of the marginal sinus, as well as in the parenchymal wall of the trabecular sinus. In the medulla, the sinuses were lined by endothelial cells which appeared similar to macrophages. The sinus lining was incomplete and possessed numerous perforations. These observations indicated that sinus walls adjacent to connective tissue served as a barrier to cell movement, but those adjacent to a large lymphoid cell population had gaps, with cells in apparent transit between sinus lumen and parenchyma.     

On the fine structure of polyribosomes

Cell and Tissue Research - The ultrastructural morphology of ribosomes was studied in tissue sections of rat uterus using different fixatives (acrolein, formaldehyde, acetic acid, methanol-acetic...     

Studies of the fine structure of ovarian interstitial tissue

Summary The post-natal evolution of thecal gland in the domestic fowl has been explored, and a hypothesis for this development is proposed. It is suggested that the surface epithelium of the ovary forms crypts and submicroscopic clefts (ingrowing cords) which contribute with epithelial elements required for the regeneration of some of the ovarian elements, including the thecal glands. Complexes of these ingrowing epithelial cells are forming small islets which, after hormonal stimulation, are transformed into well defined structures, the thecal glands, with a specific function, viz. steroid bio-synthesis.     

Quantitative electron microscopy of endocrine cells in oxyntic mucosa of normal human stomach

Summary An ultrastructural morphometric study of the endocrine cells of the oxyntic mucosa of the stomach in gastric biopsies collected from five male and five female healthy volunteers aged 19–31 was performed. No sex-related differences were disclosed. Endocrine cells accounted for 1.2±0.4% of the epithelial volume and 0.9±0.4% of the mucosal volume, i.e., including the lamina propria. After classification of the specific endocrine cell types according to the ultrastructural morphology of secretory granules, the volume densities of ECL, P and D cells (30±9%, 24±7%, and 22±4% of the entire endocrine cell mass, respectively) were higher than those of other endocrine cell types. In particular, EC cells contributed less than 10% and X cells represented a very low proportion of the total cells. Non-granulated profiles of cells which in all other respects appeared to be endocrine were also found with a volume density of 8±4%. D cells were distinguished by the high fraction of cytoplasm occupied by secretory granules (31±5%). Subdivision of the whole mucosa into four horizontal segments revealed the endocrine cells to be mostly distributed in the three lower, with virtually no endocrine cells in the superficial segment. The quantitative ultrastructural analysis of the endocrine cell population of the normal human oxyntic mucosa provided by this study may allow a better evaluation of physiological and pharmacological variations of the endocrine cell population.     

An electron microscopic study of non-fixed and non-dehydrated normal human stratum corneum

Summary This is an electron microscopic study of non-fixed and non-dehydrated normal human stratum corneum from the lumbar region.Non-stained sections have a low contrast. In sections examined 3 days after skin biopsy the cytoplasm of the cells shows a uniform contrast or exhibits dark and light areas. A single layer delimits the cytoplasm from the intercellular space. The latter is partly filled out with substance.In sections stained 2 to 4 days after skin biopsy the fibrils are distinct. On the basis of the variations in their opacity and ultrastructure three types of horny cells are clearly distinguishable. In cells of type 1 intensely stained keratohyalin and less opaque fibrillar substance occur. A distinct keratin pattern is not found. In cells of type 2 the fibrils show areas with distinct kerytohyalin and keratin pattern and transitional phases between these two stages of fibrillar differentiation. The keratin pattern representing the final stage of the fibrillar differentiation process is visualized through a successive discoloration of the filaments, whereas the interfilamentous substance retains the opacity of the keratohyalin. In cells of type 3 the entire fibrillar substance exhibits a keratin pattern. This consists of less opaque filaments with a diameter of 74 Å. The septa representing the interfilamentous substance are estimated as 30 Å at their thinnest points. These observations of the fibrils are completely comparable to the findings in fixed and dehydrated normal human stratum corneum.In sections stained particularly more than 18 days after skin biopsy the fibrils exhibit pronounced changes in their staining properties with concomitant decrease in distinctness or a complete extinction of the keratin pattern.The observations of the modified plasma membrane and the intercellular space in stained sections correspond to the findings in fixed and dehydrated normal human stratum corneum. The modified plasma membrane and the structures in the intercellular space appear with equal distinctness, whether the sections are stained 2 to 4, 6 to 12 or 14 to 21 days after skin biopsy.This investigation was supported by grants from the Edvard Welander Foundation and from the Swedish Medical Research Council (B71-12X-2708-03).     

Harderian glands in mice: Fluorescence,peroxidase activity and fine structure

The Harderian glands of albino mice are composed of tubulo-alveoli which contain two secretory cell types. The most common cell (type A) displayed a natural red fluorescence due to the presence of porphyrins. Lipid droplets in this cell and along its apical border were often intensely fluorescent. The less common cell (type B) did not fluoresce. The type B cell contained unusual lipid droplets surrounded by concentric layers of membranes, and sometimes displayed cylindrical organelles believed to be associated with the formation of pigment. A dense red-brown pigment was observed in the lumens of a few tubulo-alveoli and it did not fluoresce, but areas where pigment formation was taking place fluoresced brightly. Myoepithelial cells, containing thick and thin filaments, were found underlying both secretory cell types. Fenestrated capillaries and adrenergic and cholinergic nerve endings were abundant in the adjacent connective tissue. Endogenous peroxidase activity was identified in both secretory cell types and was found localized only within tubules and vesicles of the smooth endoplasmic reticulum.     

Effect of colchicine on the fine structure of the neuromuscular junction

Summary Repeated injections of colchicine into the forearms of normal adult newts led to the disappearance of microtubules within some nerves and a concomitant loss of specialized morphological features at the neuromuscular junction. Within 2 weeks, the postsynaptic folds decreased in height and number, became flattened and eventually disappeared. In addition, nerve terminals in drug-treated animals became separated from the muscle surface and were highly congested with masses of synaptic vesicles. The present findings show that colchicine has an effect on the structural integrity of the neuromuscular junction. These effects could be direct; secondary to retraction of the nerve from the muscle surface; or the result of interference with the proper transport and/or release of neurotrophic substances.Supported by grants from the National Science Foundation (GB 20902) and from the National Institute of General Medical Sciences (TIGM-00105) and the National Cancer Institute (TICA-05055), National Institutes of Health, United States Public Health Service.     

Effect of cycloheximide on the fine structure of corpus luteum in intact and hypophysectomized rats

Summary In rats, one large intravenous dose of cycloheximide leads to extensive development of two types of membrane-formations in the cells of corpora lutea, within two hours. Both the laminated dense bodies (concentric layers of smooth membranes showing high electron density) and the tubular aggregates (tightly packed smooth tubules with diameter smaller than usual) exhibited obvious connections with endoplasmic reticulum membranes. The reorganization of tubular aggregates gave rise to crystalloids showing hexagonal symmetry. The crystalloids, being obviously unstable, were transformed into smooth fingerprints (concentric arrays of paired agranular membranes showing the same density as endoplasmic reticulum membranes). Hypophysectomy, performed 24 hours previously, moderated but did not totally abolish the development of membranous configurations. The described effect of cycloheximide is considered to represent cellular injury, probably due to membrane-denaturation.This work was supported in part by the Medical Research Council of Canada (Block Term Grant MT-1829), the Ministère des Affaires Sociales, Quebec, and Succession J.A. DeSève. The authors thank the Upjohn Company, Kalamazoo, Michigan, U.S.A., for the cycloheximide used in these experiments.Fellow of the Medical Research Council of Canada.