Histology and histopathology Vol.11, nº 2 (1996)

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Open Access
Heterogeneous ulmtrastrucmtuorf em elanosome formation in the goldfish induced by osmotic stress
(Murcia : F. Hernández, 1996) Schraerrneyer, U.; Dohms, M.; Rack, M.
In this study, melanophore cytodifferentiation in the fins of xanthic goldfish that had been exposed to osmotic stress for 18 days was investigated. It was found that multi-vesicular bodies (MVB) are not the only type of premelanosome. Granules having a homogeneous matrix also function as premelanosomes. The presence of acid phosphatase reaction product inside the melanin granules indicated that these organelles in this animal were also related to lysosomes. DOPA-oxidase of tyrosinase, the key enzyme in melanogenesis, was surprisingly not only detected in melanocytes but also in the Golgi stacks of dermal cells. Due to the mechanisms of premelanosome formation it is evident that cytoplasmic material also serves as substrate for melanogenesis. EDX microanalysis was performed to measure the ionic composition of the melanin granules. After aldehyde fixation the newly-formed melanin granules did not contain Na, but had accumulated Ca.
Open Access
Expression of cytoskeletal proteins and ATPase activity in bovine femoral artery and vein intima
(Murcia : F. Hernández, 1996) Trosheva, M.; Dikranian, K.; Nikolov, Sp.
Intima1 cells play an important role in the biology of the vascular wall. Variability in the metabolic activity of intimal smooth muscle cells (SMC), as well as the differential expression of cellular cytoskeletal proteins depend on factors such as degree of differentiation, aging, atherosclerosis, etc. Myosin ATPase activity and cytoskeletal proteins were studied in the intima of bovine femoral arteries and veins of mature animals. In some arteries the intima was thickened and two distinct layers - inner elastic hyperplastic (EHL) and outer, musculo-elastic (MEL) were observed. ATPase activity was well defined in endothelial cells (EC) as well as in SMC. However, differential enzymatic expression was observed in thickened intimas. SMC in the EHL were ATPase negative, while in the MEL they were ATPase positive. Al1 EC and SMC in the «normal» intimas were vimentin positive, desmin and cytokeratin negative. In vessels with thickened intimas, the EHL showed intensive vimentin positivity; in the MEL desmin immunoreactive SMC were numerous as were as those in the media. Vimentin-positive SMC occupied their innermost part. Differences in the expression of ATPase activity and cytoskeletal proteins is discussed in terms of possible migration of media1 SMC andlor morphological modulation observed in vessels with altered vascular walls.
Open Access
Use of lectin-probes for correlative histochemical and biochemical assessments of the glycosylation patterns of secretory proteins, including kallikreins, in salivary glands and saliva
(Murcia : F. Hernández, 1996) Garrett, J.R.; Proctor, G.B.; Zhang, X.S.; Shori, D.K.; Schulte, B.A.
Labelled lectins were used as probes to study the glycosylation and secretion of submandibular glycoproteins not only in sections of fixed glands but also in glandular extracts and in nerve-induced saliva, after electrophoretic separations and immobilization in nitrocellulose membranes. In cats the glycoproteins in sympathetic saliva differed considerably from those in parasympathetic saliva. In sympathetic saliva they were found to originate mainly from striated ducts, to some extent from demilunar cells and to a small extent from acinar cells, whereas in parasympathetic saliva they arose mainly from acinar-cells añd demilunes and only to a small extent from striated ducts. In rat submandibular glands sympathetic stimulation caused extensive depletion of lectin stainable granules from granular tubules. Corresponding strong binding occurred with the same lectins to constituents in saliva that ran between 25 and 35 kD on SDS gel electrophoresis and were shown to contain tissue kallikreins. Their binding patterns suggested that individual kallikreins from the same gland may be glycosylated in different ways. This possibility was tested on five different kallikreins after separation from submandibular extracts by isoelectric focussing. Lectin bindings on slot blot preparations of these kallikreins were tested before and after N-glycosidase F, sialidase or endo-a-Nacetylgalactosaminidase digestions. Results showed that, despite their close genetic and structural similarities, the kallikreins are in fact differently sialylated and fucosylated and the novel finding that some contain Oglycosidically linked side chains as well as the anticipated N-glycosidically linked side chains was revealed. Thus, correlative histochemical and biochemical Offprint requests to: Professor J.R. Garrett, Secretory and Soft Tissue Research Unit, Department of Oral Pathology, The Rayne Institute, KCSMD, 123 Coldharbour Lane, London, SE5 9NU, England assessments of bindings with lectin probes has provided important new information about differences in the glycosylation pattems of individual glycoproteins stored within the same secretory granules.
Open Access
The intracellular origin of the melanosome in pigment cells. A review of ultrastructural data
(Murcia : F. Hernández, 1996) Schraerrneyer, U.
This paper is a review about the ultrastructural data dealing with the origin of the melanin granules in retina1 pigment epithelial cells, in melanocytes, in the ink gland of cuttle fish, in Kupffer cells of the liver, in neurona1 tissues, in cultured pigment cells. The role and structure of lysosomes in melanogenesis are discussed in a separate chapter. The early steps of melanogenesis are ultrastructurally very heterogeneous, even in the same cell types. With respect to this heterogeneity and the considerably different views on melanosome origin in the literature, the author hypothesizes that pigment cells may use protein matrices originated from different cellular pathways. 1) They may either produce a specific protein matrix and be converted into melanin in the classical way, or 2) altematively, a matrix resulting from lysosomal protein degradation or endocytotic pathways may be used and converted into melanin, as found in fibroblasts transfected with the tyrosinase gen or in Kupffer cells. The very heterogeneous ultrastructure of the polymerizing melanin may be influenced by the amount and sterical availability of tyrosine residues in the protein moieties and the activity of tyrosinase.
Open Access
Ultrastructural studies on myofibrillogenesis and neogenesis of skeletal muscles after prolonged traction in rabbits
(Murcia : F. Hernández, 1996) Sun, J.S.; Hou, S.M.; Hang, Y. S.; Liu, T,K.; Lu, K.S.
Little is known about the morphological response of muscle after long term traction. The purpose of this study was to investigate the morphological changes of skeletal muscle during limb lengthening. After application of mini-extraskeletal fixator, the hindlimb of New Zealand white rabbit was osteotomized and then slowly lengthened at the rate of 1 mmlday up to a 20 mm gain in length. The muscles of hindlimbs were perfused and dissected. Morphological studies were performed at electron microscopic level. Transmission electron microscopy revealed foci of microtrauma at the myotendinous junction. The distance between the muscle fibers and tendon parenchyma increased, with numerous primitive mesenchyme-like cells interposed within this gap. The cytoplasmic space of these cells was devoid of myofibril formation at the ends of stretched fibers. Within the satellite near the myotendinous junction myofilament production was observed in various gradations of maturation. It is concluded that myofibrillogenesis with traction neogenesis of skeletal muscle during limb lengthening does exist and occurs mainly near the myotendinous junction. The myotendinous junction in mature skeletal muscle actively participated in the process of limb lengthening.
Open Access
A change in the localization of the region trapping immune complexes in rat popliteal lymph nodes during development of germinal centers, with regard to the distribution of follicular dendritic cells
(Murcia : F. Hernández, 1996) Sato, H.; Dobashi, Michio; Maeda, K.
A study was conducted to clarify changes in the relationship between the region of irnrnune complex (IC) trapping by follicular dendritic cells (FDCs) and the distribution of FDC during reaction of germinal centers (GCs), and to examine the relationship between the tridiniensional shape of the IC-trapping regions and their two-dimensional shape. Five-week-old rats were given footpad injections of sheep red blood cells, and then their popliteal lymph nodes were excised between days O and 42, 24 h after injection of peroxidase-antiperoxidase complex (PAP) as an IC. The specimens were immunostained for PAP trapping on serial paraffin sections, and for S-100 protein as a marker of FDCs. It was found that during the GC reaction, PAP trapping became weak and then disappeared on the basal side of developing GCs where S-100 protein-positive FDCs were still present. Al1 of the 1933 lymph follicles examined were found to trap PAP. Whereas the tridiniensional shapes of the trapping regions showed similar pattems according to the development of lymph follicles, their two-dimensional shapes varied. We suggest that FDCs in primary follicles may differentiate into FDCs in the light zone and FDCs in the dark zone in secondary follicles. To evaluate each of the compartments of a lymph follicle more accurately, investigators should pay attention to the tridimensional shape of the compartment.
Open Access
Alterations in the alveolar epithelium after injury leading to pulmonary fibrosis
(Murcia : F. Hernández, 1996) Kasper, M.; Haroske, G.
This review discusses current knowledge of the involvement of the alveolar epithelium in tissue remodelling during fibrogenesis. The purpose of the present paper is to give an overview, including the authors' own results, of knowledge of ultrastructural alterations, proliferation kinetics and phenotypic changes of pneumocytes in experimental and clinical pathology of pulmonary fibrosis. After lung injury, the alveolar epithelial cells show ultrastructural alterations, hypertrophy and hyperplasia, and a modulation of a series of structural and membrane proteins such as cytoskeletal changes, loss or de novo expression of epithelial adhesion molecules, and altered lectin binding. Furthermore, enhanced secretion of proteases, of cytokines and other soluble factors can be observed in the alveolar epithelium. These findings suggest the contribution of the epithelium in the remodelling process to be greater than expected. Estimations of the cell kinetics show that type 11 pneumocytes have the proliferative capacity to restore high proportions of damaged type 1 cells within few hours. In fibrosis this capacity also seems to be affected seriously, resulting in transitional phenotypes between type 11 and type 1 cells. Additionally, in the light of the detection of CD44 type of adhesion molecules at the foot processes of type 11 pneumocytes, some aspects of epithelial-fibroblast interaction are described.
Open Access
Stereology of human fetal adrenal medulla
(Murcia : F. Hernández, 1996) Bocian-Sobkowska, J.; Woíniak, W.; Malendowicz, L.K.; Ginda, Waclaw J.
Stereological studies were performed on 27 pairs of adrenal glands of human fetuses (9-38 weeks of intra-uterine development). Medullary chrornaffin cells were identified by irnrnunostaining for chromogranin-A. The volume of adrenal rnedulla, average cell volurne, and the number of chrornaffin cells were calculated. The volume of adrenal medulla increased slowly up to the 20th week and afterwards it enlarged rapidly to the 3 1 st week of the fetal period. A gradual, linear increase in the number of chromaffin cells of developing adrenal rnedulla was observed during the studied period. On the contrary, the average volurne of the adrenal medullary cells rernained quite constant until the 17th week of the development. Afterwards, a gradual, linear increase in the cell volume was observed until the 31 st week, reaching a plateau by the end of intra-uterine developrnent.
Open Access
Microgravity in the STS-29 space shuttle discovery affected the vestibular system of chick embryos
(Murcia : F. Hernández, 1996) Fermin, C.D.; Martin, D.; Jones, T.; Vellinge, J.; Deuser, M.; Hester, P.; Hullinger, R.
Out of 32 embryos flown (16 @ E2 + 16 @ E9) for 5 days, 16 survived. Al1 sixteen E2 were dead at landing. Eight were opened and eight were incubated at 1 .OG. Autopsy showed that 4 E2 survived over 24 hours in space. Eight E14 hatched without anatomical malformations, and 8 E14 were fixed. The height of the macular epithelia was 31 ym (mean) in control and 26 pm in flight chicks. The cross-sectional area of macular nuclei of control was 17 ym2 for hair cells and 14 ym2 in supporting cells. In flight, cross-sectional area was 17 pm2 in hair cells and 15 Iim2 in supporting cells (n=250). The shape factor of cartilage cells (1.0 = perfect circle) between control (mean = 0.70) and flight (mean = 0.72), and the area of cartilaginous cells between controls (mean = 9 pm2) and flight (mean = 9 Iirn2) did not differ (n=300). The nuclei of support cells were closer to the basement membrane in flight than in control chicks. The immunoreactivity of otoconia with anti keratan, fibronectin or chrondroitin sulfate was not different between flight and control ears. There were more afferent fibers inside the macular epithelia of flight (p<0.05) than control. Three of 8 flight animals had elevated vestibular thresholds (VT), with normal mean response amplitudes and latencies. Modified afferent innervation pattems requiring weeks to compensate are sufficient to elevate VT, and should be investigated further. Other reversible (sublethal) microgravity effects on sensory epithelia (vacuoles, swelling, etc) require quantification.
Open Access
Odontogenic jaw cysts: light and electron microscopical investigations
(Murcia : F. Hernández, 1996) Domenici Lombardo, L.; Amunni, F.; Bergamini, M.; Romagnoli, P.
Light and electron microscopy were used to analyze the epithelial lining of odontogenic cysts excised from edentulous regions of the jaws. Clinically, three cases were identified as keratocysts, and 21 cases as cysts other than keratocysts («non-keratocysts~)T. he epithelium of the former was found to achieve keratinization over most of the surface and to never contain mucus secreting cells. The epithelium of the latter appeared to be in part stratified squamous, with cells loosely connected to each other, and in part stratified columnar, with superficial cells connected to each other by tight junctions and secreting mucus. The results suggest that cysts arising from edentulous regions of the jaws may be either keratocysts or cysts with heterogeneous, non-keratinizing epithelium; the content of keratocysts can be formed mainly by shedding of comified epithelial layers, and that of non-keratocysts by mucus secretion from columnar epithelium associated to fluid filtration through non-keratinizing squamous epithelium.
Open Access
A comparison of cyclosporine A and cyclosporine G in a rabbit heterotopic cardiac transplant model: graft outcome and histological findings
(Murcia : F. Hernández, 1996) Fryer, J.P.; Pascoe, E.A.; Yatscoff, R.W.; Thliveris, J.A.
Cervical heterotopic heart transplants were performed on 20 male New Zealand white rabbits comprising 4 treatment groups. Animals in each group were injected daily via the marginal ear vein and received one of the following regimes: Cyclosporine A, 10 mglkglday; Cyclosporine G, 15 mglkglday; cremophor-El, 3mllday; or normal saline. Measurement of 24 hour trough blood concentrations revealed no significant differences between the average concentrations of Cyclosporine A and Cyclosporine G. Animals were examined daily and the cervical allografts assessed by palpation for viabilitylrejection. The duration of the study ended for each animal when the graft stopped beating at which time the animals was euthanized and the transplanted heart and native kidneys harvested and processed for light microscopy evaluation of rejection and drug toxicity, respectively. Graft survival in the Cyclosporine A group significantly surpassed that seen in the Cyclosporine G group as well as the control groups, whereas in animals treated with Cyclosporine G, graft survival was not different from controls. In the native kidney, there were no differences in glomerular tuft area or volume density amongst drug-treated or control animals. In contrast, tubule atrophy and interstitial fibrosis were markedly greater in Cyclosporine A-treated vs Cyclosporine Gtreated animals. The results of this study indicate that, whereas Cyclosporine G is less nephrotoxic than Cyclosporine A, given equivalent blood concentrations Cyclosporine A delays rejection of a cardiac allograft significantly longer than Cyclosporine G in this animal species.
Open Access
Architecture of the mammalian pituitary cholinergic system with observations on a putative blood acetylcholine sensor
(Murcia : F. Hernández, 1996) Caffé, A. R.
Acetylcholine ( ACh) play s an important role in pituitary gland function. Little is known, however, about the source and trajectory of pituitary ACh, the location of pituitary cholinergic receptors. and the pathways along which the release of pituitary ACh is controlled. Therefore choline acetyltransferase (ChAT) immunoreactive profiles have been investigated in the rat median eminence and pituitary. Furthermore, both muscarinic- (mAChRp-L) and nicotinic receptor proteinlike (nAChRp-L) immunoreactivity have been examined in the rat, rabbit, and cat pituitary. The results have demonstrated that the rat pituitary ChAT network is composed of neurons in the hypothalamic arcuate nucleus and a great number of terminals in the median eminence. In the pituitary, ChAT immunolabeled profiles were virtually absent. This suggests that much of the ACh acting on pituitary cells is released as a humoral factor from the median eminence. Al1 the examined animals expressed mAChRp-L immunostained endocrine cells in the intermediate lobe. Apart from this, marked species differences in AChRp-L immunolabeled profiles have been found. In addition, strong mAChRp-L immunoreactive rod to cone-shaped bodies were detected associated with blood vessels of the anterior and intermediate lobes in the rat and rabbit, but not in the cat. The immunolabeling was present in particles on the body plasma membrane. These characteristics suggest that the function of these structures might be to sense pituitary blood ACh levels. Consequently the name hlood acetylcholine reading hodies (BARBs) was adopted to indicate these stmctures. It is proposed that the BARBs may play a role in the feedback control of ACh release from the median eminence.
Open Access
Modulation of the glycoconjugate expression in the tracheo-bronchial epithelium during sustained hypovitaminosis A
(Murcia : F. Hernández, 1996) Zschabitz, A.; Weiser, H.; Stofft, E.; Gabius, H.J.; Biesalsk, H. K.
The aim of this study was to determine the influence of sustained marginal vitamin A deficiency on the morphology of glycoconjugate expression in the tracheobronchial epithelium of guinea pigs. The distribution of oligosaccharide chains was investigated by applying a panel of 24 lectins. Glycosaminoglycans were detected by histochemical techniques. Number as well as morphology of ciliated cells showed no significant alterations in hypovitaminosis A. In contrast, the quantity of goblet cells was constantly decreased. A considerable reduction of secretory granules was also observed in these cells. Cytomembranes of ciliated cells (especially in the area of ciliar extensions) showed constant alterations in the patterns of lectin binding in vitamin A-depleted guinea pigs. Our results demonstrate a significant augmentation of accessibility of fucosyl molecules in proximal domains of glycoconjugates of ciliary membranes, whereas the presence of mannose structures seemed unchanged. In dista1 bronchioli, terminal Nacetylgalactosamine molecules were expressed. During marginal vitamin A deficiency, ciliary cells were specially labelled by GSA IB, indicating presentation of terminal galactose molecules in a-position. Additionally, the cytoplasm of epithelial cells demonstrated enhanced concentrations of polyantennary oligosaccharide core structures. Staining of epithelial cells by VVA was restricted to control specimens. Abundance of Nacetylglucosamine residues on the non-reducing terminus of oligosaccharides was significantly enhanced in the connective tissue of depleted animals as demonstrated by the binding patterns of GSA 11. We suggest that altered oligosaccharide patterns may contribute to enhanced predisposition to tracheobronchial infection in marginal vitamin A deficiency.
Open Access
Pattern of degeneration of the rat inferior olivary complex after the early postnatal axotomy of the olivocerebellar projection
(Murcia : F. Hernández, 1996) Armengol, J.A.; López-Román, A.
Neuronal death of inferior olivary neurons after early axotomy of the olivocerebellar tract was studied in newborn (Pl) hemicerebellectomized rats during the first six days after lesion. The degeneration of the inferior olive showed a topographic pattem from one (P2) to six days after axotomy (P7), after which this complex had almost completely disappeared. The first degenerative changes were observed in the principal olive (P2), while the media1 accessory olive was the later-degenerated area (P5). The analysis of these degenerative changes provides a reference for future experimental studies. Furthermore, the topographic study of the degenerative process demonstrated that: i) the most vulnerable neurons were dorsolaterally located, whereas the most resistant ones occupied the media1 aspect of the inferior olivary complex, ii) the comparison between the topographical arrangement of the inferior olivary neurons according to their birth dates, and the rate of degenerative changes observed after hemicerebellectomy, open the possibility that the neurona1 generation date and the response to the axotomy of the inferior olivary neurons could be related.
Open Access
Ultrastructural localization of substance P-like immunoreactivity in the intermediolateral column of spontaneously hypertensive rats and Wistar-Kyoto rats
(Murcia : F. Hernández, 1996) Tan, C.K.; Tang, F.R.; Ling, E. A.
The distribution of substance P in the intermediolateral column of the upper thoracic spinal cord of spontaneously hypertensive (SHR) rats and Wistar-Kyoto (WKY) rats was studied by combined retrograde tracing of choleragen subunit-B horseradish peroxidase (CB-HRP) and immuno-electronmicroscopy. In the TI-T3 segments of the spinal cord, SP-like immunoreactive products were localized in the cell bodies and dendrites of the sympathetic preganglionic neurons as well as in a few pre-axon terminals or axon terminals. In the neuropil of the intermediolateral column (ILN), different synaptic configurations were observed including synaptic contacts between SP-like positive dendrites and negative axon terminals, and between SP-like positive axon terminals and SP-like positive dendrites. Furthermore, a single SP-like positive dendrite was sometimes postsynaptic to severa1 axon terminals, a feature typical of glomerular synapses. The present findings suggest that most of the SP-like immunoreactive elements in the ILN were of intraspinal origin derived mainly from the sympathetic preganglionic neurons in SHR and WKY rats. Since there was no ultrastructural difference in the distribution of SP between the neural elements in the ILN of SHR and WKY rats, the present findings also suggest that SP may not be directly involved in the hyperactivity of the sympathetic nervous system in hypertension.
Open Access
Nonerythroid membrane skeletal proteins in normal and diseased human skin
(Murcia : F. Hernández, 1996) Shimizu, T.; Takakuwa, Y.; Koizumi, H.; Ohkawara, A.
A number of reports have described the presence and localization of membrane skeletal proteins in nonerythroid tissues and cultured cells. Interactions of these proteins, which have been extensively characterized in erythrocytes, may be physiologically important in other cell types. This review focuses on recent developments concerning proteins analogous to erythrocyte spectrin, protein 4.1, adducin and ankyrin in epidermal keratinocytes, and discusses their significance from physiological and pathological stand points. Keratinocyte proteins are involved in a wide variety of functions such as the cell-to-cell and cell-to-substratum adhesion, stratification, and maintenance of the cell shape. In epidermal keratinocytes, these nonerythroid membrane skeletal proteins may play a role in maintaining the polarity of membrane proteins by connecting them to the cytoskeleton, regulating cell-cell interdigitations and stabilizing newly synthesized cell membranes before elaboration of cell-cell interdigitations. Furthermore, altered expression and distribution of these proteins may be important in the pathogenesis of skin disease such as psoriasis.
Open Access
Tenascin and type IV collagen expression in liver cell dysplasia and in hepatocellular carcinoma
(Murcia : F. Hernández, 1996) Zhao, M.; Laissue, J.A.; Zimmermann, Astrid
The extracellular matrix (ECM) located in and around tumors is different from normal organ stroma, and there is evidence that it is critically involved in carcinogenesis and malignant growth. Whereas an abnormal composition of ECM in hepatocellular carcinomas (HCC's) has previously been demonstrated, not much is known so far with respect to putative HCC precursor lesions. We have, therefore, systematically analyzed the immunohistochemical reactivity for two major ECM components, tenascin and type IV collagen, in three types of liver cell dysplasia (LCD), and compared the findings with patterns observed in HCC's of different types and grades. Tenascin reactivity was generally stronger in HCC's than in cirrhosis. In cirrhotic nodules harboring areas of LCD, tenascin expression was significantly lower in small cell LCD than in large cell LCD. Type IV collagen reactivity in and around HCC's decreased as a function of a lower differentiation grade. In both groups of cirrhosis, ¡.e. with or without HCC, cirrhotic nodules occupied by the small cell variant of LCD exhibited a significantly lower type IV collagen reactivity than those with large cell LCD or simple regenerative cells. Taken together these findings suggest that, similar to adenomatous hyperplasia, small cell LCD is characterized by an abnormal tenascin and type IV collagen expression, thus reflecting the defective ECM pattern observed in HCC's.
Open Access
Seasonality and freezability vs routine parameters in stallion semen
(Murcia : F. Hernández, 1996) Rodríguez, H.; Bustos-Obregón, E.
The fertilizing ability of stallion semen was analyzed using fresh and frozen samples, obtained before (June-July) or during (October-November) the breeding season. Thirty ejaculates obtained from 4 stallions, were used. The analysis comprises routine seminogram; ATP concentration (Comhaire et al., 1983); subjective and objective motility and sperm velocity (Makler, 1980). Freezing was done following the technique of Martin et al. (1979). Sperm velocity, ATP content and objective motility in ejaculates of subjective motility >50% show values of 14.010.84 ym S-l; 4.8f 2 . 7 1~O - ~ Man d 54.0I7.4%, respectively. For ejaculates with subjective motility ~ 5 0 %the~se values are 8.412.4; 0.74f 0 . 3 6 1~ 0 - 7 a~n d 27.0+0.8%. No significant changes in these characteristics were elicited by freezing, though ATP content dropped to 50% after thawing. These characteristics are highly associated between them (pc0.05) and with some conventional parameters of the routine seminogram such as sperm motility, count, total spermatozoal number and morphology. Additionally, sperm chromatin packing was analyzed by decondensing sperm nuclei using a thiol reducing agent. This parameter was not modified by freezing and it may depend on prolonged epididymal sperm storage during the non-breeding season. Epididymal maturation then results in an excessive disulphur bridging in sperm basic proteins, so that hypermaturation with faultly male pronuclear formation can follow.
Open Access
Facts and paradoxes in current notions of nuclear organization and function
(Murcia : F. Hernández, 1996) Manfredi Romanini, M.G.; Fraschini, A.
Invisible compartments, identified rather by their activities than by their morphology, seem to operate in the nucleus. These compartments interrelate somehow, including mediation by the nuclear matrix. As our knowledge about the nucleus increases, more paradoxes become evident. We here consider some of them: 1) the well-known C-paradox of Cavalier-Smith, conceming the disproportionate amount of nuclear DNA content in comparison with the amount of DNA potentially able to transcribe; 2) the DNA folding in the chromatin fibre and its superorganization within the nucleus, which seems to be in opposition with the transcribing and self-replicating activities; 3) the elusive role of the DNA sequences with different degrees of repetitivity; and 4) the compartmentalization in the nucleus and how it relates to transcription, processing and transport of transcripts, and to DNA reduplication. We conclude by introducing the concept of species specific, minimal, but essential genome components, ¡.e. the elusive few thousand DNA bases that, in our hypothesis, act as a functional bridge between the nuclear matrix and chromatin.
Open Access
Expression of transforming growth factor í3 isoforms and their receptors during hair growth phases in mice
(Murcia : F. Hernández, 1996) Wollina, Uwe; Lange, D.; Funa, K.; Paus, R.
Transforming growth factor B (TGF-6) is a family of potent growth inhibitor proteins, often produced as a precursor and often secreted in a complex with the latent TGF-B binding protein (LTBP). We investigated the expression of TGF-B1, 42, 43, LTBP, TGF-B receptor proteins type 1 and type 11 (TBR-1 and -11) during induced hair growth in C57 BL-6 mice. We here demonstrated that TGFBs and TBR-1 are expressed in hair follicle epithelium and have found a positive reactivity for LTBP and TBR-1 in sebocytes. Dermal tissue was weakly stained for LTBP and TGF-B3. In early anagen the inner hair root sheath epithelium expressed TGF-B1, whereas outer hair root was positive for TBR-1 during anagenlcatagen switch. TER-11 was found in sebaceous glands without significant variations during the hair cycle. We may conclude that in follicle epithelium TGF-Bl is not produced in a complex together with LTBP. On the other hand, it is possible that other types of LTBP, like LTBP-2 and LTBP-3, are present, which are not detected by the antibody we used. Furthermore, a very rapid secretion of LTBP fromproducing cells may prevent immunohistochemical detection. TGF-Bl released by inner hair root sheath may regulate outer root sheath growth. A bidirectional interaction of sebocytes and hair follicle epithelium in the TGF-BILTBP seems possible. Sebocytes can be considered to be a target for TGFs since they express both TBR-1 and -U. The general properties of TGF-B as a growth inhibitor of epithelial cells may suggest a possible involvement in either the abrogation of extensive growth at the end of anagen or the initiation of catagen for the follicle epithelium as well as growth control for sebaceous glands.