Histology and histopathology Vol.12, nº 2 (1997)

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Open Access
Growth factors and remyelination in the CNS
(Murcia : F. Hernández, 1997) Woodruff, R.H.; Franklin, R.J.M.
It is now well established that there is an inherent capacity within the central nervous system (CNS) to remyelinate areas of white matter that have undergone demyelination. However this repair process is not universally consistent or sustained, and persistent demyelination occurs in a number of situations, most notably in the chronic multiple sclerosis (MS) plaque. Thus there is a need to investigate ways in which myelin deficits within the CNS rnay be restored. One approach to this problem is to investigate ways in which the inherent remyelinating capacity of the CNS rnay be stimulated to remyelinate areas of long-term demyelination. The expression of growth factors, which are known to be involved in developmental myelinogenesis, in areas of demyelination strongly suggests that they are involved in spontaneous remyelination. Therefore delivery of exogenous growth factors into areas of persistent demyelination is a potential therapeutic strategy for stimulating remyelination. This review will discuss the evidence that growth factors rnay have a role in promoting CNS remyelination by enhancing the survival and stimulating the proliferation and recruitment of remyelinating oligodendrocytes.
Open Access
Gastric mucosal injury and repair, effect of aging
(Murcia : F. Hernández, 1997) Majumdar, A.P.N.; Fligiel, S.E.G.; Jaszewski, R.
Although the gastric mucosa of healthy adult animals possesses the inherent capacity to promptly repair (often within 24 h) after a minor to moderate injury, aging appears to diminish its reparative capacity. At least two different repair mechanisms are thought to participate in full repair of the damaged gastric mucosa: the initial rapid process of mucosal restitution begins by migration of viable epithelial cells from gastric pits and glands; the subsequent slower process is replacement of lost cells by cell division. Intracellular events that regulate these processes are poorly understood, nor do we know how they may be affected by aging. However, evidence is accumulating which suggests that a number of gastrointestinal hormones/growth factors, most notably EGF and TGF-a may play a critica1 role in regulating gastric mucosal reparative processes. Since EGF and TGF-a exert their physiological actions by activating the intrinsic tyrosine kinase (Tyr-k) activity of their common receptor, the EGF-R, studies have been performed to assess the role of EGF-R Tyr-k in regulating mucosal reparative processes during aging. Recent data suggest that the age-related decline in mucosal repair after acute injury could in part be due to decreased activation of EGF-R Tyr-k. In addition, polyamines and prostaglandins are also thought to be involved in gastric mucosal reparative processes. Although the involvement of polyamines in gastric mucosal reparative processes during aging has not yet been studied, decreased mucosal prostaglandin levels in the aged are thought to be a causative factor for the increased susceptibility of the mucosa to injury. These and other relevant matters are discussed in the current review.
Open Access
Distribution and pathophysiologic role of molybdenum-containing enzymes
(Murcia : F. Hernández, 1997) Morikawa, Y.; Yamamoto, T.; Higashino, K.
The importance of molybdenum-containing enzymes in the pathophysiology of a number of clinical disorders necessitates a comprehensive understanding of their histological localization and expression. The objectives of this review are to cover such enzymes so far reported and their enzyme- and immunohistochemical localization in various tissues and species, and to discuss their possible pathophysiological effects. The molybdenum cofactor is essential for the activity of the three molybdenum-containing enzymes, sulfite oxidase, xanthine oxidase and aldehyde oxidase. Sulfite oxidase serves as the terminal enzyme in the pathway of the oxidative degradation of sulfur amino acids, and is also involved in preventing the toxic effects of sulfur dioxide. Biochemical study has revealed a high activity of sulfite oxidase mainly in the liver, heart and kidney with lesser activity observed in other tissues. Subcellular observations have shown that this enzyme is present in the mitochondrial intermembraneous spaces. Xanthine oxidase is the final enzyme in the conversion of hypoxanthine to xanthine, and subsequently, to uric acid. Unlike sulfite and aldehyde oxidases, xanthine oxidase can be converted to xanthine dehydrogenase, and vice versa. Xanthine oxidase has been widely investigated for its role in post-ischemic reperfusion tissue injury. Enzyme- and immunohistochernical studies of its localization in various animal species and tissues have shown its ubiquitous distribution in the liver, small and large intestine, lung and kidney, and other tissues. Aldehyde oxidase shares a similar substrate specificity with xanthine oxidase. Although the tissue localization of this enzyme has not been studied as thoroughly as that of xanthine oxidase, aldehyde oxidase is reportedly found in the digestive gland of terrestrial gastropods, the antennae of certain moths as well as the mammalian liver. Recently, the ubiquitous distribution of aldehyde oxidase has been demonstrated in rat tissues. The aldehyde oxidase activity of herbivores exceeds that of carnivores, suggesting a possible role of this enzyme as a Offprint requests to: Dr. Yuji Moriwaki, M.D., Third Department of lnternal Medicine, Hyogo College of Medicine, Mukogawa-cho 1-1, Nishinomiya, Hyogo 663, Japan protection against the effects of toxic plants. The relationship between the tissue localization of these enzymes and their pathophysiological roles is reviewed.
Open Access
Collagen types Vlll and X, two non-fibrillar, short-chain collagens. Structure homologies, functions and involvement in pathology
(Murcia : F. Hernández, 1997) Sutmulle, M.; Bruijn, J.A.; De Heer, E.
. Collagens can be divided into two groups, Le., fibrillar and non-fibrillar collagens. Short-chain collagens, a subgroup of non-fibrillar collagens, comprises collagen type VI11 and type X. These two collagen types show severa1 similarities in stnicture and possibly also in function. Type VI11 collagen appears to be secreted by rapidly proliferating cells. It can be found in basement membranes and may serve as a molecular bridge between different types of matrix molecules. In different tissues this collagen type may serve different functions. Stabilization of membranes, angiogenesis, and interactions with other extracellular matrix molecules. Since collagen type X is produced by hypertrophic chondrocytes, this collagen type can only be found in matrix of the hypertrophic zone of the epiphyseal growth plate cartilage. Collagen type X is probably involved in the process of mineralization, endochondral ossification, and is also proposed to play a role in angiogenesis. Collagen types VI1 and X may be involved in matrix and bone disorders. Their structure, function, and involvement in pathology are discussed in this review.
Open Access
Endotheliitis-like changes in chronic hepatitis C
(Murcia : F. Hernández, 1997) Lory, J.; Zimmermann, Astrid
Liver biopsies in hepatitis C frequently show bile duct damage, lymphoid follicles, large and small droplet fat, hepatocyte multinucleation. Mallory bodylike material, and activation of sinusoidal inflammatory cells. Even though these lesions are useful parameters in the diagnosis of hepatitis C, their specificity remains uncertain. Endotheliitis-like changes of small portal veins have been described for various liver diseases, including viral hepatitis. The aim of the present study was to investigate the prevalence and severity of endotheliitis-like changes in chronic hepatitis C in comparison with chronic hepatitis B. For this purpose, liver biopsies of 50 patients with chronic hepatitis C and 48 patients which chronic hepatitis B were systematically analyzed for the presence of endotheliitis-like changes. Endotheliitis-like changes were defined as lymphocytic infiltration of venous walls, subendothelial lymphocyte accumulation, adherence of lymphocytes to the endothelium, and endothelial cell damage. Endotheliitis-like change severity was graded (borderline/questionable; slight to moderate; severe), and endotheliitis-like changes were analyzed in small portal veins and in central veins. Endotheliitis-like changes were significantly more frequent in chronic hepatitis C than in chronic hepatitis B (41.5% vs. 6.9%; ~ 0 . 0 5 ) . In chronic hepatitis C, endotheliitis-like changes predominated in small portal veins, but 27% of small hepatic veins were involved as well. The findings indicate that endotheliitis-like changes may represent a useful histological parameter in the diagnosis of chronic hepatitis C.
Open Access
Comparative stereological studies on zonation and cellular composition of adrenal glands of normal and anencephalic human fetuses. II. Cellular composition of the gland
(Murcia : F. Hernández, 1997) Bocian-Sobkowska, J.; Malendowicz, L.K.; Woíniak, W.
In our previous paper (Bocian-Sobkowska et al., 1997) we demonstrated a striking difference in development of zonation in adrenals of normal and anencephalic human fetuses. The purpose of the present study was to characterize, by means of stereology, the cellular composition of developing adrenals in the same case. Studies were performed on 11 pairs of adrenal glands from normal fetuses and 10 from anencephalic fetuses. In the studied period of development (24 to 39 weeks of intra-uterine life) the average volume of cells in normal glands increased as follows: zona glomerulosa (ZG) from 355 to 870 pm3; zona fasciculata (ZF) from 779 to 1200 pm3; fetal zone (FZ) from 2004 to 2380 pm3; and medulla (M) from 600 to 970 ym3. In anencephalic fetuses, the appropriate values were: ZG - 380-680 pn3; ZF - 460-680 pm3; FZ - 1820-1680 pm3; and M - 870-1400 pm3. At the end of the studied period the number of ZG cells in normal fetuses was two fold higher than in anencephalics, ZF cells - 6-fold and in FZ - 5-fold higher, while in the M the number of cells was nearly equal in both groups. During the whole investigated period of intra-uterine development the total number of adrenocortical cells in normal glands increased ca 2.5-fold, while in anencephalic glands only ca 0.5-fold, reaching at the end ca 40% of normal value. In both normal and anencephalic adrenals the number of ZG and M cells was highly correlated with ZG/M cell ratio, being slightly higher in normal glands. No such relation was demonstrated for cells of the remaining adrenocortical zones.
Open Access
Estimation and comparison of the contents of blood group B antigens in selected human tissues by microphotometric quantification of Griffonia simplicifolia agglutinin 1-B, staining with or without prior a-galactosidase digestion
(Murcia : F. Hernández, 1997) Ito, N.; Nagaike, C.; Morimura, Y.; Hatake, K.
Griffonia simplicifolia agglutinin 1-B4 (GSAI-B4) has broader specificity for B antigen variants and can recognize the antigens in a wide variety of human tissues. Thus, the concentration range of GSAIB4 required for staining and the susceptibility of staining to a-galactosidase digestion is presumed to correlate well with the density of B antigens in tissue sections. By microphotometric quantification of staining intensity at different concentrations of GSAI-B4 with or without agalactosidase digestion, concentration of B antigens in selected tissues was evaluated and compared. Based on the present results and the previous ones of direct measurement of galactose of B antigens in sublingual glands and red blood cells (Ito et al., 1993), the order of concentration of B antigens in tissues examined was estimated as follows; mucous cells of sublingual glands from German nonsecretors < red blood cells and vascular endothelial cells (=2.7x10-3nmole/cm2), thyroid papillary carcinomas and Hassall's corpuscles from nonsecretors < mucous cells of sublingual gland from Japanese nonsecretors < pancreatic acinar cells from both secretor and nonsecretors, Hassall's corpuscles and kidney collecting tubules form secretors < mucous cells of sublingual gland from secretors (>8.5-11.7 nmole/cm2) and mucous cells of Brunner 'S gland from nonsecretors < mucous cells of Brunner's gland from secretors. From the above estimation, it is apparent that the expression of B antigen in Brumer's gland is partly dependent on the secretor status of individuals and that Japanese nonsecretors secrete substantial amounts of B antigens from sublingual gland while German nonsecretors do not. The present results also revealed an unexpected staining behavior of GSAI-B4 in some tissues, i.e. in mucous cells of sublingual glands and collecting tubules of kidney from secretors, staining olrprint reguests to: Nobuaki Ito, Ph.D., Department of Legal Medicine, Nara Medical University, Kashihara Nara 834, Japan intensity was markedly depressed at higher concentration of the lectin and this depression was recovered by prior a-galactosidase digestion. In addition, the present method was successfully applied for the estimation of the content of B antigens neoexpressed in thyroid papillary carcinomas, showing that the content of B antigen had a similar leve1 to that of red blood cells and vascular endothelial cells.
Open Access
The microanatomy of calcium stores in human neutrophils, Relationship of structure to function
(Murcia : F. Hernández, 1997) Pettit, E.J.; Davies, E.V.; Hallett, M.B.
As changes in cytosoiic free ca2+ play key roles in coupling responses in neutrophils, it is important to locate and identify ca2+ storage sites within these cells. Here, recent data is presented which highlights the functional link between rnicroanatomical structure and cell signailing function. Fluorescent opticai probes for cytosolic free ca2+ have been used, together with organelle specific markers. We present evidence from conventional fluorescence microscopy, together with ratiometric and confocal laser scanning fluorescence microscopy, which pin-points two celiular locations for ca2+ within the neutrophil; one within the nuclear lobes, and the other towards the ceii periphery. Knowledge of these two locations provides a clear insight into how signailing in this cell type is regulated and provides a framework for explaining how specific stimuli act to produce specific responses.
Open Access
Ultrastructure of atheromatous lesions experimentally induced in Syrian hamsters of the APA strain
(Murcia : F. Hernández, 1997) Yamanouchi, J.; Sugawara, Y.; Itagaki, S.; Doi, K.
In order to examine whether diabetes enhances primary aortic lesions up to atherosclerotic ones, mild primary lesions were induced in aorta of APA hamsters by an administration of vitamin D2 (VD) andlor stop-and-reflow (SR)-operation, a modification of renal artery clamping. At 2 months after the treatment with the combination of VD-administration and SRoperation, atheromatous lesions, characterized by an appearance of many foam cells in the intima, were observed in the abdominal aorta, the site of SRoperation, in streptozotocin (SZ)-induced diabetic APA hamsters. Foam cells in the atheromatous lesions were originated from smooth muscle cells and monocytel macrophages. On the other hand, neither VDadministration alone nor SR-operation done developed atheromatous lesions in SZ-induced diabetic APA hamsters. In conclusion, we succeeded in a rapid induction of atherosclerotic lesions in abdominal aorta of SZ-induced diabetic APA hamsters by the combination of VD-administration and SR-operation.
Open Access
Membrane skeletons in avian erythrocytes as revealed by the quick-freezing and deep-etching method
(Murcia : F. Hernández, 1997) Terada, N.; Fuji, Y.; Kitano, K.; Ohno, S.
Ultrastructure of chicken erythrocytes were examined by the quick-freezing and deep-etching (QFDE) method. Some erythrocytes were fixed with paraformaldehyde and prepared with erythrocytesplitting method or saponin treatment to remove soluble proteins before quick-freezing. Others were prepared in the cytosol buffer with the erythrocyte-splitting method to obtain natural state of cytoskeletons. Non-expanding membrane skeletons were highly condensed on the cytoplasmic side of lipid membrane in the paraformaldehyde- fixed specimens. Under unilateral extension of the specimens, long stretched filaments were connected alternately with condensed filamentous or granular structures under erythrocyte membranes. As the membrane skeletons got closer to the marginal bands, they become more dense network structures. Moreover, in the fresh unfixed specimens, dense networks of filaments were localized underlying erythrocyte membranes in a relatively intact state. Fine filaments connected the marginal microtubule bands to the cytoplasmic sides of erythrocyte membranes. The different distribution of each cytoskeletal component and the association of these structures may support the elliptocytic shape of chicken erythrocytes and resist the dynamic circumstance.
Open Access
lmmunocytochemical correlates of an extrapituitary adrenocortical regulation in man
(Murcia : F. Hernández, 1997) Heym, C.
Investigations reviewed in this article provide cytochemical and functional support for a significant involvement of extrapituitary factors in human adrenocortical functions. Among these factors neural messengers may play a crucial role in the adrenocortical regulation, arising from specifically coded postganglionic neurons with both, extrinsic and intrinsic locations, as well as from chemically characteristic afferent neurons. The close association of varicose transmitter segments with steroid hormone synthesizing cells and their occurrence at arteries and sinusoid capillaries are indicative for both direct and indirect regulatory mechanisms on cortical functions. The immunohistochemical presence of neuropeptides and cytokines in endocrine andlor immune cells of the human adrenal medulla and cortex as well as specific binding sites on steroidogenic cells indicate the modulatory implication of additional short-paracrine-and ultrashort-autocrine-feedback loops on cortical cell proliferation and steroid metabolism. The summarized data suggest that basa1 endocrine influence of the hypothalamo-pituitary axis on adrenocortical growth and functions in man is controlled by the nervous system that also regulates local fine-tuning of human cortical activity.
Open Access
Hepatocyte apoptosis in hepatic iron overload diseases
(Murcia : F. Hernández, 1997) Zhao, M.; Laissue, J.A.; Zimmermann, Astrid
In this retrospective study, we systematically analyzed hepatocyte apoptosis in three situations of hepatic iron overload (hereditary hemochromatosis; hepatic iron overload of unknown reason; iron overload due to hyperhemolysis or exogenous iron administration). Apoptosis was assessed by use of DNA nick end-labelling. The results suggest that hepatic iron overload is associated with an increased apoptotic rate of hepatocytes, and that iron-laden hepatocytes in hemochromatosis behave, with respect to apoptosis, differently from those in other states of iron overload. The hepatocyte apoptotic rate tended to increase as a function of the degree of iron storage. As in other pathological liver changes studied so far, an elevated apoptotic rate of hepatocytes predominated in the pericentral parts of liver acini in hemochromatosis, but not in the two other groups of hepatic iron overload. Possible mechanisms for this difference are discussed, particularly with respect to a participation of the Kupffer cell system.
Open Access
The alveolar type II cell is a pluripotential stem cell in the genesis of human adenocarcinomas and squamous cell carcinomas
(Murcia : F. Hernández, 1997) Ten Have-pbroek, A.A.W.; Benfield, J.R.; Van Krieken, J.H.J.M.; Dijkman, J.H.
Studies in a canine bronchogenic carcinoma model indicate that alveolar type 11 cells may differentiate from carcinogen-exposed epithelium of larger bronchi and generate adenocarcinomas with bronchioloalveolar and other growth patterns. In this study, we investigated whether type 11 cells are one of the major proliferating cells (=stem cells) in the genesis of two major subsets of bronchogenic carcinoma in humans. Adenocarcinomas (17 bronchioloalveolar; 3 papillary; and 10 other) and squamous cell carcinomas (n=27) as well as (pre)neoplastic lesions in adjacent bronchi and bronchioles were examined for the presence of type 11 cell markers and cellular proliferation markers (PCNA; Ki-67) using light and electron microscopy and immunohistochemistry. Distinctive features of type 11 cells, which do not depend upon the degree of cell maturity, are the approximately cuboid shape, large and roundish nucleus, cytoplasmic staining for surfactant protein A (SP-A), and presence of multilamellar bodies or their precursory forms. Cells with this phenotype were found in early progressive (i.e., dysplastic, in situ, microinvasive) lesions in conducting airways and in al1 the carcinomas investigated, although with a much greater abundance among glandular lesions compared to squamous lesions. The most consistent sites of type 11 cells were the basal and adjacent epithelial layers. Nuclear PCNA (Ki-67) expression usually predominated in the same region. None of the lesions displayed specific Clara cell features. Our findings strongly suggest that the type 11 cell is a pluripotential stem cell in human lung carcinogenesis. Based on our findings in humans and dogs, we postulate that type 11 tumor stem cells may originate from one of two sources: (1) normal bronchial epithelium (by an oncofetal mechanism of differentiation); and (2) normal alveolar type 11 cells.
Open Access
Comparative stereological study on zonation and cellular composition of adrenal glands of normal and anencephalic human fetuses. l. Zonation of the gland
(Murcia : F. Hernández, 1997) Bocian-Sobkowska, J.; Malendowicz, L.K.; Woíniak, W.
Comparative stereological studies were performed on zonation of adrenal glands in 10 anencephalic and 11 normal fetuses, aged between 24 and 39 postovulatory weeks. The development of adrenal fetal zone (FZ) is the main factor responsible for normal adrenal gland growth during the intra-uterine life. At the end of fetal '3e riod volume of this zone attains over 8200 mm and constitutes 69-70% of the total gland volume, while respective values for zona glomerulosa (ZG), zona fasciculata (ZF) and medulla IM' are 1665 mm3 (14%) 833 mm3 (7%) and 1071 mm (9%). These data were in striking contrast with those found in adrenals of anencephalic fetuses, in which volume of the gland attained only ca 35% of that in normal fetuses. In the oldest anencephalic fetus studied (39 weeks) the volume of the fetal zone was 962 mm3 (ca 8-folds lower than in normal fetus) comprising only 25% of the total gland volume. For the remaining zones the values were: ZG - 1501 mm3 (ca 90% of the normal value and 39% of the total gland volume); ZF - 770 mm3 (ca 92% and 20% respectively), and M - 539 mm3 (ca 50% and 14%, respective1 y). This stereological study provides the first systemic description of the development of adrenal gland of anencephalic fetuses in comparison with the normally developing gland. Moreover, evidence is given that the growth of adrenal medulla is also retarded in anencephaly while the growth of the zona glomerulosa remains rather unaffected.
Open Access
Neuropeptides in the seminal vesicles, locations, binding sites and functional implications
(Murcia : F. Hernández, 1997) Pinho, M.S.; Afonso, F.; Rodriguez, G.; Gulbenkian, S.; Mata, L.R.
The importance of neurona1 factors in the normal physiology of the seminal vesicles has been traditionally underestimated when compared to the trophic role of androgens. Immunohistochemical, autoradiographical and pharmacological experiments have, however, raised the possibility that neuropeptides, such as vasoactive intestinal polypeptide (VIP), neuropeptide tyrosine (NPY) and calcitonin gene-related peptide (CGRP), are necessary for full seminal vesicle function and development. These neuropeptides may be involved in the regulation of secretion, smooth muscle tone and blood flow. Furthermore, neuropeptides may have functional interactions with androgens affecting, probably, androgen receptordependent gene expression in these glands. It is now timely to focus attention on the biological relevance of neuropeptides in the seminal vesicles.
Open Access
Ultrastructural changes in the synthetic and secretory patterns of pulmonary surfactant following pilocarpine in vivo
(Murcia : F. Hernández, 1997) Smith, Dennis M.; Sommers Smith, Sally K.
Previous studies have demonstrated that the muscarinic agonist pilocarpine stimulates the secretion of pulmonary surfactant from mammalian alveolar type 11 cells. The results of the present study quantify, via ultrastructural stereologic analysis, this response through 24 hours. The cytoplasmic volume density of lamellar bodies decreases significantly at 0.5 and 4 hours postinjection. This value is increased significantly at 12 hours post-injection. Elements of the secretory apparatus increase significantly at many of the post-injection times. At 12 hours post-injection many of the type 11 cells are quite laden with lamellar bodies, with some appearing surprisingly large. This may be a useful model for continued study of the relationship between synthesis and secretion of pulmonary surfactant.
Open Access
Antioxidant enzyme levels in cancer
(Murcia : F. Hernández, 1997) Oberley, T.D.; Oberley, L.W.
Normal cells are protected by antioxidant enzymes from the toxic effects of high concentrations of reactive oxygen species generated during cellular metabolism. Even though cancer cells generate reactive oxygen species, it has been demonstrated biochemically that antioxidant enzyme levels are low in most animal and human cancers. However, a few cancer types have been found to have elevated levels of antioxidant enzymes, particularly manganese superoxide dismutase. Morphologic studies of animal and human cancer have confirmed that although the majority of tumor cell types from severa1 organ systems have low antioxidant enzymes, adenocarcinomas may have elevated manganese superoxide dismutase and catalase levels. However, al1 cancers examined to date have some imbalance in antioxidant enzyme levels compared with the cell of origin. Antioxidant enzyme importance in cancer genesis has been difficult to evaluate in early cancerous lesions using biochemical techniques because such lesions are small and therefore below the leve1 of detection. Using immunohistochemical techniques, early lesions of human and animal cancers were demonstrated to have low antioxidant enzymes, thus suggesting a role for these enzymes both in the genesis of cancer and the malignant phenotype. Al1 but one human cancer cell type (the granular cell variant of human renal adenocarcinoma) examined showed both low catalase and glutathione peroxidase levels, suggesting that most cancer cell types cannot detoxify hydrogen peroxide. Our results to date are used to propose new cancer therapies based on modulation of cellular redox state.
Open Access
55-Azacytidine (5Az) inducesapoptosis in PC12 cells: a model for 5Az-induced apoptosis in developing neuronal cells
(Murcia : F. Hernández, 1997) Hossain, M.M.; Nakayama, Hiroyuki; Takashima, A.; Goto, N.; Doi, K.
Our previous in vivo and in vitro studies showed that 5-azacytidine (5Az), a cytidine analog, induced apoptosis in developing neuronal cells in mice. To develop a system in which the precise molecular mechanism of 5Az-induced apoptosis in developing neuronal cells could be elucidated, we carried out the present study with PC12 cells. These cells are derived from a rat pheochromocytoma and extrude neurites in response to nerve growth factor (NGF). Light microscopy showed dose-dependent pyknotic and karyorrhectic changes in undifferentiated PC12 cells. Although they were less sensitive to 5Az, NGF-treated differentiated cells showed the same changes. Analysis by the TUNEL method (an in situ method for the detection of apoptosis) showed positive signals in the pyknotic and fragmented nuclei of these cells. Transmission electron microscopy revealed margination, segmentation, and condensation of nuclear chromatin, cell body shrinkage, and cytoplasmic vacuolization. Scanning electron microscopy demonstrated bleb formation on the cell surface. These pathomorphological changes are typical of apoptosis. 5Az seemed to affect cells that were in the proliferative stage; when the cells were terminally differentiated, their sensitivity to 5Az appeared to decline. PC12 cells could be used as a pathomorphological and biochemical model for studies of 5Az-induced neuronal cell apoptosis at the molecular and genetic level.
Open Access
The skin injury induced by high energy dose of ultraviolet in hairless descendants of Mexican hairless dogs
(Murcia : F. Hernández, 1997) Ishii, Y.; Kimura, T.; Itagaki, S.; Doi, K.
Histopathological changes in the dorsal skin of hairless descendants of Mexican hairless dogs (MHDs) exposed to artificial irradiation with high energy dose ( 1 8 0 k ~ l m ~of) ultraviolet (UV) rays (UVA+B) were investigated. Macroscopically, erythema and edema were observed in the irradiated skin at 1 day after irradiation (DAI), and blister formation occurred except one dog at 2 DAI. Erythema almost disappeared at 5 DAI, and at 6 DAI, the skin recovered to almost normal state. Light microscopically, sunburn cells were observed at 1 DAI. Then intercellular edema and blister formation in the epidermis and dermal edema were evident at 2 and 3 DAI. At 6 DAI, the skin showed almost normal features except for slight epidermal thickening, but melanin granules, which were distributed in almost the whole length of the epidermis before UV irradiation, were detected only in cells which seemed to be melanocytes except one dog. Dihydroxyphenylalanine (D0PA)- positive melanocytes almost disappeared at 1 and 2 DAI, and at 6 DAI, the number of DOPA-positive melanocytes increased over the leve1 before UV irradiation. The ultrastructural features of melanocytes were characterized by vacuolated cytoplasm, decreased melanosomes, irregular-shaped nuclei and shortened dendrites at 1 DAI, and returned to normal at 6 DAI. These findings of melanocytes reflect the severity of the skin injury and support weak suntan reaction in this case. In conclusion, severe form of UV-induced skin injury seen in humans could be reproduced in hairless descendants of MHDs exposed to high energy dose of artificial UVA+B.
Open Access
Ultrastructural alterations of the cortical epithelial cells of the rat thymus after cyclophosphamide treatment
(Murcia : F. Hernández, 1997) Yoon, S.; Yoo, Y.H.; Kim, B.S.; Kim, J.J.
A single dose of cyclophosphamide (CY) was administered to Sprague-Dawley rats to investigate the effects of CY on thymic cortical epithelial cells (TCE) at the ultrastructural level. The most striking finding among the alterations in the TCE after CY treatment was a cytoplasmic vacuolization with an increased amount of granular and membranous content. The granular content appeared not only as dense bodies but also as loosely aggregated forms or finely dispersed grandes. The membranous structures appeared in various forms including vesicular, tubular, vacuolar and irregular membranous structures and myelin figures. Some of the membranous structures contained granular material. Severa1 vacuoles were closely associated with the endoplasmic reticulum (ER). The morphological alterations of the ER were also remarkable. The Golgi apparatus, mitochondria and vesicles increased in number. The cytoplasm became densely granulated due to an increased number of ribosomes and an increased amount of granular material. The tonofilaments lost their original array and increased in amount. The cell surface exhibited many cytoplasmic processes like microvilli. It seems that the above features result not only from some damage by CY, but are also signs of a hyperfunctiona1 state of the TCE, probably due to their important functions in repopulation and maturation of the cortical thymocytes during recovery after CY-induced acute thymic involution, including the secretion of some humoral factors.