Biomedical subjects
C Viebahn
Publications and source records attributed to C Viebahn.
Intermediate filaments in Sertoli cells.
Using immunohistochemical techniques both at light and electron microscopic levels, the arrangement and distribution of intermediate filaments in Sertoli cells of normal testis (in rat and human), during pre- and postnatal development (in rabbit, rat, and mouse) and under experimental and pathological conditions (human, rat), have been studied and related to the pertinent literature. Intermediate filaments are centered around the nucleus, where they apparently terminate in the nuclear envelope providing a perinuclear stable core area. From this area they radiate to the plasma membranes; apically often a close association with microtubules is seen. Basally, direct contacts of the filaments with focal adhesions occur, while the relationship to the different junctions of Sertoli cells is only incompletely elucidated. In the rat (not in human) a group of filaments is closely associated with the ectoplasmic specializations surrounding the head of elongating spermatids. Both in rat and human, changes in cell shape during the spermatogenic cycle are associated with a redistribution of intermediate filaments. As inferred from in vitro studies reported in the literature, these changes are at least partly hormone-dependent (vimentin phosphorylation subsequent to FSH stimulation) and influenced by local factors (basal lamina, germ cells). Intermediate filaments, therefore, are suggested to be involved in the hormone-dependent mechanical integration of exogenous and endogenous cell shaping forces. They permit a cycle-dependent compartmentation of the Sertoli cell into a perinuclear stable zone and a peripheral trafficking zone with fluctuating shape. The latter is important with respect to the germ cell-supporting surface of the cell which seems to limit the spermatogenetic potential of the male gonad.
Expression and organization of muscle specific proteins during the early developmental stages of the rabbit heart.
The expression and intracellular distribution patterns of muscle-specific proteins were studied during rabbit embryo development (7-13 dpc) using monoclonal antibodies against titin, myosin, tropomyosin and actin, as well as the intermediate filament proteins desmin, keratin and vimentin. From our panel, titin appeared to be the first muscle-specific protein to be exclusively expressed in the embryonic rabbit heart. Upon differentiation (myocyte and myotube formation), titin reorganizes from dot-like aggregates into a cross-striated pattern (in 9- to 30-somite embryos) via a transiently filamentous distribution. When the expression and organization of the other muscle proteins was studied in relation to titin, it became apparent that tropomyosin followed upon titin with respect to its exclusive expression in the heart anlagen and its organization into a striated pattern. Myosin and desmin were organized into cross-striated patterns after titin and tropomyosin, but this arrangement had not reached its final form in 13-dpc embryos. Actin, keratin and vimentin were distributed in cytoplasmic filaments in the embryonic stages we investigated. Since the first pulsations are already detected in 3-somite embryos, we conclude that the organization of titin, tropomyosin, myosin and desmin into a striated pattern does not seem to be essential for the initiation of muscle cell contraction in the heart anlagen. Furthermore, this study shows that, in comparison with studies on mouse, chick and rat, the sequence of expression of muscle-specific and intermediate filament proteins during cardiomyogenesis is species-dependent, and that their expression and organization varies in time in different regions of the developing heart.
Cytokeratin expression and early lens development.
Immunohistochemical analysis of cytokeratins and vimentin in human, rabbit and rat lens epithelium during development revealed transient coexpression of both types of intermediate filaments. Cytokeratins were still detectable after the closure of the lens vesicle (rat and rabbit embryos 13 days post conception) and in the epithelial cells located at the anterior side of the lens in 7-week-old human embryos. Different monoclonal antibodies against cytokeratin 8 reacted differently in lens cells but not in other embryonic tissues. In addition, early human and rabbit specimens exhibited cytokeratin immunostaining in the neuroectodermal cells of the eye cup as well as in the surrounding mesenchyme, and in the hyaloid artery. Possible explanations for the loss of cytokeratins during the differentiation of ectodermal and neuroectodermal cells are discussed.
Fine structural characteristics of testicular cord formation in the developing rabbit gonad.
This paper presents morphological (light- and electron-microscopical) evidence for the role of the mesonephros in contributing cells to the differentiating indifferent gonad and, after sexual differentiation, to the testis. A continuous process is revealed during which segregation of cells occurs from the developing and regressing mesonephros. Additionally, the complementary role of the coelomic epithelium in gonadal ridge and testis formation is demonstrated. The differentiation of testicular cords, their remodelling from a primary reticulum, and the composition and further change of the cellular content during the period after sexual differentiation is described using a computer-aided three-dimensional reconstruction system. Apart from these morphogenetic events, cytodifferentiation in the somatic cells of the indifferent gonad and of the early differentiated testis is demonstrated using indirect immunofluorescence in combination with monoclonal antibodies to the intermediate filament proteins keratin 8 and 18 and vimentin. The immunohistochemical results show that different forms of cytodifferentiation coexist among the somatic cells present in the indifferent gonad and in the testis early after sexual differentiation.
Vimentin and keratin are expressed in the neurogenic tissue of the rabbit embryo during primary neurulation.
Against the commonly held belief that differential expression of keratins is a sign of neurogenic commitment amongst ectodermal cells of the early vertebrate embryo we show here that the same keratins (8 and 18) are expressed in the epidermal ectoderm and the neurectoderm throughout primary neurulation of the early rabbit embryo, i.e. between 8.5 and 11 days post conceptionem (d.p.c.). However, keratin expression decreases during this developmental period and, by the time primary neurulation is completed, keratin expression is virtually absent in the cells of the neural tube. Vimentin expression is weak, at first, but increases in a reciprocal manner as compared to the decreasing keratin expression until it has reached a high and stable level of expression in the established neural tube of the 10 to 11 day old rabbit embryo.
Correlation between differences in the structure of dendrite bundles and cytoarchitectonic patterns in the cerebral cortex of the rabbit.
The bundling patterns of apical dendrites are investigated in the neocortex of adult rabbits using 10-15 microns paraffin serial sections. In order to extend observations to 12 neocortical areas, four vertical planes of sectioning differing with regard to their angle with the frontal plane are chosen. In alternate sections, stained with either Klüver-PAS or a modified Gomori-method, the shape and structure of dendrite bundles are investigated in relation to the cytoarchitectonic pattern. In all 12 areas, bundling of apical dendrites is found both in lamina IV and II/III. Differences in bundle structure are found to be more pronounced amongst bundles in lamina IV than in lamina II/III. The principal difference between the bundling patterns in the precentral (motor) and occipital (visual) areas known from previous studies is confirmed, i.e. in the precentral areas short and stout bundles with a complex arrangement of apical dendrites are encountered, whereas in the occipital areas long and slender bundles with a simpler alignment of dendrites are found. Bundling patterns in the temporal cortex resemble the ones found in the occipital areas, whereas in the postcentral areas bundles are seen which show characteristics common to bundles of both the precentral and occipital areas.
A modified anti-roll plate as a remedy for the ill-effects of electrical charge during cryosectioning.
This report describes problems commonly encountered in cryosectioning of fragile tissues, such as jamming and scrambling of sections between knife and anti-roll plate. The electrostatic nature of the factors causing these derangements is demonstrated here using simple methods, and several modifications to the anti-roll plate surface are tested for their help in obviating these difficulties. The anti-roll plate material found to be most effective consists of a metal oxide-coated glass which is commercially available at low cost.
Desmin and titin expression in early postimplantation mouse embryos.
The expression of the intermediate filament (IF) constituents desmin, vimentin and keratin, as well as the striated-muscle-specific marker titin, was studied in mouse embryos of 8.0 to 9.5 days post coitum (d.p.c.), using the indirect immunofluorescence technique in combination with polyclonal and monoclonal antibodies. During the development of the embryo, desmin was first detected at 8.25 d.p.c. in the ectoderm, where it was transiently coexpressed with keratin and vimentin. At later stages, the ectoderm contained only keratin and to a certain extent also vimentin IF. At 8.5 d.p.c., desmin was found exclusively in the heart rudiment, and remained present with increasing intensity in the myocardial cells during later cardiogenesis. Striation of desmin in the heart muscle cells was observed in 9.5 d.p.c. embryos. At these stages (8.5-9.5 d.p.c.), triple expression of the IF proteins desmin, vimentin and keratin was evident in these cells. From 9.0 d.p.c. onwards, desmin could be detected in the myotomes as well. Immunoblotting studies of 9.5 d.p.c. mouse embryos confirmed the immunohistochemical data. Titin was found in the early heart anlage at stage 8.25 d.p.c., when no desmin expression was observed in this tissue. At this stage the titin appeared in a punctate pattern, similar to that observed in cardiac myofibrils of early chicken embryos (Tokuyasu and Maher, 1987; J. Cell Biol. 105, 2781-2793). In 8.5 d.p.c. mouse embryos, this punctate titin staining pattern was still observed, while, at this stage, a filamentous staining reaction could be seen with the desmin antibodies. During further development, cross-striation was detected within myocardial cells using the polyclonal titin antibody from 9.0 d.p.c. onwards, i.e. before such striation could be detected with the desmin antibodies. From these data, we conclude that titin synthesis may anticipate desmin expression in the developing mouse myocard, although the level of expression of the former protein remains low until 9.0 d.p.c.
Keratin and vimentin expression in early organogenesis of the rabbit embryo.
The expression of vimentin and keratins is analysed in the early postimplantation embryo of the rabbit at 11 days post conceptionem (d.p.c.) using a panel of monoclonal antibodies specific for single intermediate filament polypeptides (keratins 7, 8, 18, 19 and vimentin) and a "pan-epithelial" monoclonal keratin antibody. Electrophoretic separation of cytoskeletal preparations obtained from embryonic tissues, in combination with immunoblotting of the resulting polypeptide bands, demonstrates the presence of the rabbit equivalents of human keratins 8, 18, and vimentin in 11-day-old rabbit embryonic tissues. Immunohistochemical staining shows that several embryonic epithelia such as notochord, surface ectoderm, primitive intestinal tube, and mesonephric duct, express keratins, while others (neural tube, dermomyotome) express vimentin, and a third group (coelomic epithelia) can express both. Similarly, of the mesenchymal tissues sclerotomal mesenchyme expresses vimentin, while somatopleuric mesenchyme (abdominal wall) expresses keratins, and splanchnopleuric mesenchyme (dorsal mesentery) expresses both keratins and vimentin. While these results are in accordance with most results of keratin and vimentin expression in embryos of other species, they stand against the common concept of keratin and vimentin specificity in adult vertebrate tissues. Furthermore, keratin and vimentin are not expressed in accordance with germ layer origin of tissues in the mammalian embryo; rather the expression of these proteins seems to be related to cellular function during embryonic development.
The mesonephric (wolffian) and paramesonephric (müllerian) ducts of golden hamsters express different intermediate-filament proteins during development.
We analysed the expression of intermediate-filament proteins in the developing mesonephric duct (the precursor of the male genital ducts) and the paramesonephric duct (the precursor of the female genital ducts) of golden-hamster embryos using immunohistochemical methods. Embryos were investigated from the early stages of duct development, i.e. at 9.5 days post conceptionem (dpc), through sexual differentiation, until birth (15.5 dpc). Monospecific antibodies to vimentin or keratins 7, 8, 18 or 19 as well as two keratin antibodies that are pan-epithelial in human tissues were tested. Both ducts expressed vimentin to some degree from their early stages (mesonephric duct from 9.5 dpc onwards; paramesonephric duct from 10.5 dpc onwards) until birth. No keratins were detectable at these earliest stages. In the mesonephric duct, keratins 7, 18 and 19 appeared simultaneously at 10.5 dpc and persisted until birth. In the paramesonephric duct, only keratin 18 was detectable at first (at 12.0 dpc), with the expression of keratins 7 and 19 being delayed until 14.5 dpc. This feature was irrespective of sexual differentiation, which begins at 11.0 dpc, so that, in males, these keratins appeared on cue, even though the paramesonephric duct was regressing at this time. The expression of keratin 8 could not be demonstrated in either duct using the antibodies tested in our study. By 14.5 dpc, the differentiated male mesonephric duct and the differentiated female paramesonephric duct exhibited the same intermediate-filament protein pattern (weak vimentin expression and strong expression of keratins 7, 18 and 19), in spite of differences in the intermediate-filament protein patterns exhibited by the two ducts during early development. These different programmes of intermediate-filament protein regulation do not support the concept that the mesonephric duct makes a cellular contribution to the paramesonephric duct during the development of the latter.
Dendrite bundles in lamina II/III of the rabbit neocortex.
The present investigation systematically analyzes the course and arrangement of dendrites in lamina II/III of the visual and the motor cortex of the rabbit on the basis of Klüver-PAS stained 10 micron paraffin sections, 1 micron plastic-embedded semithin sections and ultrathin sections. In both areas the dendritic pattern of lamina II/III is characterized by vertical bundles reminiscent of the pattern in lamina IV/V. The bundles form in the upper half of lamina II/III. They consist mainly of apical dendrites from lamina II/III pyramidal cells and receive branches from dendrite bundles in lamina IV/V, i.e., branches from apical dendrites arising from lamina V pyramidal cells. Besides these features in common, the lamina II/III bundles in the visual cortex on the one hand and in the motor cortex on the other differ with regards to the size and shape of individual bundles as well as to the extent of connections with bundles in lamina IV/V.
[Anastomosis healing in the irradiated colon. III. Microangiographic studies. An animal experiment study].
During an experimentation on animals, the vascularization of anastomoses in the recto-sigmoidal region was investigated by microangiographic examinations after an irradiation corresponding to the therapeutic proceeding in man. The anastomoses were performed with and without fibrin coating one day, four weeks, eight weeks and four months following to irradiation. The examinations were performed on the third, seventh, 14th, and 21th postoperative day. The results of microangiography do not show any difference between irradiated and non-irradiated animals.
[Direct magnification radiography using a highly intensifying screen].
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[Study about the healing of anastomoses in the irradiated colon--experimentation on animals (author's transl)].
Operations on preirradiated intestinal segments are followed by a high rate of complication. In order to determine the period after which an anastomosis on the clinically/therapeutically irradiated colon involves the greatest risk, 230 rats were submitted to a fractionated X-ray stationary-field irradiation of the colon with 50 Gy. The colon was anastomosed one day, four weeks, eight weeks, and four months respectively after the irradiation. A possible protective influence of fibrin on the healing of anastomoses was examined. The resistance to bursting pressure is taken as a criterion of the security of the anastomosis. It was determined on the third, 7th, 14th, and 21st day after the operation. The irradiation alone produces a markedly higher resistance to bursting pressure in the not operated control animals. After presurgical irradiation, the healing of anastomoses is delayed. There is no dependence on the period of time between irradiation and operation. From the 14th day after surgery, the resistance to bursting pressure is considerably higher than initially. In our experiment, the healing of anastomoses was not improved by an additional fibrin application.
[Late radiation damage in the intestine. Clinical aspects, therapy and prognosis (author's transl)].
The causes, incidence, symptoms, treatment and prognosis of late radiation damage of the intestine are reported with reference to the literature. The possibilities of elimination are discussed. From 1969 to 1979, 48 of our own patients (34 women and 14 men) were operated for radiogenic late sequelae of the intestine. 27 of these patients required emergency laparotomy. The high mortality of around 42% is essentially due to fecal peritonitis already present at the time of operation.
Short-term regulation of LH and FSH secretion in cyclic women. III. Effects of varying doses of two consecutive LH-RH injections on pituitary and ovarian response.
The effects of two consecutive LH-RH injections at 120 min intervals with either a varying first or second LH-RH dose on pituitary gonadotrophin response were investigated in 15 eugonadal women to study pituitary secretory processes. Each volunteer underwent a total of 4 LH-RH double stimulation tests. In group I (n = 8) the first LH-RH dose of each of the 4 tests was fixed at 25 microgram, whereas the second LH-RH dose consisted of either 6, 25, 100 or 400 microgram. In group II (n = 7) the first LH-RH dose varied between 6 and 400 microgram, while the second LH-RH dose was kept constant at 25 microgram. Serum gonadotrophin and serum ovarian steroid levels were determined by radioimmunoassay before and after LH-RH administration. The volunteers in both groups served as their own controls. A linear log-dose response relationship was found between the various doses of LH-RH injected and the corresponding LH and FSH elevations elicited. However, the dose of the first LH-RH injection also significantly influenced the gonadotrophin reaction after the second LH-RH injection in a linear log-dose response relationship. Serum levels of oestradiol, 17-hydroxyprogesterone and progesterone significantly increased in response to the elevated serum gonadotrophin levels after LH-RH stimulation during the 4 h test period, but the rise did not correlate to the LH-RH dose used. The results indicate that LH-releasing hormone stimulates not only the release, but also the synthesis of LH and FSH in a dose-related manner. These findings are consistent with our previously reported concept that the magnitude of LH and FSH response to the first LH-RH injection reflects the "storage capacity", while the increase observed after the second LH-RH injection represents the "synthesis capacity" of the gonadotrophs.