Ultrastructure of the cumulus cell mass surrounding a human egg in the pronuclear stage

Summary The cumulus cell mass enclosing a penetrated human egg was studied. The egg, recovered from the Fallopian tube approximately 80 h after luteinizing hormone peak and 35 h after insemination, was surrounded by a large, expanded and dissociated cumulus. Dispersions of the outermost cumulus cell layers occurred during processing, the innermost cell layers remained attached enclosing the egg.The photomicrographs showed that the follicular cells were embedded in an intercellular matrix and contact via gap-junction-like structures between neighboring cells existed. Cumulus cell processes traversing the zona pellucida were not found. Two types of follicular cells coexisted within the cumulus, light and dark cells. These cellular types, were different in morphology and size. Light cells displayed cytoplasmic organelles normally associated with protein synthesis and steroidogenesis. Dark cells with long cytoplasmic processes were involved in sperm phagocytosis. It is suggested from the characteristics of the cytoplasmic organclles that dark cells seem to be modified light follicular cells.     

An electron microscopic study of sperm penetration into the rabbit egg after natural mating

The ultrastructure of fertilization has been studied in rabbit eggs recovered 11 to 15 hours after natural mating. Many sperm passing between the granulosa cells had undergone the acrosomal reaction, but this was not invariable, and, occasionally, intact sperm were present close to the zona pellucida. The cells of the corona radiata sometimes develop pseudopodial processes at the abovular surface and can ingest sperm after natural mating. The bulk of the content of the acrosome and the vesiculated elements formed during the acrosomal reaction, are lost before the sperm penetrates the zona pellucida, at which point the naked inner membrane of the acrosome is brought into intimate apposition with the zona. As the sperm cleaves a path through the zona pellucida, the posterior equatorial segment of the acrosome remains intact, and later persists as such in perivitelline sperm and quite possibly after incorporation of the sperm head into the vitellus. Sperm head entry into the vitellus is a two-fold process. The fertilizing sperm invariably fuses first with the vitelline membrane over the midposterior region of the head, whereas the rostral or acrosomal portion is drawn into the vitellus while encased by a flattened vesicle; this vesicle is comprised by the persistent inner membrane of the acrosome and externally by vitelline membrane sequestered from the egg surface. Soon after exposure to ooplasm, the sperm nucleus begins to decondense at a variable rate into a web of electron-dense strands; this process begins in the midposterior region, and then extends rostrally and caudally. At the same time the encasing membranes are reflected away from the anterior region of the nucleus, exposing subacrosomal material to the ooplasm. At this point the perforatorium remains, but this and the associated membranes are presumed to disintegrate eventually within the egg. After decondensation of the nucleus is complete, the faintly staining chromatin becomes enveloped by a series of compressed vesicles which together will form the porous limiting membrane of the male pronucleus. The last region to be incorporated is the sperm tail, the plasma membrane of which is lost as organelles of the tail pass into the ooplasm. During its incorporation, the midpiece engenders some reaction at the egg surface, and the mainpiece sometimes becomes fused with surface processes before it enters the body of the egg. The midpiece then commonly disintegrates, with dispersion of the mitochondrial sheath, whereas the mainpiece usually remains essentially intact until the time of syngamy or beyond.     

Changes in proteoglycans of ageing and osteoarthritic human articular cartilage: An electron microscopic study with polyethyleneimine

Background: Ageing and osteoarthritic (OA) cartilage show characteristic alterations in chondrocyte morphology and in the composition and content of matrix proteoglycans (PGs). Data concerning matrix components are mostly of biochemical nature. Ultrastructural histochemistry is needed to gain more information about distribution of these altered matrix components. Methods: We used the cationic dye polyethyleneimine (PEI) to visualize at the EM level alterations in the distribution and dimensions of PGs of human healthy young, healthy aged, and OA articular cartilage. Results: Young cartilage contained PEI-positive granules in the superficial layer and big winding PEI-positive structures in the deeper layers. In the healthy aged tissue, PEI-positive granules were observed throughout the matrix and smaller winding structures were present in the deeper layer. In OA cartilage both types of PEI-positive structures were absent in the superficial layer. Deeper in the matrix PEI-positive granules could be demonstrated. Moreover, PEI-positive angular structures were observed in the deeper zones. Conclusions: The differences in PEI-positive structures are a good reflection of the differences in PGs between young, ageing, and OA cartilage as demonstrated in biochemical studies. PEI, used at the EM level, gave more precise information concerning the localized changes in quality, quantity, and location of PGs in articular cartilage during ageing and disease. © 1994 Wiley-Liss, Inc.     

Effect of sperm-antibodies on acrosome reaction of human sperm used for the hamster egg penetration assay

The effect of anti-sperm antibodies (ASA) on the rate of acrosome reactions (AR) during "in vitro" capacitation of human sperm used for the hamster egg penetration assay (HEPA) was assessed. Motile sperm suspensions from donors were exposed to several sera and seminal plasma with sperm head-directed ASA, then they were washed and capacitated "in vitro." After capacitation, the proportion of acrosome-reacted viable sperm was assessed by staining with Fluoresceinated Pisum Sativum Agglutinin and supravital stain Hoechst 33258. ASA of any immunoglobulin class did not significantly affect either the AR rate, or the hamster egg penetration rate. In conclusion, interference of ASA on spontaneous AR rate during "in vitro" capacitation can not be advocated as an explanation of the impairment of the interaction of human sperm with egg or its vestments, which have been reported in several studies.     

Electron microscopic study of intrinsic cardiac ganglia in the adult human

The aim of the present study was to describe in detail the ultrastructure of intrinsic cardiac ganglionic cells in the healthy human as these cells appear to be directly involved in the development of tachycardia, atrioventricular block, ventricular fibrillation, and sudden cardiac death. Tissues examined in this study were obtained from hearts of 10 adult humans of either sex aged 22-80 years at autopsy performed no more than 8 h after death. The examined human intrinsic cardiac nerve cells were in most respects typical autonomic neurons surrounded by a sheath of satellite cells that was either uni- or multilayered. In addition to regular unmyelinated axons, prominent large axon terminals containing lamellated dense bodies, mitochondria and vesicles in the cytoplasm were observed in the ganglion neuropil. Synaptic profiles were more common in the ganglion neuropil than on neuronal somata. According to axon terminal contents, synaptic profiles were of three types. The most common Type 1 synaptic profiles contained a predominance of small clear, with a few larger dense-cored vesicles and mitochondria. Type 2 synaptic profiles, in addition to the same components as in Type 1, had glycogen-like particles. Type 3 vesicle-containing profiles clearly differed from both the previous ones as they were the largest in diameter and included plentifiul large clear pleomorphic or dense-cored vesicles together with small clear and larger dense-cored vesicles, mitochondria, dense and multivesicular bodies. Independently of age of the human, the most frequent neuronal abnormality was an abundant accumulation of inclusions inside of somata and dendrites that, in profile, appeared like circular membranous or fine granular bodies variable in electron density. In addition to inclusions, some neuronal somata and dendrites had strongly swollen mitochondria filled up with granular material in spite of their close association with normal looking ganglionic neurons. Structures resembling an axon growth cone in profile were revealed inside of cardiac ganglia derived from an 80 year old man. In conclusion, the present results provide baseline information on the normal ultrastructure of intracardiac ganglia in healthy humans which may be useful for assessing and interpreting the degree of damage of ganglionic cells both in autonomic and sensory neuropathies of the human heart.     

人类睾丸精子和附睾精子的顶体蛋白酶活性

目的：探讨人类睾丸精子和附睾精子的顶体蛋白酶活性。方法：应用明胶薄层试验、穿卵试验和透射电镜观察顶体蛋白酶活性及其影响。结果：未经洗涤的睾丸精子和附睾精子不出现明显的晕轮，洗涤后则显示出顶体蛋白酶活性。附睾精子组的平均晕轮直径显著高于睾丸精子组（Ｐ＜００１）。附睾精子能与去透明带地鼠卵受精。老化和畸形的附睾精子降低或丢失酶活性。结论：睾丸精子已初步发育具功能活性的顶体蛋白酶，进入附睾顶体蛋白酶逐渐发育至功能成熟，而曲细精管和附睾管内液体存在着抑制酶活性的物质     

Scanning electron microscopic study of the adhesion of a human megakaryocytic leukemia cell line (CMK11-5)

To characterize the CMK11-5 subclone of a human megakaryocytic leukemia cell line (CMK), an ultrastructural study on adhesion was performed. The CMK11-5 cells showed irreversible attachment to rabbit aortic subendothelium accompanied by several morphological changes such as flattening and the spreading out of pseudopodia. These morphological changes are similar to those observed in normal platelets during attachment. The attachment of CMK11-5 cells to rabbit aortic subendothelium indicates that human megakaryocytes may possess an adhesion function like that of platelets. The CMK cell line and its CMK11-5 subclone with megakaryocytic properties appear to be useful for studying the function of megakaryocytes.     

Lipofuscin in the cerebellar cortex of albino rats: An electron microscopic study

Summary The ultrastructure of autofluorescent, PAS-positive lipofuscin in Purkinje, granule, Golgi epithelial, basket and stellate, microglial and perivascular cells in the cerebellar cortex of senescent rats is described. The membrane-bounded pigment is composed of three elements: 1) electron-lucent homogeneous droplets, 2) a granular matrix and 3) intensely osmiophilic patches. The proportions of these three components vary between cell types and one can grossly differentiate a neuronal and a glial lipofuscin. The lipofuscin granules of stellate and perivscular cells are different from lipofuscin of other cerebellar neurons and glia. It can be concluded from these morphological observations that each cerebellar cell type has its distinct lipofuscin.Supported by the Deutsche Forschungsgemeinschaft La 184/5I would like to thank Mrs. v. Bronewski and Mr. H. Boffin for their technical assistance     

Ultrastructure of a two-cell human embryo

Summary A two-cell human embryo recovered from the Fallopian tube 82 h following the LH peak in plasma and 37 h after a single episode of intercourse was examined by transmission electron microscopy. At the time of recovery the embryo was denuded of cumulus cells, and both the zona pellucida and the two adjoining blastomeres were intact. The finding of two polar bodies in the perivitelline space, two nucleated blastomeres and remnants of the fertilizing sperm tail within the cytoplasm of one of them, were considered as evidences that the embryo was normally fertilized. Among the most compicuous features found were the presence of very distinct desmosome-like structure between blastomeres, and the cytoplasmic cell organelles distribution in three areas referred as: a sub-cortical, a middle and a perinuclear bands. An outstanding feature was the extensive blebbing of the nuclear envelope. In general, the features seem to correspond to a normally developing two-cell embryo undergoing cleavage at a normal rate.     

An electron microscopic study of astroglia and oligodendroglia in the lateral geniculate nucleus of aged rats

The ultrastructural features of glial cells in the lateral geniculate nucleus of aged rats have been studied. Abundant filaments as well as heterogeneous dense bodies are observed in the majority of astrocytes. They frequently surround both axons and nerve terminals showing signs of degeneration. In addition, some degenerating myelinated axons are seen in phase suggestive of engulfment by astrocyte processes. Oligodendrocytes display broad processes containing an organelle-rich cytoplasm and a continuity between their plasma membrane and the outer myelin lamellae which partially ensheath the adjacent axons. Multivesicular bodies and pleomorphic dense inclusions, composed of amorphous material as well as laminated structures, are also present in oligodendrocytes. The significance of these morphological features is discussed in relation to process of normal ageing.     

Quantitative electron microscopic analysis of the penetration of VSV into L cells

Vesicular stomatitis virus (VSV) has been reported to penetrate L cells both by viropexis and by fusing with the cellular plasma membrane. The procedures used to produce these apparently contradictory results were significantly different. Quantitative electron microscopic methods were used to analyze the effect of these different procedures and the presence or absence of serum on the adsorption and penetration of VSV into L-929 cells. When penetration was analyzed following adsorption in the cold, VSV entered cells almost exclusively by viropexis. There was a quantitative relationship between the disappearance of extracellular attached virus and the appearance of virus in invaginations, and, somewhat later, in small intracellular vacuoles. Fusion was only rarely observed. When the multiplicity was lowered to 10–15 particles per cell, the same findings were obtained. When adsorption was achieved by centrifuging virus-cell mixtures at 18,000 g for 15 min, viropexis was again the predominant mode of penetration, but fusion occurred at a significant level, indicating that centrifugation per se played a role in the incidence of fusion. In all cases, serum reduced the amount of virus adsorbed, but did not affect the mode of penetration.     

A freeze-fracture electron microscopic study of tight junctions of epithelial cells in the human uterus

Summary Freeze-fracture electron microscopy has been used to study tight junctions of luminal epithelial cells of the human uterus. The junctions are deeper and more extensive in the middle of the menstrual cycle than they are later in the cycle. The results suggest that the contents of the uterine lumen may be more closely regulated at some times than at others.     

The ciliary ganglion of the cat: a light and electron microscopic study

The ciliary ganglia of eight healthy adult cats were studied by light and electron microscopy. The ganglion, measuring about 2 mm in length, was consistently found to be attached to the branch from the oculomotor nerve supplying the inferior oblique muscle. The number of neurons varied from 2773 to 3794 after applying Abercrombie's correction. The mean of average somal diameter of the neurons was 36.5 m (SD = 5.0 m) and the mean of somal cross-sectional area was 904.2 m² (SD = 262.8 m²). The mean of average nuclear diameter was 13.9 urn (SD = 1.8 m) and the mean of nuclear cross-sectional area was 142.2 m² (SD = 37.1 m²). The mean of the aspect ratios of the soma and nucleus were 1.2 (SD = 0.1) and 1.1 (SD = 0.1) respectively. The frequency distributions of these parameters were all unimodal. Under the light microscope, the Nissl granules in the neurons were prominent and were distributed peripherally, perinuclearly or randomly in the cytoplasm. Under the electron microscope, the rough endoplasmic reticulum showed a similar pattern of distribution in the cytoplasm. In some neurons, glycogen-like granules were present; these were either distributed randomly throughout the cell, or aligned in single rows in relation to sub-surface cisterns and between the cisterns of smooth and rough endoplasmic reticulum. Most of the dendrites were short protrusions from the cell body; some contained glycogen-like granules. Occasionally, the dendritic protrusions were electron-dense. All the synapses encountered were axodendritic. In most axon terminals, the synaptic vesicles were spherical and measured 30–50 nm in diameter; in some, they were flattened, measuring 50 nm by 20 nm. Some axon terminals containing either spherical or flattened synaptic vesicles also contained large dense-cored vesicles that measured 80–100 nm, while their dense core measured 40–60 nm.     

An electron microscopic study of plasmatic arterionecrosis in the human cerebral arteries

Summary An electron microscopic study of the intracerebral arteries from 9 hypertensive cases was performed in order to elucidate the morphogenesis of the plasmatic arterionecrosis which was considered to be the direct cause of hypertensive intracerebral hemorrhage. In the preceding stage of the arterial lesions, marked necrosis of medial smooth muscle cells and increase of basement membrane-like substance in the intima and media were observed. The lumina of these arteries were slightly dilated. The dilatation and hemodynamic factors were supposed to cause endothelial injury resulting in blood plasma insudation into the intima through the opened spaces between endothelial cells. The insudated blood plasma dispersed and dissolved the basement membrane-like substance, collagen and elastic fibers in the arterial wall, leading to the development of the plasmatic arterionecrosis.This study was supported by a Grant-in-Aid for Scientific Research of the Japanese Ministry of Education (No. 857052).     

An electron microscopic investigation into the possible source of new muscle fibres in teleost fish

This study is based on transmission electron microscopic (TEM) investigations of deep (fast, white) teleost fish muscle proliferation in early developmental stages of three European cyprinid species and the rainbow trout. Our fine structural findings provide evidence that early myotomal growth in these animals may utilize different mechanisms that are activated in close succession during early life history. First, initial enlargement of the deep muscle bulk in the embryo seems to be due to hypertrophy of the somite-cell derived stock of muscle fibres. Second, we suggest that deep muscle growth becomes additionally powered by attachment of presumptive myogenic cells that originate from and proliferate within the adjacent mesenchymal tissue lining. Third, mesenchyme-derived muscle cell precursors are thought to enter the myotomes via the myosepta. After migration between the pre-established muscle fibres these cells may function as myosatellite cells, thus at least partly providing the stem cell population for subsequent rapid hyperplastic growth. Finally, there is evidence that presumptive deep muscle satellite cells also proliferate by mitotic division in situ. A similar process of myogenic cell migration and proliferation may foster intermediate fibre differentiation. The model of myogenic cell migration is discussed in view of in vitro and in vivo data on satellite cell migratory power and with respect to temperature-induced and species dependent differences. As for the latter, our results indicate that patterns of muscle differentiation may diverge between a fast growing salmonid species and a moderately growing cyprinid species of similar final size. The model is compatible with the wellestablished idea that teleost muscle growth may rely on different subclasses of myosatellite cells.     

Muscle spindles in immobilized muscle: electron microscopic study of recovery

This study is concerned with the morphological recovery process of muscle spindles following a long period of immobilization. The right hindlimbs of rats were fixed with a plaster cast for 4 weeks. Thereafter, four groups of rats were examined by electron microscopy. One group served as the control after the cast was removed. The other three groups were examined after free walking for 4, 8, and 12 weeks, respectively. The muscle spindles (tibialis anterior muscle) of the individual animals were then ultrastructurally analyzed. The morphological alterations (of the outer capsule, intrafusal muscle fibers, and intrafusal nerve components) gradually recovered during free walking and regained almost all normal features in 12 weeks after returning to walking.A part of this research was presented at the 25th Annual Meeting of the Clinical Electron Microscopy Society of Japan, Matsumoto, September 28–30, 1993.     

An electron microscopic study of intestinal metaplasia in human gallbladder.

Areas of intestinal metaplastic epithelium in gallbladders removed by cholecystectomies performed for gallstones were studied with the electron microscope. Three gallbladders contained areas of goblet cells and endocrine enterochromaffin-like cells and one gallbladder also Paneth cells. The goblet cells contained mucin granules of slightly variable size and shape and relatively great electron lucency. The intervening columnar epithelial cells contained various amounts of electron-lucent mucin granules. The round or oval enterochromaffin-like cells rested on the basement membrane, and in these cells the small, round, electron-opaque secretory granules were located in the infranuclear region. The supranuclear cytoplasm of the Paneth cells in the intestinalized epithelium contained typical large, round secretory granules. The fine structures of the various cells in the metaplastic epithelium bore resemblance to those of the cells in the intestinalized stomach mucosa.     

Apocrine carcinoma of the breast containing foam cells. An electron microscopic and immunohistological study

The detailed light and electron microscopic and immunohistological features of an invasive apocrine carcinoma of the breast developing in a 78-year-old woman are presented. The stroma of the tumour contained non-neoplastic lipid-filled (foam) cells. To our knowledge, these cells have not been described before in invasive breast carcinoma. Their electron microscopic and immunohistological features confirm their histiocytic nature.