The ultrastructure of the sinuatrial ring bundle and of the caudal extension of the sinus node in the right atrium of the rabbit heart

Summary The cells of the sinuatrial ring bundle are smaller than the ordinary myocardial cells; they have a regular outline and a large content of myofibrils exhibiting distinct H-bands and M-lines. Rudimentary T-tubules are found. The cells are connected by frequent nexus junctions, desmosomes and regions of interfibrillar contact, both on the well developed intercalated discs and at the periphery of the cells.The cells in the cauda of the sinus node, which extends alongside the crista terminalis together with the right branch of the sinuatrial ring bundle, are irregularly outlined and have a highly variable diameter (1–10 m). They occur in clusters of closely packed cells. The content of myofibrils is sparse and the fibrils exhibit no M-lines and only weak H-bands. No T-tubules are found. The cells are not connected by intercalated discs and no nexus junctions are found.Both tissues contain unmyelinated nerves and nerve fibres. Varicosities with mitochondria and vesicles are found in close apposition to the muscle cells.     

Ultrastructure of the respiratory epithelium in the lungs of the tortoise,Testudo graeca

The respiratory epithelium in the lungs of the tortoise (Testudo graeca) has been studied by electron microscopy. The epithelium consists of a mosaic of two different cell types (here called "pneumonocytes"). Type I pneumonocytes are roughly squamous and possess attenuated flanges of cytoplasm which extend over the septal capillaries. Localized cytoplasmic expansions are often present near the periphery of these flanges. Most of the organelles are concentrated in the perinuclear region; the most prominent of these are the mitochondria and osmiophilic inclusions. In contrast, type II pneumonocytes are cuboidal and are richly endowed with organelles including large Golgi complexes, extensive endoplasmic reticulum and numerous inclusion bodies. The morphological evidence suggests that type I pneumonocytes are involved in the secretion of osmiophilic material (presumed to be pulmonary surfactant) and in maintaining the integrity of the air-blood barrier. Type II pneumonocytes appear to be concerned solely with the production of surfactant.     

Study on the morphology of the gall-bladder of the goat

200 gall-bladders of goat were studied for histology and histochemistry. The lining epithelium is tall columnar with striated border. The glands are mucous and serous, and the secretion of both surface and glands is a polyssaccharide-protein complex. The regional differences at neck, body and fundus of the gall-bladder are described. Few enterochromaffin cells with granules, which are PAS-positive and contain 5-hydroxytryptamine, are encountered at the wedge between the granular epithelial cells and the cells lining the crypts. The relationship between these cells and lymphocytic infiltration is discussed. The thick circular muscle layer at the neck region is considered a sphincter of the gall-bladder.     

Corticotrophic cells in the rostral zone of the pars intermedia and in the adjacent neurohypophysis of the rat and mouse

Summary In the mouse, the rostral zone of the pars intermedia is almost exclusively composed of typical corticotrophic cells. They are located around and even within the neural stalk, at the level of transition between stalk and neural lobe. In the rat, the corticotrophic cells of the rostral zone are found in scattered islets among the MSH producing cells, and also in the neural lobe. In both the rat and mouse, these cells are in direct contact with various types of nerve terminals. Synaptoid contacts with aminergic and neurosecretory nerve fibers are observed. Furthermore they are also closely related to the hypophysial portal vessels. Following adrenalectomy, the cells located in the neurohypophysis always react more intensely than tose in the rostral zone. The functional significance of these corticotrophic cells which are subject to both humoral and neural regulation remains as yet hypothetical. Their participation in neurogenic stress response seems probable.     

The variances of the distributions of the combinations of the sexes within mammalian litters: Notes to mark the centenary of the problem

It is 100 years since Gini noted that in some samples of litters of mice and rabbits, the variances of the distributions of the combinations of the sexes are sub-binomial. In other words, in contrast with binomial expectation, there are too many litters in which the sexes are equally balanced, and there are too few unisexual litters. In the intervening years, this finding has been replicated in a number of further species, but no explanation has become established. Potential explanations are reviewed here, and it is suggested that the most likely cause is that, at the time of formation of the zygotes, p, the probability that a zygote will be male, varies from one zygote to another within litters, thus constituting an example of Poisson variation. And it is a standard result in probability theory that such variation causes sub-binomial variance.     

On the path to understanding the nature of cancer

In this essay crucial problems of the origin of cancer and the development of malignancy are discussed. The problem of precancer and three ways leading to malignancy are considered: induction of tumor precursors, accumulation of genetic traits common for tumor growth, and the role of inflammation in tumor induction. The nature of viral oncogenes and modes of their action are described in the context of their origin as a component of the viral genome. Oncogenes of RNA-containing viruses and DNA-containing tumorigenic viruses are described together with cellular protooncogenes, which are progenitors of RNA-containing viral oncogenes. Hematological malignancies are described as an intermediate form between simple tumors induced by a single oncogene and more complicated epithelial tumors. The roles of tumor suppressor genes and the interaction of several oncogenes in the formation of carcinomas and also the role of progression in tumor evolution are discussed.     

About the morphological relationships of the sarcoplasmic reticulum in the sole plate area of the frog

In the present investigation the sole plate area of motor end plates of the frog is ultrastructurally examined with different postfixation methods. We concentrated in this case on the proof of the smooth and rough sarcoplasmic reticulum of the sole plate. The relations of the smooth and rough sarcoplasmic reticulum to subsynaptic folds and the local T-system and its connections to diads and triads in the sole plate area are represented. The morphological differences between mammal and frog are pointed out. The possible functions of the sarcoplasmic reticulum in the myofibril-free sarcoplasm are discussed.     

Connections between the posterolateral nucleus of the thalamus and the parietal and occipital areas of the cerebral hemispheres in the cat

A light optic and electron microscopic investigation on distribution of fibers from the thalamic posterolateral nucleus has been performed in the cat cerebral cortex. The fibers studied are revealed in the fields 7, 19 and 18. In the field 7 they are most numerous, comparatively seldom they are found in the field 19 and still more seldom--in the field 18. In the fields 7 and 19 identical peculiarities on distribution and termination of the fibers are noted: they spread across the whole cortex and end in all the layers with a predominant concentration in the layers III and IV. Most of the fibers make contacts on small dendritic branches and spines. In the field 18 the fibers are mainly limited by the medial layers and terminate predominantly on small, middle-sized dendritic branches, and comparatively rare--on the spines.     

From the light to the darkness: thriving at the light extremes in the oceans

Light-acclimation processes are central to allowing photosynthesis in aquatic ecosystems to span from high light conditions, that are 10-fold higher than the light levels required to saturate photosynthesis, to the deep sea with extremely low light levels. In dim light systems, nutrient levels are often high, and cells maximize the absorption of light by increasing the cellular pool of pigments. The upper limits of light absorption are constrained by the package effect, which ultimately restricts the benefit of the light absorption associated with an increase in cellular pigmentation, thus decreasing the cost/benefit ratio relative to the metabolic cost of manufacturing cellular light-harvesting pigments. At extremely low light levels in the deep sea, chloroplasts are sequestered in numerous organisms; however, these species are not obligate autotrophs and supplement a heterotrophic/mixotrophic existence with opportunistic autotrophy. While low light acclimation is based on maximizing light absorption, photosynthetic systems under high light, in addition to decreased light-harvesting cross sections, rely on energy-dissipation processes to avoid light-induced damage to the photosynthetic apparatus and other free radical susceptible cell structures. Dissipation of excess light energy represents the largest sink of the absorbed light in high light environments; however, these processes remain largely unstudied and are rarely quantified. Cells supplement their energy-dissipation processes through increasing the capacity to remove high-light-generated radicals and/or inducing vertical movement. Improved understanding of strategies remains central for the understanding of algal distributions in nature and has broad industrial implications.     

Demonstration of the heterogeneity of the mast cell population on the basis of the mucopolysaccharide content.

From the aspect of its mucopolysaccharide content the mast cell population is not homogeneous. The pulmonary and heart muscle mast cells of the rat are alcian blue positive, the mast cells of the thyroid gland, lymph nodes, subcutaneous connective tissue, mesentery and peripheral nerve are safranin positive, whereas among the mast cells of the peritoneal cavity and the thymus there are both alcian blue and saffranin positive forms. The least acid mucopolysaccharides are in the mast cells of the peritoneal fluid, the mesentery and the lungs, whereas the most acid ones are in the mast cells of the lymph nodes, the subcutaneous connective tissue and the thyroid gland. There is a considerable difference between the two last mentioned organs. The mast cells of the subcutaneous connective tissue are end-product cells without amine or precursor turnover, whereas the mast cells of the thyroid gland incorporate and deliver amines, which may participate in the regulation of the host gland.     

Changes in the ultrastructure of the gills of the river lamprey,Lampetra fluviatilis (L.), during the anadromous spawning migration

Summary Two types of mitochondria-rich cells were found in the interplatelet areas of the gills of the migrating river lamprey. Both cell types are thought to be responsible for ion-transport across the gills. In the fresh-run migrant the gills are dominated by large, flask-shaped cells which show some ultra-structural similarities with the teleost chloride cell and have been tentatively referred to as ion-excretory cells. During the spawning migration the ion-excretory cells are replaced by smaller, mitochondria-rich cells which are similar in structure to the presumed ion-transporting cells in the ammocoete gill. They lack the tubular, smooth-membraned endoplasmic reticulum so characteristic of the lamprey ion-excretory cell and the teleost chloride cell and have been referred to as ion-uptake cells. The ion-uptake cells are found during the stenohaline, freshwater phases of the lamprey's life history. Ion-excretory cells are present during the periods of the life cycle when the animal is euryhaline. The possibility that the ion-excretory cells are also responsible for ion-uptake in fresh water is discussed.     

On the translocation of proteins across the chloroplast envelope

Most of the chloroplast proteins are coded for in the nucleus and are synthesized in the cytosol from where they are subsequently transported into the different chloroplast compartments. The structural properties of the N-terminal extensions (transit peptides) of these nuclear-coded precursor proteins are discussed as well as the energy requirements for their translocation and the involvement of receptor proteins and that of other (ATP-dependent) factors.     

Ultrastructural studies on the hypothalamic neurosecretory neurons of the rat

Summary The general ultrastructural features of the hypothalamo-neurohypophysial system in rats with hereditary hypothalamic diabetes insipidus (DI-rats, Brattleboro strain) are described. There is no decisively distinguishing difference between the neurons of the supraoptic and paraventricular nuclei. The neurons of both nuclei show signs of active protein synthesis. The perikarya of the neurons are markedly hypertrophic, the nuclei are large and the nucleoli prominent. In the cytoplasm there are numerous ribosomes, abundant rough-surfaced endoplasmic reticulum and extensive Golgi complexes. However, very few neurosecretory granules are to be seen. The axons of the hypothalamo-neurohypophysial tract are likewise enlarged and the paucity of neurosecretory granules is a striking feature also in the area of the tract. The majority of nerve endings in the posterior pituitary of DI-rats are devoid of neurosecretory granules. Microvesicles are abundant in the nerve endings and there are findings which suggest that microvesicles are involved either in endoor exocytosis. The signs of active protein synthesis and the concomitant paucity of neurosecretory granules are interpreted to imply transportation of the secretory proteins in an extragranular phase. The possible mode of release of the secretory proteins from the nerve endings and the role of microvesicles therein are discussed.This study has been supported by grants from the Finnish Cultural Foundation and the Sigrid Jusélius Foundation. The collaboration of Professors Antti Arstila and Tapani Vanha-Perttula is gratefully acknowledged.The Brattleboro-rats were kindly provided by Dr. Heinz Valtin, to whom we express our thanks.     

北京地区蕨类植物区系分析

对北京地区蕨类植物区系进行了初步分析,研究表明,北京共有蕨类植物77种,隶属于19科34属,以蹄盖蕨科、岩蕨科、鳞毛蕨科、卷柏科等为优势科,以岩蕨属、卷柏属、铁角蕨属等为优势属,科内及属内分化程度较低,种类组成贫乏;地理成分以温带成分占优势,有11属为温带分布属,占非世界分布属总数的61．11％,除世界种和中国特有种外,全为温带性质的种;生境特点以石生为主,大多数种类分布在北京西部和北部的山区;与河北的关系最为密切,其次为山西、内蒙、辽宁、山东,与秦岭也有一定的联系,与西藏的关系疏远。     

Biomathematics in Embryogenesis and the Conception of the Phoronomics of the Entropy

The fundamental ideas of the phoronomics of the entropy are developed. There are some important kinematic quantities and three kinematic decompositiones.     

Ultrastructure of the stria vascularis of the auricular labyrinth of the rabbit]

In the composition of the stria vascularis of the rabbit cochlea there are three types of cells: edging, medial and basal cells. The structure of these cells, their disposition and interrelationships within the stria vascularis are described. The nodes of the basal membrane whose ramification covers long mitichondria concentrating at the basement of edging cells are found in the structure of capillaries of the cochlea stria vascularis. It may be supposed that this powerful mitochondrial apparatus refers to the capillary system of the stria vascularis and represents a hypertrophic mitochondrial apparatus of pericytes. The capillaries of the stria vascularis are distributed mainly in longitudinal direction while the capillaries disposed transversely which are likely to be anastomoses were also found.     

On the ontogeny of the haptor and the evolution of the Monogenea

Data on the ontogeny of the posterior haptor of monogeneans were obtained from more than 150 publications and summarised. These data were plotted into diagrams showing evolutionary capacity levels based on the theory of a progressive evolution of marginal hooks, anchors and other attachment components of the posterior haptor in the Monogenea (Malmberg, 1986). 5 + 5 unhinged marginal hooks are assumed to be the most primitive monogenean haptoral condition. Thus the diagrams were founded on a 5 + 5 unhinged marginal hook evolutionary capacity level, and the evolutionary capacity levels of anchors and other haptoral attachement components were arranged according to haptoral ontogenetical sequences. In the final plotting diagram data on hosts, type of spermatozoa, oncomiracidial ciliation, sensilla pattern and protonephridial systems were also included. In this way a number of correlations were revealed. Thus, for example, the number of 5 + 5 marginal hooks correlates with the most primitive monogenean type of spermatozoon and with few sensillae, many ciliated cells and a simple protonephridial system in the oncomiracidium. On the basis of the reviewed data it is concluded that the ancient monogeneans with 5 + 5 unhinged marginal hooks were divided into two main lines, one retaining unhinged marginal hooks and the other evolving hinged marginal hooks. Both main lines have recent representatives at different marginal hook evolutionary capacity levels, i.e. monogeneans retaining a haptor with only marginal hooks. For the main line with hinged marginal hooks the name Articulon-choinea n. subclass is proposed. Members with 8 + 8 hinged marginal hooks only are here called Proanchorea n. superord. Monogeneans with unhinged marginal hooks only are here called Ananchorea n. superord. and three new families are erected for its recent members: Anonchohapteridae n. fam., Acolpentronidae n. fam. and Anacanthoridae n. fam. (with 7 + 7, 8 + 8 and 9 + 9 unhinged marginal hooks, respectively). Except for the families of Articulonchoinea (e.g. Acanthocotylidae, Gyrodactylidae, Tetraonchoididae) Bychowsky's (1957) division of the Monogenea into the Oligonchoinea and Polyonchoinea fits the proposed scheme, i.e. monogeneans with unhinged marginal hooks form one old group, the Oligonchoinea, which have 5 + 5 unhinged marginal hooks, and the other group form the Polyonchoinea, which (with the exception of the Hexabothriidae) has a greater number (7 + 7, 8 + 8 or 9 + 9) of unhinged marginal hooks. It is proposed that both these names, Oligonchoinea (sensu mihi) and Polyonchoinea (sensu mihi), will be retained on one side and Articulonchoinea placed on the other side, which reflects the early monogenean evolution. Except for the members of Ananchorea [Polyonchoinea], all members of the Oligonchoinea and Polyonchoinea have anchors, which imply that they are further evolved, i.e. have passed the 5 + 5 marginal hook evolutionary capacity level (Malmberg, 1986). There are two main types of anchors in the Monogenea: haptoral anchors, with anlages appearing in the haptor, and peduncular anchors, with anlages in the peduncle. There are two types of haptoral anchors: peripheral haptoral anchors, ontogenetically the oldest, and central haptoral anchors. Peduncular anchors, in turn, are ontogenetically younger than peripheral haptoral anchors. There may be two pairs of peduncular anchors: medial peduncular anchors, ontogentically the oldest, and lateral peduncular anchors. Only peduncular (not haptoral) anchors have anchor bars. Monogeneans with haptoral anchors are here called Mediohaptanchorea n. superord. and Laterohaptanchorea n. superord. or haptanchoreans. All oligonchoineans and the oldest polyonchoineans are haptanchoreans. Certain members of Calceostomatidae [Polyonchoinea] are the only monogeneans with both (peripheral) haptoral and peduncular anchors (one pair). These monogeneans are here called Mixanchorea n. superord. Polyonchoineans with peduncular anchors and unhinged marginal hooks are here called the Pedunculanchorea n. superord. The most primitive pedunculanchoreans have only one pair of peduncular anchors with an anchor bar, while the most advanced have both medial and lateral peduncular anchors; each pair having an anchor bar. Certain families of the Articulonchoinea, the Anchorea n. superord., also have peduncular anchors (parallel evolution): only one family, the Sundanonchidae n. fam., has both medial and lateral peduncular anchors, each anchor pair with an anchor bar. Evolutionary lines from different monogenean evolutionary capacity levels are discussed and a new system of classification for the Monogenea is proposed.In agreeing to publish this article, I recognise that its contents are controversial and contrary to generally accepted views on monogenean systematics and evolution. I have anticipated a reaction to the article by inviting senior workers in the field to comment upon it: their views will be reported in a future issue of this journal. EditorIn agreeing to publish this article, I recognise that its contents are controversial and contrary to generally accepted views on monogenean systematics and evolution. I have anticipated a reaction to the article by inviting senior workers in the field to comment upon it: their views will be reported in a future issue of this journal. Editor     

林跳鼠亚科的系统学研究述评

林跳鼠亚科分布在亚洲和北美洲,虽然种类及数量都不多,但对该亚科的分类和系统发育关系一直存在争议,近几年对林跳鼠哑科分子系统学的研究,产生了一些与形态学、生物地理学等研究不同的结果.本文对林跳鼠亚科系统学研究的一些工作加以述评,归纳出林跳鼠亚科在系统学方面还存在的问题,并对林跳鼠亚科系统学的进一步研究提出了一些建议.     

生物医药关键技术发展趋势

近年来,生物医药研究人员正在药物的设计、发现、试验、制备,以及检测技术、其他诸如纳米、信息、光学等高技术的融合应用方面致力于更新观念的研究开发,并已取得众多突破,在相关领域形成新的技术趋势。在药物设计方面,随着遗传信息方面的研究进展越来越快,核酸为靶的药物设计已成为新的热点;在疫苗方面,基因疫苗的研制已成为新方向,其技术应用趋向可调控、更安全、更高效生产等,科研人员同时还致力于解决基因疫苗的安全性;在治疗方面,抗体工程和组织工程分别成为药物治疗和组织器官再造的热点;新型药物输送技术正成为业界追逐的目标,药物传输公司正在开发多技术平台,提高药物的效能,减少不良反应和降低成本;药物安全问题已在全球范围内达成共识,美、英、日、欧盟等国均在积极开展药物安全性方面的研究,开发药物安全监测系统;疾病诊断与检测的新技术表现为更高效、准确、快速、早期的趋势,科研人员同时还致力于降低诊断检测产品的价格,以使更多人受益;IT技术、光电技术、纳米技术等新技术正被积极应用于生物医药领域,为大型制药公司和生物技术公司提供药物发现、设计、毒性研究等更新途径的新技术系统。