The exfoliating cervical epithelial surface in dysplasia, carcinoma in situ and invasive squamous carcinoma. I. Scanning electron microscopic study.

The exfoliating epithelial surface in cone specimens of the human cervix with histologically normal epithelium, squamous metaplasia, dysplasia, carcinoma in situ and in cervical biopsies with invasive squamous carcinoma was studied by scanning electron-microscopy (SEM). A cobblestone-like surface with anisovillosis seems to herald the appearance of malignant cells on the exfoliating epithelial surface. Post-scanning histologic examination served as a diagnostic reference for the SEM findings.     

Morphometric and ultrastructural features of the mare oviduct epithelium during oestrus

Morphometric, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) investigations have displayed regional differences in the mare oviductal epithelium. The entire mucosa of the oviduct was lined with a pseudostratified epithelium, which consisted of two distinct cell types, ciliated and non-ciliated. Ciliated cells were predominant in the three different segments of the oviduct and their percentage increased from fimbriae to ampulla and significantly decreased in the isthmus. SEM revealed in the infundibulum finger-like mucosal folds, some of them interconnected, in the ampulla numerous and elaborated branched folds of the mucosa, whereas the isthmus displayed a narrow lumen, short and non-branched mucosal folds. In the ampulla and isthmus the majority of non-ciliated cells showed apical blebs provided or not of short microvilli. TEM displayed different ultrastructural features of ciliated and non-ciliated cells along the oviduct. Isthmus ciliated cells presented a more electron-dense cytoplasm than in infundibulum and ampulla cells and its cilia were enclosed in an amorphous matrix. The non-ciliated cells of infundibulum did not contain secretory granules but some apical endocytic vesicles and microvilli coated by a well developed glycocalyx. Non-ciliated cells of ampulla and isthmus contained secretory granules. Apical protrusions of ampulla displayed two types of secretory granules as well as occasional electron-lucent vesicles. Isthmus non-ciliated cells showed either electron-lucent or electron-dense cytoplasm and not all contained apical protrusions. The electron-dense non-ciliated cells displayed microvilli coated with a well developed glycocalyx. Three types of granules were observed in the isthmus non-ciliated cells. The regional differences observed along the epithelium lining the mare oviduct suggest that the epithelium of the each segment is involved in the production of a distinctive microenvironment with a unique biochemical milieu related to its functional role.     

Fine structural studies of rat seminal vesicle in castrated and intact animals following estrogen treatment.

The effect of estradiol and/or testosterone upon secretion by seminal vesicle in castrated and intact rats was assessed in young adult Sprague-Dawley rats, using light microscopy (LM), transmission (TEM) and scanning (SEM)electron microscopy. Hormones were injected daily for ten days beginning ten days after castrations were performed. The normal rat seminal vesicle, as revealed by SEM, was characterized by a large saccular lumen with highly folded walls. Cell surfaces were covered with microvilli, or occasionally displayed a protruding, ruffled surface, sparsely covered with short microvilli. Cytology was normal in testosterone-treated animals. Estradiol treatment of castrated animals stimulated secretion by seminal vesicle epithelial cells as evidenced by the presence of normal secretory bodies, the presence of RER, and moderately hypertrophied Golgi complexes. These glands were not heavier than were glands from castrated, untreated animals, although the epithelial cells were significantly taller. Secretion was maintained in intact animals treated with estradiol, although glands were smaller and epithelial height was reduced. Estradiol and testosterone treatment in combination did not appear to have an additive effect on secretion, weight of the gland, or epithelial height. The following results support the hypothesis that estrogen-induced prolactin synthesis and release may be involved in the mechanism by which estradiol effected stimulation of seminal vesicle epithelium. Prolactin-treated, castrated animals exhibited focal areas of stimulated epithelium. In hypophysectomized animals (untreated controls), the seminal vesicle epithelium retained some secretory bodies and secretory fluid in the glandular lumen; epithelial height was taller than that in castrated controls. Estrogen treatment reduced the epithelial height to that of castrated controls; there was no evidence of secretion. This suggests that in the absence of anterior pituitary hormones, including prolactin, the stimulatory effect of estradiol on seminal vesicle epithelium was nullified. In adrenalectomized/castrated animals, estradiol treatment stimulated secretion in seminal vesicle epithelium just as in non-adrenalectomized/castrated animals. This indicates that the adrenal gland plays a non-essential role in the action of estrogen on seminal vesicle epithelium.     

DNA profiles in dysplasia and carcinoma of the human esophagus

The nuclear DNA content was microspectrophotometrically measured in 16 resected esophagi having dysplasia, carcinoma in situ and/or early invasive squamous carcinoma. First, the epithelial thickness in (1) normal squamous esophageal epithelium and (2) dysplasia-carcinoma in situ areas was divided into three equal compartments (i.e., basal-parabasal, intermediate and superficial) in five cases. In the normal epithelium, while some of the nuclei in basal-parabasal normal squamous cells had elevated DNA values (corresponding to the natural DNA replication in these cells), intermediate and superficial (nonreplicating) normal squamous cells showed a more definite clustering about the 2c value. In the nonnormal epithelium, the percentage of cells with DNA levels exceeding the normal tetraploid value was highest for the intermediate zone. Therefore, in all 16 cases, normal intermediate cells were measured as internal controls, against which the DNA levels of cells in the intermediate compartment in the areas of dysplasia and/or carcinoma in situ were compared. In areas of dysplasia, two different DNA patterns were observed: one clustering around the normal diploid region and the other with aneuploid values. While the former corresponded to some of the lesions considered by conventional histologic examination to be slight and moderate dysplasias, the aneuploid pattern corresponded to the remaining slight and moderate dysplasias as well as to the severe dysplasias. The possibility that "diploid dysplasias" are reactive (i.e., nonneoplastic) lesions due to chronic inflammation or are "dormant" nonprogressive dysplasias, while aneuploid dysplasias are more aggressive lesions, seems to be substantiated by the fact that all areas with carcinoma in situ or with microinvasive squamous carcinoma had aneuploid nuclei.     

Building the brush border,one microvillus at a time

Microvilli are actin bundle-supported surface protrusions assembled by diverse cell types to mediate biochemical and physical interactions with the external environment. Found on the surface of some of the earliest animal cells, primordial microvilli likely contributed to bacterial entrapment and feeding. Although millions of years of evolution have repurposed these protrusions to fulfill diverse roles such as detection of mechanical or visual stimuli in inner ear hair cells or retinal pigmented epithelial cells, respectively, solute uptake remains a key essential function linked to these structures. In this mini review, we offer a brief overview of the composition and structure of epithelial microvilli, highlight recent discoveries on the growth of these protrusions early in differentiation, and point to fundamental questions surrounding microvilli biogenesis that remain open for future studies.     

Electronmicroscopic observations on epidermoid (squamous cell) carcinomas of the lung

Five epidermoid (squamous cell) carcinomas of the lung histopathologically diagnosed were ultrastructurally analysed; special attention was given to the poorly differentiated-immature areas of proliferation. Wide intercellular spaces between irregular cytoplasms with protrusions and microvilli, a high incidence of indentations of nuclear membranes, a large amount of nuclear bodies, shape, size and structure anomalies of mitochondria, a great number of desmosomes and of tonofilaments and tonofibril bundles and their relations with desmosomes and with the finger-like cytoplasmic expansions were noticed. A few secretory granules were also present in these poorly differentiated-immature areas of epidermoid carcinomas of the lung.     

乳腺浸润性微乳头状癌的研究现状

乳腺浸润性微乳头状癌(IMPC)是乳腺浸润性癌的一种特殊类型,其发生率低,临床表现及影像学特征与普通的乳腺浸润性导管癌没有显著区别。这种病理类型可与普通浸润性导管癌混合出现,也可表现为单纯的浸润性微乳头状癌。但浸润性微乳头状癌具有独特的组织学形态及分子结构,决定了其病理学分级较高、易于发生淋巴结转移的侵袭性生物学行为特点。多数浸润性微乳头状癌在影像学上表现为边缘不清的不规则肿块影,常伴有微小钙化。其特征性病理形态为细胞膜上皮抗原(EMA)在肿瘤细胞簇外周的细胞和基质中腔隙边缘特异性染色,同时显微镜下瘤细胞表面发现微绒毛结构,说明了瘤细胞簇周围的空隙样结构实际上是管状腔隙,瘤细胞呈"极向倒转"方式排列。IMPC具有高度淋巴血管浸润倾向,局部复发率高,是一种预后较差的类型。本文对近年来关于乳腺浸润性微乳头状癌的研究进展进行了综述。     

Mucin-producing bronchioloalveolar-cell carcinoma. With special reference to a characteristic structure revealed by phosphotungstic acid-hematoxylin staining

In four cases of bronchioloalveolar-cell carcinoma of the mucin-producing type, the cells were characterized electron microscopically by cored microvilli seen on the free surface of the tumor cells, structures that corresponded well to the phosphotungstic acid-hematoxylin (PTAH) stained structures seen by light microscopy in histologic specimens. The exfoliative cytology specimens contained corresponding PTAH-stained structures on the cell surfaces, namely, a prominent cell membrane with a "beaded" or "peg-like" configuration and, in places, a "feathery" nature, findings quite dissimilar to the surfaces of other well-differentiated adenocarcinoma cells. The cytologic specimens also exhibited characteristic nuclear indentations and tightly connected cell groupings. These results indicate the existence of a type of bronchioloalveolar-cell carcinoma not derived from type II alveolar epithelial cells or Clara cells.     

A Scanning Electron Microscopic Study on the Thyroid Follicle of the Hagfish Eptatretus burgeri

The external form of the follicles was mostly spherical or oval and the large oval follicles reached more than 300 times 180 μm in size. Cytoplasmic inclusions of various sizes were observed in the follicular epithelium. Follicles were composed of hexagonal epithelial cells, and on the apical surface of the cells many microvilli were found (380–500 microvilli per cell) with globular or amorphic cytoplasmic protrusions. In a few cells a central cilium was also observed. From these results a relationship between thyroid structure and function in the hagfish is discussed.     

Surface characteristics of isopod digestive gland epithelium studied by SEM

The structure of the digestive gland epithelium of a terrestrial isopod Porcellio scaber has been investigated by conventional scanning electron microscopy (SEM), focused ion beam–scanning electron microscopy (FIB/SEM), and light microscopy in order to provide evidence on morphology of the gland epithelial surface in animals from a stock culture. We investigated the shape of cells, extrusion of lipid droplets, shape and distribution of microvilli, and the presence of bacteria on the cell surface. A total of 22 animals were investigated and we found some variability in the appearance of the gland epithelial surface. Seventeen of the animals had dome-shaped digestive gland “normal” epithelial cells, which were densely and homogeneously covered by microvilli and varying proportions of which extruded lipid droplets. On the surface of microvilli we routinely observed sparsely distributed bacteria of different shapes. Five of the 22 animals had “abnormal” epithelial cells with a significantly altered shape. In three of these animals, the cells were much smaller, partly or completely flat or sometimes pyramid-like. A thick layer of bacteria was detected on the microvillous border, and in places, the shape and size of microvilli were altered. In two animals, hypertrophic cells containing large vacuoles were observed indicating a characteristic intracellular infection. The potential of SEM in morphological investigations of epithelial surfaces is discussed.     

The role of the mesenchyme in the development of the early primordium of the respiratory epithelium

Development of respiratory epithelium (RE) rudiment was studied in tissue culture after removal of mesenchyme (M) and respiratory tract (RT) in 13 days old embryos of A and C57BL mice. During long-term cultivation of intact RT, organotypic structures (branching bronchioles, alveolus-like cavities) developed. No epithelial organotypic structures developed in the presence of single M cells; explants were represented by layers of cubic epithelium. During long-term cultivation foci of atypical growth consisting of intensively proliferating basophilic cells with high nucleocytoplasmic ratio appeared in these explants. Regions of planocellular metaplasia with or without keratinization could be found in these foci. The frequency of atypical proliferates depended on the strain of donor mice and on the region of the explanted RT.     

Ultrastructural and ultracytochemical study of the middle ear epithelium in the chicken,Gallus gallus domesticus

The fine structure of the epithelium lining the tympanic cavity of the chicken was studied by TEM and SEM. In addition, the distribution of nonspecific esterase activity in the epithelium was investigated by TEM. Ultrastructural study revealed the presence of disk-like apical protrusions of the epithelial cells, previously not observed in other cell types. The protrusions contained some cytoplasmic organelles and were characterized by a ring-shaped thickening around their periphery. The ring was made up of a granulo-filamentous material. Our observations clearly indicate the existence of an apocrine secretory mechanism, consisting of a progressive detachment of disk-like protrusions from the apex of the epithelial cells. The ultracytochemical study demonstrated nonspecific esterase activity on the epithelial surface and in the secretory vesicles. We propose that nonspecific esterase is a marker for middle ear surfactant in birds.     

Fine needle aspiration cytology of invasive micropapillary carcinoma of the breast: review of cases in a three-year period.

OBJECTIVE: To describe the fine needle aspiration cytology findings of invasive micropapillary carcinoma and correlate them with the histologic appearance. STUDY DESIGN: We reviewed the cytologic features of three cases of pure invasive micropapillary carcinoma in the files of Pamela Youde Nethersole Eastern Hospital from 1998 through 2000. Immunohistochemical study for epithelial membrane antigen was performed retrospectively on the cell block sections. Ultrastructural examination was also carried out on one of the cases. RESULTS: Two of the tumors were at pathologic stage II, and the remaining case was at stage III. Ipsilateral axillary lymph node metastases with similar morphology were seen in two of them. Cytologically, the smears were of moderate cellularity and composed of three-dimensional tumor cell balls, abortive and sometimes branching papillae, angulated tumor cell clusters, morules and occasional acini. Some of the tumor cell balls possessed scalloped borders. Focally, the tumor morules clustered together and were separated from each other by small, slitlike spaces. A small number of isolated malignant cells was also present in the background. The cell block sections showed mainly dispersed acini of tumor cells. The "reverse polarity" highlighted in histologic sections by immunohistochemical study for epithelial membrane antigen was not consistently demonstrated in the cell block material. Ultrastructural examination confirmed the focal presence of surface microvilli on the periphery of the tumor cell morules. CONCLUSION: Invasive micropapillary carcinoma of the breast possesses some subtle but distinctive cytologic features. With the help of cell block morphology and ancillary techniques, the preoperative suspicion of this rare subtype of ductal carcinoma, which carries a high propensity for lymphatic permeation, is possible.     

The many faces of actin: matching assembly factors with cellular structures

Actin filaments are major components of at least 15 distinct structures in metazoan cells. These filaments assemble from a common pool of actin monomers, but do so at different times and places, and in response to different stimuli. All of these structures require actin-filament assembly factors. To date, many assembly factors have been identified, including Arp2/3 complex, multiple formin isoforms and spire. Now, a major task is to figure out which factors assemble which actin-based structures. Here, we focus on structures at the plasma membrane, including both sheet-like protrusive structures (such as lamellipodia and ruffles) and finger-like protrusions (such as filopodia and microvilli). Insights gained from studies of adherens junctions and the immunological synapse are also considered.     

A scanning electron microscopic study of the luteo-follicular complex. II. Events leading to ovulation.

Morphological changes on the ovarian surface of different mammals both before and during ovulation have been examined by scanning electron microscopy. Preovulatory follicles were blisterlike structures that protruded markedly from the ovarian surface. Basal areas of preovulatory follicles were covered with polyhedral cells containing numerous microvilli, whereas on the lateral surfaces, superficial cells were elongated and possessed few microvilli. At the apex of the follicle, cells were very flattened and possessed few microvilli, which were present only in regions of intercellular contact. In some apical areas, cells appeared to be degenerating, whereas in other regions, groups of cells had "sloughed off." In addition, a fluidlike material was observed to exude from intercellular spaces of the superficial epithelium and to cover some apical cells. By transmission electron microscopy, the same fluidlike material was observed to (1) infiltrate the connective tissue of the tunica albuginea, (2) accumulate under the basal lamina, and (3) distend intercellular spaces of the superficial epithelium. Just prior to ovulation, large, irregular areas of the apex were ruptured and the oocyte, covered with a large amount of fluid, appeared to emerge from the follicle. At ovulation, the oocyte was not completely covered with follicle cells and the zona pellucida was clearly evident. The surface of the zona was quite irregular and contained numerous infoldings, channels and crypts. Follicle cells had polyhedral or star shapes and possessed large cytoplasmic evaginations that obliquely penetrated the zona. Both the zona pellucida and corona cells were covered with a fine layer of granular material. The SEM results and parallel TEM observations suggest that a local increase of fluids (edema) may be an important factor in the final decomposition of the distended and weakened apex of the preovulatory follicle. In addition, the participation of follicle cells, smooth muscle cells and the oviduct in the escape of the oocyte from the ruptured follicle is discussed.     

Histology and ultrastructure of the gut epithelium of the neotenic cave salamander, Proteus anguinus (Amphibia, Caudata)

Histological, histochemical, and ultrastructural features of the gut of the European endemic cave salamander Proteus anguinus were studied. The gut is a relatively undifferentiated muscular tube lined with a simple columnar epithelium containing numerous goblet cells. The mucosa and underlying lamina propria/submucosa are elevated into a number of high longitudinal folds projecting into the lumen. The enterocytes are covered apically with uniform microvilli. Irregularity in the arrangement of microvilli was observed. Occasionally, irregular protrusions of the cytoplasm appear between groups of microvilli. Pinocytotic activity occurs at the bases of the intermicrovillous space. Mitochondria are numerous in the apical cytoplasm and basally beneath the nuclei. The supranuclear cytoplasm contains most of the cell organelles. The lateral plasma membranes of adjacent cells interdigitate and are joined by junctional complexes. The periodic acid-Schiff (PAS) reaction, indicating neutral mucosubstances, is positive only in the apical brush border of enterocytes and in goblet cells. The goblet cells also stained with Alcian blue (AB), at pH 2.5, thus revealing the presence of carboxylated glycosaminoglycans. Compact aggregations of AB- and PAS-negative cells are situated directly below the epithelium. Mitotic figures are present in individual clusters of cells. The fine structure of cells in these clusters indicated that these cells could be responsible for renewal of intestinal epithelium. Numerous endocrine-like cells could also be seen. The closely packed smooth muscle cells and amorphous extracellular material with collagen fibrils constitute a net-like structure under the basal lamina that is very closely associated with the epithelium. There are numerous acidophilic granular cells between epithelial cells, in the lamina propria/submucosa, and between cells aggregations. They seem to be associated with nematode infections and possibly constitute a humoral defense mechanism.     

Characterization of morphological and cytoskeletal changes in MCF10A breast epithelial cells plated on laminin-5: comparison with breast cancer cell line MCF7

The extracellular matrix regulates functional and morphological differentiation of mammary epithelial cells both in vivo and in culture. The MCF10A human breast epithelial cell line is ideal for studying these processes because it retains many characteristics of normal breast epithelium. We describe a distinct set of morphological changes occurring in MCF10A cells plated on laminin-5, a component of the breast gland basement membrane extracellular matrix. MCF10A cells adhere and spread on laminin-5 about five times more rapidly than on fibronectin or uncoated surfaces. Within 10 minutes from plating on laminin-5, they send out microfilament-rich filopodia and by 30 minutes acquire a cobblestone appearance with microfilaments distributed around the cell periphery. At 90 minutes, with or without serum, > 75% of the MCF10A cells plated on laminin-5 remain in this stationary cobblestone phenotype, while the remainder takes on a motile appearance. Even after 18 hours, when the culture is likely entering an exponential growth phase, the majority of cells maintain a stationary cobblestone appearance, though motile cells have proportionally increased. In contrast, the fully transformed, malignant human breast epithelial cells, MCF7, never acquire a stationary cobblestone appearance, do not organize peripheral microfilaments, and throughout the early time points up to 120 min appear to be constantly motile on laminin-5. We propose that changes in morphology and microfilament organization in response to laminin-5 may represent a benchmark for distinguishing normal vs. malignant behavior of epithelial cells derived from the mammary gland. This may lead to better model systems for studying the interactions between breast epithelium and the basement membrane extracellular matrix, which appear to be deregulated in processes like carcinogenesis and metastasis.     

Characterization of Morphological and Cytoskeletal Changes in MCF10A Breast Epithelial Cells Plated on Laminin-5: Comparison with Breast Cancer Cell Line MCF7

The extracellular matrix regulates functional and morphological differentiation of mammary epithelial cells both in vivo and in culture. The MCF10A human breast epithelial cell line is ideal for studying these processes because it retains many characteristics of normal breast epithelium. We describe a distinct set of morphological changes occurring in MCF10A cells plated on laminin-5, a component of the breast gland basement membrane extracellular matrix. MCF10A cells adhere and spread on laminin-5 about five times more rapidly than on fibronectin or uncoated surfaces. Within 10 minutes from plating on laminin-5, they send out microfilament-rich filopodia and by 30 minutes acquire a cobblestone appearance with microfilaments distributed around the cell periphery. At 90 minutes, with or without serum, >75% of the MCF10A cells plated on laminin-5 remain in this stationary cobblestone phenotype, while the remainder takes on a motile appearance. Even after 18 hours, when the culture is likely entering an exponential growth phase, the majority of cells maintain a stationary cobblestone appearance, though motile cells have proportionally increased. In contrast, the fully transformed, malignant human breast epithelial cells, MCF7, never acquire a stationary cobblestone appearance, do not organize peripheral microfilaments, and throughout the early time points up to 120 min appear to be constantly motile on laminin-5. We propose that changes in morphology and microfilament organization in response to laminin-5 may represent a benchmark for distinguishing normal vs. malignant behavior of epithelial cells derived from the mammary gland. This may lead to better model systems for studying the interactions between breast epithelium and the basement membrane extracellular matrix, which appear to be deregulated in processes like carcinogenesis and metastasis.     

Peritrophic membrane structure and formation of larvalTrichoplusia niwith an investigation on the secretion patterns of a PM mucin

Peritrophic membrane or matrix (PM) secretion and formation patterns were examined in the cabbage looper larvae (Trichoplusia ni[Hubner]) by transmission and scanning electron microscopy (SEM). PM first became visible in the lumen between tips of the microvilli and the stomodeal valves as a single layered fibrous structure that became more compact in appearance in the middle and posterior mesenteron. In the anterior mesenteron, nascent PM was visible within the brush border as a fibrous linear structure that contained both the major PM matrix protein, invertebrate intestinal mucin (IIM) and chitin-containing structures. Even though delamination events were confined to the anterior mesenteron, IIM was secreted by columnar epithelial cells throughout the length of the mesenteron. SEM of the midgut epithelium revealed PM covering individual epithelial cells.     

Anatomic basis of endometrial cytology

A comparative cytologic and histologic study on 700 hysterectomy specimens showed that the cytologic evaluation of exfoliated cells from the uterine cavity did not correspond to the findings of the histologic examination of the endometrium in about 33% of sexually mature and 30% of postmenopausal women. The findings of both methods did not always coincide because the epithelial cells in the imprints or smears and the epithelial cells lining the glands in the histologic specimens belonged to structures that anatomically have little in common, one being superficial epithelium of the endometrium and the other being the glandular epithelium in the deep layers of the mucosa. This explains the false-negative results in the cytologic examination of the endometrium, especially in cases of glandular hyperplasia and early carcinoma, in which the foci of proliferation are initially covered by small and inactive surface epithelial cells and are inaccessible to cytologic investigation. False-positive cytologic results may occur in cases of irritated surface epithelium in chronic endometritis; this may also happen in women using an intrauterine device, during estrogen therapy, in regenerating mucosa after desquamation or curettage, in early pregnancy and after spontaneous abortion.