FSH-induced aromatase activity in hamster granulosa cells: effect of estradiol-17β in vitro

Summary We have shown previously that estradiol-17 (E₂) reduces number of ovulations in cyclic rats, induces atresia of the dominant preovulatory follicle in monkeys, and that the initial effects of this treatment include reduced viability and estrogen accumulation in vitro by aspirated granulosa cells (GC) from monkeys and hamsters. The present experiment was designed to determine whether the reduction in estrogen accumulation can be ascribed to a direct action of E₂ on the aromatization of androgen to estrogen in vitro. Female hamsters were injected with 30 I.U. pregnant-mare serum gonadotropin i.p. and sacrificed 3 days later. GC were aspirated from the largest follicles and incubated for 48 h (initial incubation period) in the presence of human pituitary follicle-stimulating hormone (hFSH, 100 ng/ml). Following initial incubation, GC were further incubated for up to 24 h (secondary incubation period). During this subsequent incubation, medium was supplemented with 100nM ³H-1-androstenedione (³H-A₄). Initial incubation with E₂ at doses of 10 ng/ml, 100 ng/ml and 1 m E₂/ml induced variability in GC response, and a maximal depression of 70%. The inhibition by E₂ of hamster GC function in vitro parallels that shown in vivo for both hamsters and monkeys, but contrasts with that shown for rats. Thus, hamsters may represent an appropriate model in which to study the atretogenic effects of E₂ directly on antral follicle development.     

Calcitonin gene-related peptide immunoreactivity in airway epithelial cells of the human fetus and infant

Summary Calcitonin gene-related peptide-immunoreactive cells were identified within the epithelium of distal conducting airways in the human fetus and infant. Several peptides and amines, including calcitonin, have been identified previously within a specific population of airway epithelial cells. These cells, referred to as pulmonary neuroendocrine cells, are postulated to be airway chemoreceptors responsible for changes in ventilation and perfusion in response to changes in airway gas composition. Calcitonin gene-related peptide immunoreactive cells could be identified throughout the period of development studies (20 weeks gestation to 3 months of age), but were present in only limited numbers in less than 50% of individuals (n=23). In contrast, large numbers of calcitonin gene-related peptide immunoreactive cells were identified in 100% of infants (1–3 months, n=5) with bronchopulmonary dysplasia. The differential processing of mRNA transcribed from the calcitonin gene in neural and non-neural tissue suggests that calcitonin, rather than calcitonin gene-related peptide, is the primary product of translation in pulmonary neuroendocrine cells. However, considering the potent vasodilatory and bronchoconstrictive effects of calcitonin gene-related peptide, its presence in pulmonary neuroendocrine cells, even in small amounts, may be important in controlling pulmonary vaso- and/or bronchomotor tone. The presence of large numbers of calcitonin gene-related peptide immunoreactive cells in infants with bronchopulmonary dysplasia suggests that calcitonin gene-related peptide may be one further agent contributing to the pulmonary pathophysiology seen in this disease.     

Surface charges of the membrane and cell adhesion substances determine the structural integrity of hair bundles from the inner ear of fish

Summary The hairs (stereocilia = stereovilli) of sensory cells from the inner ear of vertebrates are interconnected by several types of connectors, whose role is unknown. They appear to stabilize the hair bundle mechanically, and may be directly involved in mechano-electric transduction. Our transmission electron-microscopical investigation of sensory epithelia from two species of fish (Rutilus rutilus, Scardinius erythrophthalmus, both Leuciscidae) has shown that not only the connectors but also the surface charges of the membrane are important factors for determining the shape of the hair bundle and the spatial interrelation of the stereovilli. A reduction of the ionic strength in the medium leads to an increase in distance between the stereovilli. This may be the result of an extension of the spread of the surface potential of the membrane at low ionic strength. The connectors are not broken by the increase in distance between the stereovilli. They are EDTA (ethylene-diamine-tetra-acetic-acid) resistant as are some cell adhesion molecules such as N-CAM (nerve-cell adhesion molecule) and protein A from Dictyostelium discoideum. The connectors do not prevent polycation-induced fusion of adjacent stereovillar membranes.     

Distribution and fine structure of ependymal cells possessing intracellular cysts in the aqueductal wall of the rat brain

Summary The wall of the cerebral aqueduct was examined in 20 male rats at the light- and electron-microscopic levels. Disorder in ciliary orientation was occasionally seen in ordinary ependymal cells. Ependymal cells possessing intracellular cysts of 5 to 30 urn in diameter were observed within and beneath the aqueductal ependyma in all animals examined. Light-microscopic reconstruction from serial, 10-m thick frontal sections revealed an extensive distribution of cystic ependymal cells (CECs), especially along the ependymal ridges in the rostral half of the aqueduct, and along the dorsal region of the aqueductal lining in the caudal half. Both cystic and surface membranes of CECs bore microvilli and cilia. Ectopic ependymal cells (EECs) characterized by densely packed microvilli, well-developed intermediate junctions and cilia, but without cysts, were situated in the subependymal region adjacent to a CEC or another EEC. The ependymal ridges were long, narrow and sporadically stratified ependymal linings extending rostrocaudally and bilaterally along the aqueductal surface. Tanycyte-like cells filled the surface region of the ridge, and CECs and EECs were frequently seen in the core. Intraventricularly injected microperoxidase was detected among densely packed microvilli but not in the cystic lumina of CECs, indicating that EECs and CECs are distinct entities.     

Origin of regenerating Leydig cells in the testis of the adult rat

Summary Ethane dimethanesulphonate (EDS) was used as a specific cytotoxin to eliminate the Leydig cell population of the adult rat testis. Ultrastructural, morphometric and serum gonadotrophin and testosterone analysis was used to study the response of the intertubular tissue of the testis from 1 day to 10 weeks after EDS treatment. In control animals, the testis contained approximately 28 million Leydig cells and 8 million macrophages. Three to seven days after EDS treatment, Leydig cells were absent and serum testosterone was undetectable. Macrophage numbers increased three-fold by 3 days and returned to pretreatment values thereafter. At 2 and 3 weeks post-EDS, foetal-type Leydig cells (1–2 million per testis) appeared in proximity to perivascular and peritubular tissues, a feature also observed at 4 weeks when numerous such cells (15 million per testis) formed prominent clusters in perivascular and peritubular locations. Between 6 and 10 weeks after EDS treatment, the foetal-type Leydig cells were transformed morphologically into adult-type Leydig cells, they occupied central intertubular positions and their numbers were restored to pretreatment values. Regeneration of Leydig cells was reflected by elevated serum testosterone levels which returned towards the normal range. The results demonstrate the regenerative capacity of the testicular intertubular tissue and indicate a dual site of origin of Leydig cells which initially resemble foetal-type Leydig cells prior to establishing the adult-type Leydig cell population. The morphological pattern of Leydig cell regeneration suggests that in addition to gonadotrophic stimulation, local testicular factors from the seminiferous tubules may stimulate Leydig cell growth.     

Mutagenicity,sister chromatid exchange inducibility andin vitro cell transforming ability of particulates from Athens air

Airborne particulates were collected over a period of twelve months by the use of Hi-Vol samplers in the basin of Athens, Greece. N-Hexane extracts were tested in a battery ofin vitro tests for their ability to induce mutation in bacteria as well as mutation, sister chromatid exchange and morphological transformation in cultured mammalian cells. Positive results were found for mutagenicity withSalmonella strain TA98 in the Ames assay, for sister chromatid exchange induction in CHO cells and for transformation in BALB/c 3T3 cells in culture. They also showed weak non-doserelated induction of ouabain resistance in BALB/c 3T3 cells. The contribution of oxidizing and nitrating agents found in the Athens atmosphere, together with sunlight UV irradiation in the formation of direct acting mutagens and potential carcinogens from ambient polycyclic aromatic hydrocarbons, is suggested.Abbreviations FCS fetal calf serum - FPG fluorescent-plus-Giemsa technique - oua^R ouabain resistant - PAH polycyclic aromatic hydrocarbon - SCE sister chromatid exchange - TSP total suspended particulate     

Investigation of histone proteins in plant nuclei possessing different ultrastructural organization

Summary According to Nagl and Fusenig (1979) the structure and ultrastructure of plant nuclei is species-specific and is determined by the DNA (2C) value and the amount of the repetitive DNA. Light and electron microscopic observations ofZea mays L.,Pisum sativum L., andPhaseolus vulgaris L. nuclei led us to define their organization as chromonematic, chronomeric and chromocentric, respectively. Nuclear proteins, soluble in 0.4N H₂SO₄ and 0.74M HC1O₄, were extracted from isolated nuclei and resolved according to their solubility and mobility in SDS and acetic acid-urea PAGE and 2D-Triton X 100 PAGE. Differences in the variants (and modifications) of the H 1 histone class and the nucleosomal H 2 A, H 2 B, and H 3 isoforms probably reflect that species-specific nuclear ultrastructure is based, not only on the heterogeneity and the quantity of DNA, but also on the diversity of the protein component of chromatin.Abbreviations MES Morpholinoethane sulfonic acid - PMSF phenylmethylsulphonyl fluoride - DMSO dimethylsulfoxid - SDS sodium dodecylsulfate - TEMED N, N, N N-tetramethylethylen-diamin - PAGE polyacrylamide gel electrophoresis     

Leydig cell mitoses in human testes bearing early germ cell tumors

Summary Numerous mitoses were noted in testicular tissue from adult men with early germ cell tumors. More than 15 Leydig cells undergoing mitosis were found in the interstitial compartment. The presence of specific crystalline intracytoplasmatic inclusions demonstrated for the first time that differentiated Leydig cells are capable of proliferation. Occasionally cells are difficult to discriminate during mitosis. To establish reference criteria, the light- and electron-microscopic features of the following mitotic cells were examined: Leydig cells, fibroblasts, perivascular cells, peritubular cells, and lymphocytes. Supplementary mitoses in germ cell tumors and in a case of Leydig cell tumor were investigated. In the literature, only single reports of mitoses in Leydig cells are available. The frequent incidence of Leydig cell mitosis in early germ cell tumors may be due to the presence of growth-promoting factors in the testicular tissue.     

Vasoactive intestinal polypeptide-like immunoreactivity in the bovine heart: high degree of coexistence with neuropeptide Y-like immunoreactivity

Summary Recent studies have accomplished the establishment of a collagenous fiber-fringe matrix upon dental root surfaces in vitro. The present study was undertaken to follow the development of such a matrix in vitro and to test the possible effects of root surface treatments upon this matrix. Periodontal ligament cells, 0.1 to 0.2-mm thick dental root discs, and alveolar bone cells were derived after extraction from four partially erupted third molars and the accompanying interradicular bony septa of 1 male patient. Autologous serum was obtained by venipuncture. Cultures were initiated by delivering a 1-ml suspension of 50000 tritiated thymidine-labeled periodontal ligament cells and 50000 alveolar bone cells onto each of 42 culture sets. The following day, demineralized or non-demineralized root discs treated with autologous serum, fibronectin or complete medium were placed in pairs, separated by a 0.1–1.0 mm gap, upon the initial cell layer. Representative cultures were terminated after 2, 3, 4, 5 and 6 weeks, and processed for light- and electron microscopy, morphometric analysis and autoradiography. An outstanding feature of the early cultures (2, 3 and 4 weeks) was a patchwise, random distribution of matrix making a precise developmental study impossible, although collagen fibrils were produced within the first 2 weeks. Some 3-week cultures already demonstrated a mature fiber-fringe characterized electron-microscopically as oriented, densely packed collagen fibrils closely abutting the cementum-lined root discs. The treatments (including autologous serum) used in this study had no appreciable morphologic or morphometric effect upon the fiber-fringe formed. Because none of the cultures in the present or past studies have demonstrated a true cementoid matrix, this model may not be suitable for the in-vitro study of cementum formation.