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PubMed1963

The size of the cellulose microfibril.

Recently the lateral width of the cellulose microfibril has been estimated as 30 A rather than about 150 to 200 A, by extrapolation of data from model shadowing experiments. The difference was attributed to a layer of metal deposited during shadowing. However, direct photographs of the same microfibrils parallel and perpendicular to the direction of shadowing, of unshadowed portions of microfibrils compared with shadowed portions of the same microfibrils, of silver-stained unshadowed microfibrils, and of unshadowed, unstained segments of microfibrils give no evidence of a layer of metal of this thickness in material shadowed under normal conditions. Furthermore, the evidence for microfibril strands of about 35 A in width from negative-staining experiments is subject to a bias from the form of the filaments and from variable positive adsorption of phosphotungstic acid by cellulose. Consequently, the conclusion that the true lateral width of native cellulose microfibrils is about one-fifth of the presently accepted value is not yet justified by unequivocal direct experimental evidence.

Acetobacter↗

PubMed2003

Clinical relevance of immunohistochemical staining for ecto-AMPase and ecto-ATPase in chronic allograft nephropathy (CAN).

INTRODUCTION: Chronic allograft nephropathy (CAN) is a major cause of deterioration of kidney function in transplanted patients. It is thought that glomerular ischaemia may contribute to glomerular dysfunction and proteinuria in these subjects. As reduced expression of glomerular ecto-ATPase concurrent with upregulation of glomerular ecto-AMPase activity is associated with local ischaemia, we compared the expression of these glomerular ecto-enzymes in kidney biopsies from subjects with CAN or with acute rejection vs normal human kidney tissue. METHODS: Kidney biopsies in comparison with normal kidney tissue samples (n = 10) were studied from subjects with CAN (n = 6), acute interstitial rejection (n = 13), acute vascular rejection (n = 3), or subjects whose biopsies were histologically difficult to classify (n = 8). Cryostat sections (4 micro m) were stained for ecto-ATPase using standard procedures. For the demonstration of ecto-AMPase activity, conventional enzyme histochemistry was used. Reaction product of individual sections was quantified using computerized image analysis. RESULTS: The results clearly show decreased expression of glomerular ecto-ATPase in combination with increased glomerular ecto-AMPase in all biopsies from subjects with CAN vs normal kidney tissue (P < 0.001). Although to a lesser extent, this staining pattern was also observed in patients with vascular rejection as well as in subjects whose biopsies were histologically difficult to classify (P < 0.01), while biopsies from subjects with interstitial rejection and normal control tissue stained negative for glomerular ecto-AMPase. CONCLUSION: In CAN diminished glomerular ecto-ATPase expression occurs in association with significantly enhanced activity of glomerular ecto-AMPase. This is a strong indication for ischaemic injury of the glomerular microvasculature. As positive staining for ecto-AMPase in acute rejection episodes may be an important sign for long-term prognosis, we feel that screening of biopsies from individual subjects for glomerular ecto-AMPase activity should be considered.

Adenosine Triphosphatases↗

PubMed1991

Regional heterogeneity in human corneal and limbal epithelia: an immunohistochemical evaluation.

The authors studied the distribution of specific keratins within the superior, inferior, medial, and lateral regions of human limbus and cornea to determine whether the limbal epithelium exhibits regional heterogeneity in its microstructure. A corneal epithelial basic keratin (K3), recognized by monoclonal antibody AE5, was immunohistochemically undetectable in the basal layers of the limbus in these four regions, but was seen in all layers in the central cornea. The pattern of immunostaining with another monoclonal antibody, AE1, which recognizes several acidic keratins, was complementary to AE5 staining in that AE1 recognized a similar heterogeneity in the limbal epithelial cells. AE1 immunoreacted with the basal cells of the limbus, but not those of the central corneal epithelium. Limbal characteristics, as defined by AE1-positive and AE5-negative staining, extended deeply into peripheral cornea in the superior and inferior regions, but to a lesser extent in the lateral and medial regions. The broader regions of epithelium with limbal characteristics in the superior and inferior regions raises the possibility that these regions play an important role in corneal epithelial maintenance and wound healing.

Aged↗

PubMed1999

Clinical application of proliferating cell nuclear antigen, oncoprotein p53 and tumor front grading analysis in patients operated on for laryngeal cancer.

The authors assessed proliferating cell nuclear antigen (PCNA), p-53 oncoprotein and morphologic tumor front grading (TFG) in patients with advanced squamous cell carcinoma (SCC), of the larynx and a poor prognosis and tried to find a correlation with tumor stage, the Broders grading system, local and neck lymph node metastases, as well as nodal and local recurrences. In addition, utility of the parameters investigated was evaluated in developing a prognostic factor model, using uni- and multivariate Cox regression analysis. Included in this study were 54 patients (mean age 57 years +/- 8.6). PCNA-positive staining was found in all but one patient with advanced disease, while p-53 stained positively in only 24 subjects (44.4%). The PCNA index ranged from 4.6 to 59.0% (mean, 23.4 +/- 11. 0) and the p-53 index varied from 4.0 to 42.0% (mean, 17.2 +/- 8.6). The TFG score ranged from 9 to 23 points (mean, 15.1 +/- 3.2). PCNA, p-53 and TFG were found to be the markers that provided significant additional information about the biological behavior of tumor cells. The high variability of the results (PCNA, p-53) and high percentage of negatively stained cells (p-53) reduced their application in clinical use. PCNA correlated with tumor grade, G (r = 0.38; P < 0. 01), but negatively with nodal (N) disease(r = -0.37; P < 0.01). The mean values of PCNA and p-53 index were higher in the subgroup with local recurrences. Our present attempt to develop a useful prognostic factor model failed.

Adult↗

PubMed1985

Are there knobs on energy transducing membranes in situ?

It is argued here that the projections which are frequently seen on the matrix side of the mitochondrial inner membranes and which are characterized as globules or spherical projections or as knob-on-stalks are an artifact of the preparation and/or of the staining of the submitochondrial particles or mitochondria. In sectioned or freeze-fractured preparations of intact cells or mitochondria, the externalized spheres are rarely seen on the membranes. They are, however, almost always seen on fragmented preparations, especially if they have been negatively stained with phosphotungstate.

Animals↗

PubMed2006

c-erbB-2 (HER-2/neu) immunohistochemistry in invasive breast cancer: is there concordance between standard sections and tissue microarrays?

AIMS: Immunohistochemical detection of the 185-kDa transmembrane glycoprotein product of the proto-oncogene c-erbB-2 (also known as HER-2/neu), located on chromosome 17q21, is a well established method of evaluation in invasive breast cancer. This investigation is currently performed on standard sections cut from the tumour containing paraffin block. It is uncertain if concordant results can be obtained on tissue microarray (TMA) sections, a high throughput technique that is particularly advantageous in research and validation protocols. Our aim in this study was to compare the results of c-erbB-2 immunoexpression in standard sections of invasive breast cancers with those of TMAs. METHODS: Standard sections and TMAs constructed from archival paraffin-embedded breast cancers of 184 patients who had surgery in Singapore General Hospital during the period 1998-2002 were subjected to immunohistochemistry using the commercial antibody (A0485, Dako). c-erbB-2 over-expression was evaluated according to cytoplasmic membrane staining intensity, which was defined as 2+ and 3+ staining. RESULTS: Over-expression of c-erbB-2 protein was found in 21.2% (39/184) and 18.6% (34/183) of cases on standard sections and TMAs, respectively. There was substantial agreement between these two types of sections (k = 0.724) when positive and negative staining was considered. CONCLUSION: Immunohistochemistry on TMAs for c-erbB-2 expression in breast cancer is a reliable alternative to that performed on routine standard sections, as it is both cost effective and time efficient, especially in a research setting.

Breast Neoplasms↗

PubMedDate not supplied

Detection of non-papillary, non-invasive transitional cell G1 carcinoma as revealed by increased DNA instability and other cancer markers.

The method to reveal DNA-instability as demonstrated by immunohistochemical staining with anti-cytidine antibody after acid hydrolysis (DNA-instability test) was used as a marker of malignancy. The test was applied to paraffin-embedded sections taken from 15 urinary bladders, renal pelvic cavities, and ureters bearing multiple carcinoma in situ (CIS) and totally 31 papillary urothelial cancers. The serial sections of the same tissues were also subjected to immunohistochemical staining for PCNA, p53, DFF45, and VEGF. The DNA-instability test was positive in 100% cancer lesions irrespective of the grades, and apparently normal urothelium, and hyperplastic and dysplastic urothelial lesions also showed the areas with clones positively stained with DNA-instability testing, and the percent numbers of positive areas in them were 28.3%, 37.7%, and 61.5%, respectively. These clones, which were present in apparently normal urothelium and in hyperplastic and dysplastic urothelial lesions, showed higher percent values of PCNA-positive-cells, in comparison to the values estimated in the areas with negatively stained DNA-instability testing, and the former values were statistically not different from those in carcinoma lesions. Furthermore, the percent numbers of areas positive for p53, DFF45, and VEGF, with positive DNA-instability testing were also much higher than those with negative DNA-instability testing in apparently normal urothelium, and hyperplastic and dysplastic urothelial lesions, and the former values were again comparable to those in cancer lesions with no statistical differences. These clones were regarded as already being malignant and should be the direct precursors of progressed cancer lesions. They will make progression through two different pathways, one to papillary non-invasive G1 cancers by neovascularization induced by paracrine secretion of VEGF, and another to flat CIS G2 without secretion of VEGF; thus the clones should be regarded as non-papillary, non-invasive Gl TCC, or CIS G1. It should be always taken into account that the probability for apparently normal urothelium, and hyperplastic and dysplastic urothelial lesions to contain cancer clones, will be high already, especially in tumor-bearing bladders.

Biomarkers, Tumor↗

PubMed1984

Immunohistochemical localization of T antigen-like substance in benign hyperplasia and adenocarcinoma of the prostate.

Peanut agglutinin was used in a lectin-anti-lectin immunoperoxidase technique to assess the status of T antigen-like substance in histological sections of benign hyperplasia and adenocarcinoma of the prostate. Of 30 benign lesions 26 (86.7 per cent) had negative staining in the glandular epithelia and 4 showed uneven staining of the epithelial cells in a small proportion of the glands. Additionally, 15 of 30 benign lesions (50 per cent) had positive staining restricted to the basal myoepithelial cells in a variable proportion of the glands. All benign lesions demonstrated the presence of normal cryptic T antigen after neuraminidase digestion. Of 25 adenocarcinomas 14 (56 per cent) were positive and 7 (25 per cent) were negative for T antigen but demonstrated the presence of normal cryptic T antigen after neuraminidase digestion, and 4 (16 per cent) were negative for T and cryptic T antigens. Of 8 grade 1, 9 grade 2 and 8 grade 3 tumors, and 9 tumors from patients with bone metastases 3 (37.5 per cent), 8 (88.9 per cent), 7 (87.5 per cent) and 7 (77.8 per cent), respectively, were positive for T antigen or negative for T and cryptic T antigens. The results show a correlation between the status of T antigen-like substance and tumor grade as well as metastasis in patients with prostatic carcinoma.

Adenocarcinoma↗

PubMed1976

Motility in normal and filamentous forms of Rhodospirillum rubrum.

By suitable choice of medium, Rhodospirillum rubrum has been grown both in normal (length 2 mum) and filamentous (length up to 60 mum) forms. Both forms were highly motile, and negatively-stained preparations showed bipolar flagellated cells, with an average of seven flagella at each pole. Motion consisted of a series of runs and tumbles, the ditribution of run time-lengths being Poissonian. Both forms tumbled in response to dark shock and showed negative chemotaxis to oxygen. The observation that the motility pattern was very similar in normal and filamentous forms makes chemical control of tumbling unlikely and favours a system involving membrane potentials.

Chemotaxis↗

PubMed1995

Bcl-2 oncoprotein is widespread in lymphoid tissue and lymphomas but its differential expression in benign versus malignant follicles and monocytoid B-cell proliferations is of diagnostic value.

The distribution of Bcl-2 oncoprotein was studied immunohistochemically in formaldehyde-fixed and paraffin-embedded reactive and neoplastic lymphoid tissue. The potential of Bcl-2 for the differential diagnosis of follicular lesions was emphasized, and the results on follicular lesions were correlated with those of polymerase chain reaction (PCR) assay of the immunoglobulin heavy chain gene rearrangement. In hyperplastic lymphoid tissue, Bcl-2 reactivity was widespread, including germinal center surroundings, scattered cells within the germinal centers, and the T-cell areas in general. Distinctively negative lymphoid populations included the majority of germinal center cells, and the negative staining pattern was maintained in cases of florid hyperplasia. In contrast, follicular lymphoma cells were consistently Bcl-2 positive. The immunohistochemical Bcl-2 reactivity of lymphoma follicles correlated with the clonal PCR amplification pattern of the immunoglobulin heavy chain gene; all Bcl-2-negative hyperplasias revealed a non-clonal pattern. Clusters of monocytoid B cells were Bcl-2 negative, whereas monocytoid B-cell lymphomas and closely related MALT lymphomas were positive. All other small cell non-Hodgkin's lymphomas of B-cell types showed nearly uniform Bcl-2 reactivity, whereas large cell B-cell lymphomas were variably positive (74%). In Hodgkin's cells, Bcl-2 reactivity was seen in the neoplastic populations of most cases of nodular sclerosis and mixed cellularity types, whereas the L&H and Reed-Sternberg cells in lymphocyte predominance Hodgkin's disease were negative in most cases. Bcl-2 immunohistochemistry thus appears very valuable in the differential diagnosis of follicular hyperplasia and neoplasia, and it may help to distinguish between reactive and neoplastic monocytoid B cells. However, Bcl-2 immunohistochemistry is not useful in the subtyping of B-cell lymphomas.

Hodgkin Disease↗

PubMed1982

New technique of kidney tissue processing for immunofluorescence microscopy: formol sucrose/gum sucrose/paraffin.

Present methods of tissue processing for immunofluorescence other than snap freezing have generally been unsatisfactory. We have developed a new kidney tissue holding and processing technique suitable for immunofluorescence, histochemical, and light microscopic analysis of the same specimen. Fifty kidney biopsies containing glomeruli in formol sucrose/gum sucrose/paraffin (FSGSP) were deparaffinized, digested with 0.1 per cent pronase, and compared both qualitatively and quantitatively with snap frozen tissue. Agreement between the two methods was very good (86 to 98 per cent), and total accuracy of FSGSP in detecting deposits ranged from 94 to 100 per cent (IgG, 94 per cent; IgM, 96 per cent; IgA, 98 per cent; fibrin, 96 per cent; Clq, 100 per cent; C3, 98 per cent). The intensity of staining based on a 0 to 4+, 11-point scale, was comparable. When both methods were positive, the intensity of staining in the same pattern was within 1 of frozen in 85 per cent of FSGSP cases and less than frozen by more than 1 in only 7.7 per cent. The overall intensity of FSGSP was slightly greater than frozen when not identical. Negative staining discrepancies were of trace amount in 73 per cent of cases with only 12 per cent differing by a quantity of 2 or greater for six stains combined. Qualitative analyses of IgE, Tamm-Horsfall protein, light chains, and alpha-2-macroglobulin were similar for the two methods. Tissue antigenicity was preserved for long periods of time in both the holding solution and paraffin. Histochemical staining for nonspecific esterase and routine light microscopic sections was comparable to regularly processed paraffin-embedded tissue. Compared with frozen methods, FSGSP was more sensitive, background was lower, few false-positives were present, resolution at high-power was better, and both linear and granular deposits were detected. This new processing method has significant advantages relative to previously described techniques and should have wide applicability to both clinical and research needs.

Evaluation Studies as Topic↗

PubMed1993

Bcl-2 protein in centrocytic lymphoma; a paraffin section study.

Bcl-2 is an inner mitochondrial membrane protein which blocks apoptosis. Although present in many B cells, the vast majority of follicular center cells do not have detectable bcl-2 protein. The bcl-2 gene is translocated in most conventional small cleaved follicular center cell (SCFCC) lymphomas (centroblastic/centrocytic) but not in centrocytic lymphomas (CC). The translocated gene in the SCFCC lymphomas leads to 'aberrant' bcl-2 expression by the neoplastic follicular center cells. The frequency with which the normal non-translocated gene is expressed in CC lymphomas is, however, not well documented. Paraffin sections from 22 cases of centrocytic lymphoma were therefore stained with an anti-bcl-2 antibody. Genotypic studies in 14 cases demonstrated bcl-1/PRAD1 (cyclin D1; CCND1) rearrangements in ten and bcl-2 rearrangements in none. All centrocytic lymphomas demonstrated bcl-2 protein expression in the majority of neoplastic cells. Negative staining residual follicular centers were identified in four cases emphasizing the mantle zone growth pattern of a subset of CC lymphomas. Expression of bcl-2 protein in the absence of bcl-2 gene rearrangement is a feature shared by centrocytic lymphomas and mantle zone cells. However, because this type of bcl-2 expression is not specific for B-cells of the mantle zone, it does not further elucidate the true cell of origin for the centrocytic lymphomas.

Gene Rearrangement↗

PubMed1999

Double esterase staining of the bone marrow contributes to lineage identification in a case of minimally differentiated acute myeloid leukaemia (AML M0).

Minimally differentiated acute myeloid leukaemia (AML-M0) may pose difficulty in diagnosis since morphological criteria alone are not reliable. Other studies such as electron microscopy, immunocytochemistry and surface marker analysis are needed. The role of cytochemistry has been limited to the negative staining of blasts for Sudan Black B and myeloperoxidase. An abnormal morphology and cytochemistry of bone marrow maturing cells may indicate the myeloid nature of acute leukaemia. In this case of AML-M0, increased numbers of maturing and mature bone marrow granulocytic cells staining simultaneously for both specific and non-specific esterase (double esterase) are described. In acute leukaemia, this abnormal cytochemical finding seems to be specific for myeloid leukaemia and may be used as supplementary evidence of myeloid differentiation of morphologically undifferentiated blasts in cases of AML-M0.

Acute Disease↗

PubMed1995

Effect of the C-terminal proline repeats on ordered packing of squid rhodopsin and its mobility in membranes.

Negative stain electron microscopy and saturation transfer electron spin resonance spectroscopy have been used to compare the lattice ordering and in-plane membrane mobility of full-length and C-terminally cleaved squid rhodopsin. The C-terminus of squid rhodopsin contains a negatively charged region followed by 9-10 repeats of a proline-rich sequence, not found in rhodopsins other than those of cephalopod invertebrates, but similar proline repeats are found in other, unrelated membrane proteins. We find that the proline repeats cluster the rhodopsins into small groups, interfering with two-dimensional crystallization and maintaining their mobility in the membrane.

Animals↗

PubMed1996

The loss of lectin reactivity from human endometrium is a feature of malignant change.

Changes in the cell surface glycoproteins were investigated in endometrial adenocarcinomas using eight biotin-labelled lectins (Con A, LCA, WGA, e-PHA, l-PHA, SBA, PNA, LTA) which select for the major classes of N-linked and O-linked oligosaccharides. The tissues studied were 14 normal endometria, 20 cases of simple hyperplasia and 30 endometrial adenocarcinomas. Sections were cut at 5 microns from formalin fixed paraffin embedded blocks and were stained with an avidin-peroxidase method. All normal and hyperplastic endometria contained the full range of expected saccharides (positive staining for Con A, LCA, WGA, SBA, PNA, LTA, e-PHA and l-PHA). By contrast, over half of the endometrial adenocarcinomas exhibited a loss of galactosamine (56.7%) and over a third of them failed to reveal galactose (36.7%) and fucose (30.0%) (negative staining for SBA, PNA and LTA, respectively). Interestingly, following neuraminidase treatment, galactose was identified in all adenocarcinomas studied, but the expression of galactosamine and fucose was unaffected. There was a discrete linear staining at the level of the basement membranes in a proportion of endometrial glands treated with e-PHA, l-PHA and LCA; this was continuous in normal and hyperplastic endometria, while it was fragmentary in endometrial adenocarcinomas. The loss of galactosamine reactivity from endometrial adenocarcinomas was significantly correlated with high grade differentiation, and also with the more frequent occurrence of a poor oestrogen (ER) and progesterone (PR) receptor status and with an unfavourable 5-year survival. No relationship was found between fucose reactivity and tumour differentiation, stage of disease, hormone receptor status or prognosis. It is concluded that galactosamine loss, together with reduced fucose expression, is a common feature of endometrial malignancy, and that galactosamine deficient tumours may reflect a more aggressive biological behaviour.

Adenocarcinoma↗

PubMed2002

Trichogerminoma: a rare cutaneous adnexal tumor with differentiation toward the hair germ epithelium.

In 1992, Sau and colleagues described 14 cases of a rare cutaneous adnexal tumor with differentiation toward the hair germ epithelium. All cases in their study displayed a unique constellation of histological features which allowed the authors to consider the neoplasm to be a distinct entity and to designate it as 'trichogerminoma' (TG). We present a case of an adnexal tumor identical to that described as TG and report the immunophenotypical features of this neoplasm for the first time. A biopsy from a 41-year-old man revealed a well-demarcated epithelial tumor composed of multiple lobules located in the deep dermis without connection to the overlying epidermis and surrounded by a fibrous pseudocapsule. The tumorous lobules were composed of uniform basophilic cells with vesicular nuclei, dispersed chromatin and prominent nucleoli showing no prominent peripheral palisading. Some of the lobules had the appearance of densely packed 'cell balls' with peripheral condensation of the tumor cells. The stroma showed a moderate number of fibroblasts and mast cells. Reticulum staining revealed fine reticulum fibers surrounding the tumor aggregates with accentuation of the 'cell balls'. Immunohistochemically, the tumor cells expressed AE1/AE3, CK5/8, CK5/6, CAM5.2 and stained negatively for CK20, CK7, calretinin, Lu-5 and Thomsen- Friedensreich antigen. There was no increase in the numbers of CK20-positive Merkel cells in the epidermis overlying the tumor; however, a few Merkel cells were scattered in some tumor lobules. In addition, we stained 6 trichoblastomas (TBs) and found a particular pattern of calretinin expression in this tumor which was not observed in our case of TG. We conclude that pathological features allow the delineation of TG as a distinct adnexal neoplasm. Histological differential diagnosis includes basal-cell carcinoma (pilar type), large nodular TB, trichoblastic fibroma, trichoepithelioma, tricholemmoma, pilomatricoma and matrical carcinoma.

Adult↗

PubMed2005

[Efficient isolation of chondrocytes from rabbit articular cartilage with three-step enzymatic digestion and observation of their biological characteristics during cultivation in vitro].

OBJECTIVE: To observe the effect of isolating the chondrocytes from articular cartilage with the method of three-step enzymatic digestion, and the biological characteristics of the isolated chondrocytes during cultivation in vitro in order to evaluate their biological activity. METHODS: The method of three-step enzymatic digestion was designed that the articular cartilage was digested one by one with the 1 g/L trypsin and 1 g/L EDTA, 1 g/L hyaluronidase and 2 g/L collagenase I in the culture medium to isolate chondrocytes. The harvesting and viability rate of the primary chondrocytes were detected. During the passage cultivation in vitro, the changes of the chondrocytes shape and growth were observed, the changes of the collagen type I and II and aggrecan in the extracellular matrix were investigated and detected. RESULTS: (1) The extracellular matrix of articular cartilage was completely dissolved by the three-step enzymatic digestion, and the chondrocytes were completely isolated from the solid matrix. The number of the harvested chondrocytes from every gram of wet cartilage was 50.3 x 10(6) on average, and their viability rate was 98.8% on average. (2) The primary and first passage chondrocytes had triangle or multi-angle shape, and became elliptic shape at the growing confluence with the positive immunohistochemical stain of collagen type II and the strong heterochromia to toluidine blue. The content of sulfate glycosaminoglycans (GAG) in the extracellular matrix of the primary passage cells was (92 +/- 10) microg/cm(2). The chondrocytes after the third passaging gradually became spindle shape with the negative stain of collagen type II and the weak heterochromia to toluidine blue. The content of sulfate GAG of the fourth passage cells was (48 +/- 12) microg/cm(2). CONCLUSION: (1) The method of three-step enzymatic digestion can make the extracellular matrix of articular cartilage completely degraded, and has advantages in the high efficiency of harvesting primary chondrocytes, high cellular viability rate and simple manipulation. (2) The primary and first passage chondrocytes have fine biological activity, and the chondrocytes after the third passaging have lost their special biological activity.

Animals↗

PubMed1979

Ultrastructure of Legionella pneumophila.

Eleven lung samples positive for Legionnaires' disease, 12 strains of Legionella pneumophila cultured on various bacteriological media, and one strain growth in the yolk sac of fertile hens' eggs were examined by negative staining, thin sectioning, and scanning electron microscopy. All organisms studied were ultrastructurally similar irrespective of strain, source, or method of cultivation, presenting mainly as short rods, 0.6 x 1.5 micrometer, with tapered ends, though long forms and filaments were also evident. In this they resembled typical Gram-negative organisms. Division was by non-septate binary fission, and the cell wall was composed of two triple-unit membranes with morphological evidence of a peptidoglycan layer. The bacterial cytoplasm was rich in ribosomes and nuclear elements and often contained vacuoles. No acid polysaccharides or bacterial appendages were detected surrounding the organisms. In lung tissue and yolk sac membranes, the organisms replicated within the cytoplasm of infected cells and in the intercellular spaces and were specifically identified in thin sections by immunoferritin techniques.

Bacteria↗