A comparative study on the innervation and the vascularization of the bulbus arteriosus in teleost fish

Summary The structure of the bulbus arteriosus of a wide range of teleost fish is described with particular reference to the vascularization and innervation. The adventitia of the organ consists of blood vessels and large nerve bundles in a collagen matrix. The nerve bundles contain monoamines, and fluorescence studies show small terminal bundles penetrating the muscular media; this is confirmed by electron microscopy. The media consists of an extensive elastic tissue matrix with a spiral arrangement of smooth muscle cells joined end to end by desmosomes and presumed electrotonic junctions. The muscle cells are innervated only at the adventitia/media boundary and the significance of this innervation is discussed. It is proposed that there is a correlation between the degree of vascularization and innervation and the activity of a particular species offish.     

A light and electron microscopic study of he heart of a crayfish, Procambarus clarkii (Giraud). II. Fine structure

The adventitia of the crayfish heart is composed of cells that are separated from each other by an intercellular space about 280 Å wide. Desmosomes are present on apposing surfaces of adjacent cells. A basal lamina underlies the adventitia and consists of a dense, amorphous substance that contains numerous fine filaments. The myocardial cells are striated and an external lamina 0.1 μ thick is present on the surface of the plasma membrane. The nuclei and most of the cytoplasm, glycogen and mitochondria are located at the cell periphery. The myofibrils are composed of thick and thin filaments and confined to the core of the cell. A T system and a well-developed SR are present. Elements of these organelles form dyads at levels that correspond to the H bands, and triads at levels that correspond to the Z bands of the peripheral myofibrils. The relationship of the T tubules to the myofibrils is discussed. Locus cells exhibit a unique pattern of intracellular myofibrillar branching. They branch from a region which has a structure similar to the Z band material. The myofibrils radiate outwardly in various directions and form numerous cellular branches which form intercalated discs with adjacent myocardial cells. These discs are more complex than those observed in poikilothermic vertebrates but are simpler than those in mammals. An endocardium is lacking in the crayfish heart but interstitial cells are present in close association with the myocardial cells and neural elements. Terminal nerve processes deeply embedded in the myocardial cells are described.     

Ultrastructural analysis of the morphology and function of the spermatheca of the pulmonate snail,Sonorella santaritana

The ultrastructure of the spermatheca of the reproductive tract in the pulmonate snail, Sonorella santaritana, was investigated. This organ has a debris-filled lumen and an outer wall which can be divided into three distinct layers. The cell layer adjacent to the lumen is comprised of two cell types, tall columnar epithelial cells with microvilli and cells lacking microvilli. The next layer also has two cell types, muscle cells and apparent pigment cells. The most distant layer is an adventitia of large glycogen-containing cells. The lumen of the spermatheca contains a core of partially digested sperm and related materials. The luminal contents and the cellular morphology of this organ suggest that the spermathecal functions are both digestive and absorptive. It is proposed that excess sperm and related materials are transported to the spermatheca, digested, and the usable products are reabsorbed.     

脉红螺消化系统的形态学研究

脉红螺消化系统由十二个器官组成。其消化管壁都由粘膜层、粘膜下层、肌层和外膜四层结构构成。作者对消化腺的细胞进行了较详细的描述,并利用组化方法测定消化腺细胞中含有的酶类。作者还对部分器官的超微结构进行了观察。     

丹顶鹤胆囊的显微观察

应用光镜及透射电镜观察一例成体雄性丹顶鹤胆囊。结果表明,丹顶鹤胆囊粘粘膜、肌层和外膜三部分组成。粘膜上皮高柱状、游离端有密集排列的微绒毛,胞质面端有许多粘液颗粒,说明上皮细胞具有吸收功能并可分泌粘液。     

Selective isolation of rat aortic wall layers and their cell types in culture—Application to converting enzyme activity measurement

The rat aorta, whose three wall layers can be separated by microdissection offers the rare possibility of comparing physiological characteristics of in vivo tissular cell components and corresponding cells after culture.We developed a technique allowing the dissociation of the three tunicae (intima, media and adventitia) of the rat aorta and the culture of their main cell types i.e: endothelial cells (EC) from intima, smooth muscle cells (SMC) from media and fibroblasts (Fib) from adventitia. Comparison between selected tunicae in vivo and their corresponding cells in vitro was performed via arterial angiotensin converting enzyme (ACE) activity measurements in Wistar rats.In vivo microsomial ACE activity for each tunica was as follows: 368.9 ± 34.3 (endothelium), 10.5 ± 1.9 (media) and 10.2 ± 4.9 (adventitia) pmol/mg protein/min. Corresponding cell primary culture values were 1.2 ± 0.1 (EC), 0.06 ± 0.02 (SMC) and 0.24 ± 0.01 (Fib) pmol/mg protein/min. Incubation of serum-deprived cells with Dexamethasone (10⁻⁷M) over 48 hr induced a statistically significant shift of total ACE activity from controls to stimulated cells of 2.9 ± 0.3 to 9.7 ± 1.0 in EC, 0.8 ± 0.1 to 32.1 ± 4.9 in SMC and 1.03 ± 0.65 to 57.2 ± 2.1 pmol/ mg prot/min in fibroblasts.In the rat aorta, ACE was present not only in the intimal endothelial cell lining, but also in the media and the adventitia. ACE activity levels in primary cultured vascular cells were about 100-fold less than those found in the ex vivo tissues. Nevertheless, ACE expression seems to be more constitutive in endothelial cells and more inducible in smooth muscle cells and fibroblasts. This methodological approach should be of interest in studying environmental or genetic regulation of protein expression in the three layers/three cell types of the vascular wall.     

THE STRIATED MUSCULATURE OF BLOOD VESSELS : II. Cell Interconnections and Cell Surface

The interconnections and the surfaces of the striated muscle cells which occur in thoracic and in lung veins of the mouse were studied with the electron microscope. The osmium-fixed tissues were embedded in methacrylate or in araldite and sectioned with a Porter-Blum microtome. Many preparations were stained before embedding with phosphotungstic acid or after sectioning with uranyl acetate. Typical intercalated discs are observed in this muscle. They are similar to the discs found in heart muscle. These intercalated discs represent boundaries between separate muscle cells. Along the discs, cells are joined in planes normal to their myofilaments. The same cells are also joined in planes parallel to the myofilaments by means of lateral interconnections. These lateral cell boundaries are in continuity with the intercalated discs. Three morphologically distinct parts occur within the lateral cell interconnections: One is characterized by small vesicles along the plasma membrane, the second part has the structure of desmosomes, and a third part represents an external compound membrane (formed by the two plasma membranes of the adjoining cells) and is termed "quintuple-layered cell interconnection." Small vesicles and plasma membrane enfoldings along the free surface of muscle cells are interpreted as products of a pinocytosis (phagocytosis) process. Some of them are seen to contain small membrane-bounded bodies or granules. The free cell surface shows a characteristic outer dense layer ("basement membrane") which accompanies the plasma membrane. The topographic relation of this dense layer with the plasma membrane seems to vary in different preparations. The significance of this variation is not well understood. On two occasions a typical arrangement o vesicles and tubules was observed at Z band levels, just beneath the plasma membrane. These structures are believed to represent endoplasmic reticulum. Their possible significance for the conduction of excitation is discussed.     

The suspensory muscle of the duodenum

The suspensory muscle of the duodenum continues the muscular layers of the duodenum, which is consequently surrounded on its mesenteric border only by the muscularis mucosae. Between the muscle bundles of the suspensor there is much loose connective and adipose tissue. Microganglions of no more than 90 cells may be found between the muscle bundles of the suspensor. In their superior part, the muscle bundles have connective sheaths, which are continuous with the adventitia of the aorta and celiac trunk. It is most probable that the suspensor acts like a sphincter and is innervated contrarily to the duodenum.     

Ultrastructure of atrial and ventricular myocardium in the pike Esox lucius L. and mackerel Scomber scombrus L. (Pisces)

Summary Atrial and ventricular muscle in the pike and mackerel hearts consists of narrow, branching cells. The atrial cells in the two species are similar whereas the ventricular cells differ. The sarcolemma is attached to the Z and M lines of the sarcomere. Intercalated discs are common, and the transverse parts display desmosomes and intermediate junctions. Nexuses are uncommon and only occur in the longitudinal parts of the intercalated discs. The sarcoplasmic reticulum forms a regular hexagonal network on the myofibrillar surface. Subsarcolemmal cisternae form peripheral couplings at the I-A level. Junctional processes are usually inconspicuous, but an electron dense substance is present between the sarcolemma and the Junctional sarcoplasmic reticulum. Specific heart granules are common in atrial cells of both species and in ventricular cells of the pike, but are very scarce in mackerel ventricular muscle.This work was supported by grants from the Norwegian Research Council for Sciences and the Humanities     

东方铃蟾消化道组织学的初步研究

采用组织学方法对东方铃蟾的消化道进行了研究。结果表明:肠分为十二指肠、空肠和大肠。消化道管壁由粘膜层、粘膜下层、肌层和浆膜层构成。食道、胃和肠均为单层柱状上皮。胃和十二指肠的粘膜皱褶最丰富。食道腺为复泡状腺,胃腺属于单管状腺,肠的各段无多细胞腺体,但空肠和大肠有丰富的杯状细胞。肌层均为平滑肌,内层环肌较厚,外侧纵肌较薄,其中大肠的外侧纵肌最发达。     

Diurnal fluid expression and activity of intervertebral disc cells

The intervertebral discs are large cartilaginous structures situated between the vertebral bodies, occupying around one third of the length of the spinal column. They act as the joints of the spine and carry mechanical load arising from body weight and muscle activity. Loads change with every alteration of posture and activity and the discs thus undergo a diurnal loading pattern with high loads on the discs during the day's activity and low loads on it at night during rest. As the disc is an osmotic system, around 25% of the disc's fluid is expressed and re-imbibed during each diurnal cycle with consequent changes in the osmotic environment of the disc cells. Here, present information on the effect of osmotic changes in disc cell metabolism is reviewed; results indicate that prevailing osmolarity is a powerful regulator of disc cell activity.     

Ultrastructure of the aortic diverticula of the adult dragonfly Sympetrum danae (Odonata: anisoptera)

Summary The aorta of Sympetrum danae possesses two dorsal diverticula: one in the mesothorax and one in the metathorax. They are very similar in form and position. Each diverticulum has a dorsal valve through which blood is pumped from the wings down into the aorta. The wall of the aortic diverticula consists of two simple cell layers: an outer epidermis-like layer and an inner muscle layer. The nuclei of the muscle cells are situated close to the lumen of the diverticula. The mitochondria are evenly dispersed between the myofibrils and are often paired up on either side of the Z-band. The Z-bands are thick and fragmented. The length of the sarcomeres varies from 3.3 to 6.1 . The A-band length is about 3 . The myofibrils consist of thick (250 Å) and thin (85 Å) filaments. Each thick filament is surrounded by 9–12 thin filaments. The sarcoplasmic reticulum is well developed and separates the myofibrils with one or two layers. The T-tubules are flattened and branch irregularly like a two-dimensional tree between the lamellar myofibrils. Intercalated discs are observed.The peculiarities of the muscle of aortic diverticula in S. danae are discussed in relation to various muscles of other insects and arthropods.     

STUDIES ON BLOOD CAPILLARIES : I. General Organization of Blood Capillaries in Muscle

The wall of the blood capillaries of skeletal muscles (diaphragm, tongue, hind legs) and myocardium of the rat, guinea pig, and hamster consists of three consecutive layers or tunics: the endothelium (inner layer), the basement membrane with its associated pericytes (middle layer), and the adventitia (outer layer). The flattened cells of the endothelium have a characteristic, large population of cytoplasmic vesicles which, within the attenuated periphery of the cells, may attain a maximum frequency of 120/µ² of cell front and occupy ~18% of the cytoplasmic volume; these values decrease as the cells thicken toward the perikaryon. The vesicles are 650–750 A in over-all diameter and are bounded by typical unit membranes. They occur as single units or are fused to form short chains of two to three vesicles. Each configuration may lie entirely within the cytoplasm or open onto the cell surface. In the latter case, the unit membrane of the vesicle is continuous, layer by layer, with the plasmalemma. Chains of vesicles opening simultaneously on both the blood and tissue fronts of the endothelial tunic have not been observed either in sections or in a tridimensional reconstruction of a sector of endothelial cell cytoplasm. Adjacent endothelial cells are closely apposed to one another and appear to be joined over a large part of their margins, possibly over their entire perimeter, by narrow belts of membrane fusion (zonulae occludentes). Except for tongue capillaries, patent intercellular gaps are rare or absent. The middle layer is formed by a continuous basement membrane (~500 A thick) and by pericytes which lie in between leaflets of this membrane. The tips of the pericyte pseudopodia penetrate through the inner leaflet of the basement membrane and join the endothelium in maculae occludentes. The adventitia is a discontinuous layer comprising cellular (macrophages, fibroblasts, mast cells) and extracellular (fibrils, amorphous matrix) elements. The same general type of construction appears to be used along the entire length of the capillary.     

Isolation of Blood-vessel-derived Multipotent Precursors from Human Skeletal Muscle

Since the discovery of mesenchymal stem/stromal cells (MSCs), the native identity and localization of MSCs have been obscured by their retrospective isolation in culture. Recently, using fluorescence-activated cell sorting (FACS), we and other researchers prospectively identified and purified three subpopulations of multipotent precursor cells associated with the vasculature of human skeletal muscle. These three cell populations: myogenic endothelial cells (MECs), pericytes (PCs), and adventitial cells (ACs), are localized respectively to the three structural layers of blood vessels: intima, media, and adventitia. All of these human blood-vessel-derived stem cell (hBVSC) populations not only express classic MSC markers but also possess mesodermal developmental potentials similar to typical MSCs. Previously, MECs, PCs, and ACs have been isolated through distinct protocols and subsequently characterized in separate studies. The current isolation protocol, through modifications to the isolation process and adjustments in the selective cell surface markers, allows us to simultaneously purify all three hBVSC subpopulations by FACS from a single human muscle biopsy. This new method will not only streamline the isolation of multiple BVSC subpopulations but also facilitate future clinical applications of hBVSCs for distinct therapeutic purposes.     

An SEM study of cellular morphology,contact, and arrangement,as related to gastrulation inXenopus laevis

Summary Cellular morphology, contact, and arrangement in the late blastula and in various stages of gastrulation ofXenopus were examined by SEM of specimens dissected after fixation or fractured in amyl acetate. The prospective ectoderm of the blastocoel roof consists of several layers of interdigitating cells connected by numerous small protrusions which may function in the decrease in number of cell layers observed during ectodermal epiboly. During gastrulation, prospective mesoderm is regionally differentiated by cellular morphology and arrangement into preinvolution mesoderm, the mesodermal involution zone, and involuted mesoderm. The involuted anterodorsal (head), lateral, and ventral mesoderm consists of a stream of loosely-packed, irregularly shaped cells having large extensions of the cell body attached locally to other cells by small protrusions. Involuted posterodorsal mesoderm (chordamesoderm) consists of elongated cells arranged in palisade fashion and connected by similar protrusions. Involuted mesodermal cells in all regions are attached to the overlying prospective ectodermal cells by numerous small protrusions along the entire interface between the two cell layers. Suprablastoporal endodermal cells involute as an epithelial sheet, changing in shape in the process, to form the roof of the archenteron. Bottle cell morphology, arrangement, and position with respect to the mesodermal cell stream is described. Evidence presented here and elsewhere suggests that involution of mesoderm and of the archenteron roof inXenopus is dependent primarily upon the relative movement of the mesodermal cell stream and of the overlying ectoderm.     

Histology of the esophagus of the adult frog Rana perezi (Anura: Ranidae).

Study of the esophageal microscopic morphology of adult Rana perezi by light and electron microscopy discloses some large folds throughout the esophagus that are in themselves ringed. Glandular ostia open in the furrows of the luminal surface. The esophageal wall is made up of a connective adventitia rich in melanocytes, a muscular tunica, a connective and glandular subepithelial layer, and a pseudostratified ciliated epithelium. This epithelium basically consists of ciliated, goblet, basal, microvillous-apex, and migratory cells. Two types of goblet cells are distinguished with regard to the granular ultrastructure. The microvillous-apex cell has not been found in other amphibians. It shows a very differentiated morphology with a high number of mitochondria. The basal cells give the epithelium a pseudostratified morphology, and they have a proliferative function. Glands are branched and drain through an excretory duct that has a monolayered mucosecreting epithelium. The glandular units are formed by two principal types of cells: mucosecretory and serous.     

Primary cultures of enzyme-isolated cells from normal and atherosclerotic human aorta

A technique has been developed for isolating cells from the intimal and medial layers of the human aorta by enzymatic dispersion. After mechanical separation of intima, media and adventitia the intima and the media were dispersed by collagenase and elastase. Enzyme-isolated cells seeded in the culture with at a frequency of 30 to 50%. In the primary culture differentiated aortic cells were morphologically heterogenous. It was possible to define four main types of cells according to their shape: polygonal, elongated, asymmetrical and stellate. Polygonal and stellate cells are found only in cultures of grossly normal intima, whereas elongated and asymmetric cells are found in practically all cultures. The ratio of elongated to asymmetric cells in cultures obtained from healthy aorta and atherosclerotic plaque is more or less the same at approximately 3:1. In cultures of fatty streaks the proportion of asymmetric cells exceeds 50%. Using immunofluorescence, all four types of cell were identified as smooth muscle cells. The possible reasons for the cellular polymorphism in primary culture and the prospects of utilizing this culture for the study of cellular aspects of atherosclerosis' pathogenesis are discussed.     

The role of aggregation in embryonal carcinoma cell differentiation

Cultures of the P19 line of embryonal carcinoma cells differentiate into various cell types including cardiac muscle when aggregated and exposed to medium containing 1% dimethylsulfoxide (DMSO). DMSO-treated aggregates became completely covered with an epithelial cell type 3 to 4 days following drug exposure. This epithelial cell was tentatively identified as primitive extraembryonic endoderm by its ultrastructural appearance and its possession of cytokeratin intermediate filaments. Muscle cells developed within the interior of DMSO-treated aggregates. They first became apparent 5 to 6 days after DMSO exposure and were characterized by the presence of striated muscle-specific myosin, immature myofibrils, and intercalated discs. We determined the proportion of cells developing into epithelium and muscle in aggregates of various sizes and showed that the proportion of epithelium was highest in small aggregates whereas muscle cells developed only in aggregates of relatively large size. The muscle was usually associated with necrotic areas which developed within the interior of large aggregates. Our results suggest that cardiac muscle differentiation in the aggregates requires both the DMSO-induced formation of an epithelial cell coat and one other condition which may be the proximity to necrotic areas.     

Stem cells, vascular smooth muscle cells and atherosclerosis

Stem cells have the ability to differentiate into a variety of cells to replace dead cells or to repair tissue. Recently, accumulating evidence indicates that mechanical forces, cytokines and other factors can influence stem cell differentiation into vascular smooth muscle cells (SMCs). In developmental process, SMCs originate from several sources, which show a great heterogenicity in different vessel walls. In adult vessels, SMCs display a less proliferative nature, but are altered in response to risk factors for atherosclerosis. Traditional view on SMC origins in atherosclerotic lesions is challenged by the recent findings that stem cells and smooth muscle progenitors contribute to the development of atherosclerotic lesions. Vascular progenitor cells circulating in human blood and the presence of adventitia in animals are recent discoveries, but the source of these cells is still unknown. The present review gives an update on the progress of stem cell and SMC research in atherosclerosis, and discusses possible mechanisms of stem/progenitor cell differentiation that contribute to the disease process.     

Ultrastructural morphometric study of efferent nerve terminals on murine bone marrow stromal cells, and the recognition of a novel anatomical unit: the "neuro-reticular complex"

In order to extend our understanding of the role of nerve fibers in the structure and function of bone marrow stroma, we have examined nerve terminals, arterioles, and capillaries in femoral bone marrow tissues of 50 C57BL strain mice, using electron microscopy and morphometric methods. Within the adventitia of arterioles, a particular type of cell, termed periarterial adventitial (PAA) cell, is characterized by a thin veil-like cytoplasm which concentrically surrounds both nerves and arterioles. Nerve fibers containing both unmyelinated and myelinated axons are distributed mainly between the layers of PAA cells, but are found rarely on the sinus walls or within the hematopoietic parenchyma. Quantitatively, the efferent nerve terminals with many synaptic vesicles are distributed mainly beside arterial smooth muscle cells (Type I: 58.8%) or between the layers of PAA cells (Type III: 33.2%), and rarely in hematopoietic parenchyma (Type II: 5.3%) or on sinus walls (Type IV: 2.7%). In the case of Type II-IV nerve terminals, efferent (autonomic) nerves and bone marrow stromal cells which are connected by gap junctions (sinus adventitial reticular cells, intersinusoidal reticular cells, and PAA cells) appear to constitute a potential functional unit for signal conduction. We would like to propose a new term for this anatomical unit in marrow, the "neuro-reticular complex."