Light and electron microscopic studies of postcapillary venules in developing human fetal lymph nodes

Developing lymph nodes from 30 human fetuses with crownrump lengths (CRL) of 38 mm (8.7 wk) to 245 mm (26 wk) were studied by light and electron microscopy. Blood vessels that appear to be postcapillary venules (PCV) are present in nodes of 47 mm CRL and older fetuses. These venules first appear in nodes when the nodal population of lymphocytes is sparse. In these early nodes PCV are distributed randomly and consist of a low endothelium, underlying basal lamina and incomplete pericyte sheath. Early nodal PCV are distinguished from other nodal blood vessels by the presence of lymphocyte diapedesis and several luminal lymphocytes. In the late stages of nodal development PCV are the more common noncapillary blood vessel and appear in the parenchyma near the periphery of the node. Late nodal PCV are generally characterized by a cuboidal endothelium that is rich in Golgi apparatus, lysosomes and Weibel-Palade bodies. The lumen and wall of late nodal PCV contain lymphocytes. The relationship between the development of the parenchyma of fetal nodes and the appearance and activity of PCV, the passage of lymphocytes through the PCV wall and the fine structure of developing PCV are described. It is suggested that the lymphocytes that first appear in developing nodes, and the majority of the lymphocytes found in late nodes, migrate to the node via the blood vascular system and enter the nodal parenchyma by passing across PCV endothelium.     

超声引导脐静脉穿刺术在孕中晚期产前诊断中的应用价值

目的探讨超声引导脐静脉穿刺术在孕中晚期产前诊断中的安全性及应用价值。方法对875例孕周为18~33+4的孕中晚期孕妇因各种原因行超声引导脐静脉穿刺术,并对所抽取的脐静脉血进行核型分析。结果超声引导脐静脉穿刺成功率为99.5%;胎盘或脐带一过性渗血发生率22.5%;胎儿短暂心动过缓发生率4.0%;胎儿丢失发生率0.5%。染色体核型分析发现核型异常65例,异常率为7.4%,其中数目异常41例;结构异常24例。另发现重型地中海贫血8例,巨细胞病毒感染2例。异常诊断结果总检出率为8.6%。结论超声引导下脐静脉穿刺术具有很高的成功率和安全性,弥补了孕中晚期产前诊断方法的空缺,并能从多方面进行病因学诊断。     

Endocrine-like cells in human fetal lungs: An electron microscopic study

This study of primitive bronchial epithelium in human fetuses revealed cells of distinctive ultrastructural appearance. These cells contained cytoplasmic granules similar to neurosecretory-type granules and are termed fetal Kultschitzky-type cells (K-type cells) of lung. The fetal K-type cells appear similar to certain cells in mature lungs and in other tissues that have an endocrine function. The advanced cytoplasmic differentiation and large numbers of K-type cells in early stages of fetal development suggests that these cells might also have an important, probably endocrine function.     

Extracellular space in the developing retina assessed by electron microscopy: laminar and topographic distribution

The extent of extracellular space (ECS) in the developing retina of the cat has been measured by electron microscopy in material fixed using techniques developed by others to preserve ECS. ECS is generally greater in foetal than in adult material. It is particularly marked in the plexiform layers of retina at the time of synaptogenesis and in the axon layer at the time of axon growth. The changes in ECS occur first in the central retina, and spread to the periphery. These observations suggest that the high volumes of ECS found in the foetus are not artefactual, but accompany and may play a role in developmental processes.     

Histological and electron microscopic milestones in the development of the retina of a marsupial wallaby, Macropus eugenii

Summary Retinal differentiation in the pouch young of the wallaby Macropus eugenii was characterized microscopically and morphometrically. Mitosis occurs until early in the second month in the central retina, and until early in the fourth month, peripherally. Separation of the neuroblast layer by the outer plexiform layer did not immediately halt cell division. The retinal surface continued to expand well past the time of cessation of proliferation. Cell death in the ganglion cell layer continued through the fourth month centrally and to nearly five months in the periphery. The major period of cell death was coincident with the segregation of retinal afferents and the refinement of topography in the superior colliculus and dorsal lateral geniculate necleus. Beginning in the third month retinal thickness, measured between the outer limiting membrane and nerve fiber layer declined equally in peripheral and central regions. At all stages the combined thicknesses of the outer and inner nuclear layer in the retinal periphery was greater than that in the center. Together with a late thickening of the inner plexiform layer, the data are consistent with the suggestion that expansion of peripheral non-ganglion cell elements may play a role in development of center to periphery differences in ganglion cell distributions.Retinal differentiation of the wallaby follows the pattern of most mammals. The onset of development of key milestones for the acquisition of retinal function occurred in the sequence: conventional synapse formation prior to ribbon synapse formation in the inner plexiform layer, and photoreceptor outer segment differentiation prior to terminal triad synapse formation.     

Herpes simplex viral infection in human neonates: an immunohistochemical and electron microscopic study

Specimens obtained at autopsy from six neonates with herpes simplex virus (HSV) infections were examined microscopically, electron microscopically, and immunohistochemically. Coagulative necrosis with inclusions was found in the livers and adrenal glands in all cases, as well as in various other organs, including the spleen, bone marrow, lungs, esophagus, tongue, and thymus, in some cases. Distinct hemorrhagic diathesis was found in three cases. No characteristic clinical findings, such as skin rashes or elevated titers of the antibody to HSV, were found, and clinical diagnosis was therefore difficult. In three cases isolation and typing of the causative virus were performed virologically, and type 1 HSV (HSV-1) was identified as the causative virus. Immunohistochemically, the type and distribution of the virus were evaluated in all cases with type-specific antisera to types 1 and 2 (HSV-2) antigens by the peroxidase-antiperoxidase method. In five cases the infections were found to be due to HSV-1 and in only one case to HSV-2. In the placenta in one case of HSV-2 infection, HSV antigen was demonstrated in the chorionic villi. Electron microscopic study confirmed the existence of viral particles in the placenta in that case and, thus, the possibility of a transplacental route of infection.     

Light and electron microscopic studies of retzius lines in human cervical enamel

Unaltered mature enamel and partially demineralized mature enamel from the cervical third of human permanent teeth were examined by means of transmission electron microscopy, microradiography, phase contrast and Nomarski differential interference microscopy. The Retzius lines in the outer third of the cervical enamel had a staircase configuration. The steps in the stair-case pattern formed the bases of triangular regions which were radiolucent and ultrastructurally contained fewer crystallites than the adjacent enamel. In the outer prismless layer, the Retzius lines had a curvilinear configuration and were also crystallite deficient. The structure of the Retzius lines in the inner portion of the cervical enamel was not nearly as well defined.     

Light microscopic findings on globular hyalin bodies in the human liver and its electron microscopic equivalents (author's transl)]

According to electron microscopic investigations, there is no uniform substratum and no uniform formal pathogenesis in the light microscopic appearance of globular hyalin bodies in the liver. This paper presents a survey on the different electron microscopic equivalents of the light microscopic findings of globular hyalin bodies in human liver biopsies. These electron microscopic equivalents, their occurrence, their different pathogenesis and, resulting from this, their different diagnostic and prognostic significance are described and demonstrated in detail.     

Scanning electron microscopic and X-ray microdiffractometeric studies on sialolith-crystals in human submandibular glands

The crystalline structures of 18 submandibular gland calculi were studied by radiomicrography , scanning electron microscope, and X-ray microdiffractometeric techniques. The following observations were made by SEM: Granular or globular structure was seen on the surface of all cases and pyramidal crystal in one case. In the inside, all showed lamellar pattern with amorphous nucleus in the center, and granular, plate-like and rhombohedral structures were also observed. X-ray microdiffractometeric analyses: Apatite was frequently observed in both outside and inside of the calculi. Whitlockite was next frequently detected and was seen more often in the inside. Brushite and weddellite were noted in the outside of calculi in one case each. Thus, it is suggested that brushite and weddellite were present in the front portion of calculus formation and then transformed into the more stable form e.g. apatite.     

J chain synthesis in human myeloma cells: light and electron microscopic studies

The presence of J chain in human immunocytes containing various immunoglobulin classes has already been reported and in this paper we investigated the presence of J chain in human myeloma cells using light and electron microscopy. Myeloma cells were positive for cytoplasmic J chain in thirteen cases: six of fifteen IgG myeloma, two of seven IgA myeloma, two of nine B-J myeloma and three of three primary macroglobulinaemia. None of the four with benign monoclonal gammopathy was positive for J chain. The ultrastructural localization of J chain in IgG myeloma cells was similar to that of gamma chain, i.e. around the nuclear membrane, in the endoplasmic reticulum (ER) and in the Golgi apparatus. The latter finding is compatible with the presence of J chain in the urine of the same patient. We examined the urine from nine patients with J chain-positive cells and secretion of J chain was confirmed in three patients: two with IgG myeloma and one with B-J myeloma. In noe of twelve in whom the immunocytochemical findings were negative for J chain was there evidence of urinary J chain.     

Identification of neuro-epithelial bodies in rabbit fetal lungs by scanning electron microscopy: A correlative light,transmission and scanning electron microscopic study

In the present study, neuro-epithelial bodies (NEB) were identified by scanning electron microscopy (SEM) within the bronchial epithelium of near-term rabbit fetuses. The surface features and topography of NEB were correlated by light and transmission electron microscopy. In SEM, the surfaces of NEB were easily visualized in smaller peripheral airways because of paucity of ciliated cells in these regions. The NEB formed crater-like pits, which were lined with microvilli and had smooth-surfaced non-ciliated cells around the rim. Stereo-pair photographs revealed that the latter cells protruded above adjacent bronchiolar mucosa. The SEM also revealed that NEB were preferentially located near or at bronchiolar bifurcations. This is the first report of the three-dimensional structure of pulmonary NEB. Their direct contact with the airway lumen, as well as their strategic location in bronchiolar mucosa, support the suggestion that they are intrapulmonary receptors and help to regulate air-flow in peripheral airways.     

Light and electron microscopic studies of pathologic changes in rheumatoid angitis

Pathologic changes in the small vessels in the pigmented skin of the dorsum of the fingers in rheumatoid arthritis (RA) patients with significant morning stiffness were studied by means of light and electron microscopy and histochemistry. In association with the progression of the disease, three distinct stages, 1) early or “edematous”, 2) progressive or “cellular reactive”, and 3) terminal or “sclerosing”, were observed and precisely defined. It was concluded that the evaluation of biopsy specimens from the pigmented skin in RA patients may aid in the identification of severity of the disease.     

Scanning electron microscopic observations of human fetal kidney maturing in vivo and in serum-free organ culture

A serum-free model has been developed in our laboratory enabling us to maintain human fetal kidney in culture for periods of 5 days or more. In this totally defined system, morphological integrity of these explants was shown to be preserved at both the light and the electron microscopic levels. The present work was undertaken to validate our culture model via scanning electron microscopy, a technique allowing surface observation of micromorphological features overlooked by conventional microscopy. In uncultured kidney, different developmental stages of nephron formation were identified. A sparse population of short microvilli was present on most cell apical membranes. Cell outlines were polygonal and demarcated by longer and densely packed microvilli. In proximal tubules, these microvilli were in the process of forming a brush border. In the majority of cells, one or two cilia with twisted or hooked tips projected into the capsular space or tubule lumen. Microcraters and bleb-like structures characterized the luminal membrane of many cells. The urinary papilla epithelium was composed of some ciliated principal cells but mostly of intercalated cells with either apical microplicae, microvilli, or both. Microprojections formed zipper-like intercellular junctions. In culture, ultrastructural features, including membrane pits and spherical vesicles, Were similar to those in uncultured explants. In summary, these novel observations in cultured fetal kidney indicate that ultrastructural integrity is well preserved in serum-free medium and that the present model is a valuable tool to study human nephrogenesis. © 1993 Wiley-Liss, Inc.     

Analytical and scanning electron microscopic study of intra-ocular foreign bodies

The surface characteristics of 16 intraocular foreign bodies (IOFB) were studied by scanning electron microscopy (SEM) and with an energy dispersive X-ray analyzer (EDXA). The surfaces of all the IOFBs were rough, stringy and nodular in form, and rusted with sharp edges. Many particle-like contaminants were also adhering to the surface. The nature of these particles could be determined with the use of the EDXA. The spectrum showed two peaks, oxygen and iron, indicating that iron foreign bodies are always oxidized. This study was presented at the 25th Annual Meeting of the Clinical Electron Microscopy Society of Japan, Matsumoto, September 28–30, 1993.     

In utero development and maturation of the retina of a non-primate mammal: A light and electron microscopic study of the guinea pig

Summary A light and electron microscopic examination of retinogenesis in the fetal guinea pig has revealed an early development of synapses and photoreceptor cells. Differentiation of the neural retina begins around day 23 of gestation. By 34 days the retina reaches its maximum thickness. It differentiates an inner plexiform layer in which vesicle-containing processes and primitive synapses are evident. Synaptic ribbons are found in processes of this layer by 43–45 days of gestation. An outer plexiform layer develops within the neuroblast layer at 40 days of gestation; from its first appearance the outer plexiform layer contains synapses complete with synaptic ribbons. Receptor terminals of the , paranuclear and type are present well before birth. Photoreceptor cells form inner segments by 40 days; the formation of outer segments is indicated by 45 days but not widespread until 49 days. The retina appears mature by day 51–57. It is clear that the primate is not unique in the early differentiation of its retinal synapses relative to the time of maturation of its photoreceptor cells. The potential functional capacities of precocious retinae, and the mechanisms of synapse development are discussed.Supported by Grants from the Medical Research Council.     

Scanning electron microscopic observations of surface prismless enamel formed by minute crystals in some human permanent teeth

It might have been recognized that surface prismless enamel with no prism sheaths or boundaries is formed by needle-shaped crystals in parallel arrangements and shows almost the same crystal size as the underlying prismatic enamel. This study found that some island- and band-shaped prismless enamel in third molars and dome-shaped prismless areas in the region adjacent to the partial hypoplastic enamel of a premolar were formed by minute crystals compared with the underlying prismatic enamel when observing afibrillar cementum and cementicle-like structures by scanning electron microscopy. Their minute crystals became smaller in size towards the natural enamel surface. In the band- and dome-shaped prismless enamel, the minute crystals abruptly changed to the usual-sized crystals in the underlying prismatic enamel, although the minute crystals in the dome-shaped prismless areas tended to show random arrangements. The band-shaped prismless layers might be similar to afibrillar cementum, but shallow Tomes’ process pits were present in the natural surface and no appositional laminations were observed in the fractured surface. The minute crystal formation in such prismless regions might be caused by the remarkable decline of ameloblast activity immediately after the disappearance of Tomes’ processes producing prism structures surrounded by prism sheaths during the final stage of amelogenesis.     

Polarization and electron microscopic studies on the collagen of intact and ruptured human tendons

The intact and degenerated tendons were studied by the Picrosirius polarization microscopic method and by transmission and scanning electron microscopy. In the intact tendon, type I collagen were found as sole component. In the degenerated tendon, the collagen revealed histochemical and ultrastructural aspects with are typical of collagen type III. The formation of type III collagen must be an integral part of the disease process.