A cytological study of the albuminsecreting cells of the hen oviduct

1. The electron and light microscope have been employed in a cytological study of the albumin-secreting cells of the hen oviduct and of fractions of this tissue obtained after homogenization and differential centrifugation. 2. These studies confirm the observation that in this tissue material corresponding to liver "microsomes" in amino acid-incorporating ability and ribonucleic acid content sediments in relatively low centrifugal fields. 3. The electron microscope studies suggest that the protein secretion of the gland is formed in intimate association with the ergastoplasm.     

Keratin metabolism in the epidermis and hair of mice with experimental diabetes]

An animal trial was performed using mice with streptozotocine-induced diabetes, with investigation of velocity of prekeratin and keratin biosynthesis and degradation using 14C-glycine, and evaluation of the content of -SH and -S-S groups in epidermal prekeratin. It has been found out that velocity of epidermal prekeratin and keratin in diabetic animals is higher than that in healthy group. SS and SH groups ratio in prekeratin in diabetic animals is 10 times as high as that in the control group. In the hair of diabetic mice an increased keratin turnover was observed as compared with the norm. The data testify that experimental diabetes manifests itself in increased intensity of keratin metabolism in epidermis and hair. These results may be used as the criteria in elaboration of non-invasive methods for diabetes diagnosis.     

Histological and cytological study of neoblasts and fixed parenchymal cells in Dendrocoelum lacteum planarians deprived of their anterior region]

On amputating either at the root of the pharynx or between the mouth and the genital pore, the posterior parts which are thereby isolated do not regenerate. However they are capable of surviving for ever a year, without feeding. The wounded region is occupied by neoblasts which degenerate within a few days after an initial secretory activity. Their degeneration is of autophagic type. The abortive blastems disappear only slowly, because the degeneration of their neoblasts is partly compensated by the continual immigration of new regeneration cells which come from the posterior region. Several months after amputation, under the effect of prolonged starvation, neoblasts and fixed parenchymal cells begin to degenerate.     

Sensitivity of inbred mice to toxoplasma of virulent and nonvirulent strains according to parasitological study data]

Genetic peculiarities of mice were studied in regards to their susceptibility to toxoplasms. Differences in susceptibility to little virulent toxoplasms in mice of 9 different lines are shown, which manifest at all stages of the infection process or only at acute or chronic stages. The susceptibility of 6 lines of mice to virulent toxoplasms was found to be equally high.     

Effect of arsenite on the physiological and cytological properties of Pseudomonas putida strains capable of degrading polycyclic aromatic hydrocarbons]

Some physiological and cytological properties of Pseudomonas putida strains resistant to arsenite and capable of degrading polycyclic aromatic hydrocarbons were studied. The resistance of P. putida BS202 (NPL-1) to arsenite proved to be determined by chromosomal genes, while the arsenite resistance of P. putida BS238 (pBS2; pBS3031) was by plasmid-borne genes. Arsenite affected the pattern and rate of growth of strain BS202 (NPL-1) in media with naphthalene or salicylate as carbon sources; particularly, it lengthened the lag phase. Electron-microscope analysis of the strains studied did not reveal any arsenite-induced destructive changes in the cell envelope. At the same time, arsenite in the growth medium induced some alterations in the structure of the outer membrane of strain BS202 (NPL-1) and the cytoplasmic membrane of strain BS238 (pBS2; pBS3031) and, in both strains, led to an increase in the density of intramembrane particles on the EF face of the freeze-fractured cytoplasmic membrane. Arsenite resistance probably evidently protects cells of both strains from greater damage. Physiological and cytological data suggest that the mechanisms of arsenite resistance in the strains studied are different.     

Effects of estrogen on the uterus of mice of different strains]

The strain differences in the response of uterus to the administration of exogenous oestrogen was studied. The uterus of mouse strain CBA appeared to be more susceptible than in strains C57B16 and C3HA, this manifested itself in a lower threshold for development of pseudoestrus and a more pronounced increase of uterine weight.     

Chromosome effect of cyclophosphamide in various strains of mice]

The chromosomes of four different mouse strains were examined after administration of a single dose of cyclophosphamide, 100 mg/kg. Chromosomal breaks and rearrangements were produced in C3H mice three to four times as frequently and in AKR mice twice as frequently as in C57 B1 and XLII Orl mice. This indicates that cytogenetic investigations in mutation research using mice as in vivo test systems may be variable depending on the mouse strain employed. Because the effect of the alkylating agent was not pronounced in the two strains having a high incidence of cancer and leukemia (C3H and AKR), the possibility of a relationship between chromosomal instability and cancer proneness is discussed.     

Intracellular calcium regulation in inner hair cells from neonatal mice

The mechanisms that regulate the concentration of ionized intracellular calcium (Ca(2+)(i)) in the base of neonatal mouse inner hair cells, close to synaptic sites, were investigated using confocal microscopy combined with conventional patch-clamp electrophysiology. Cells were depolarized under whole-cell voltage clamp to load the cell with C a(2+) through voltage-activated Ca(2+) channels. Repeated depolarizations produced Ca(2+)(i) increases with similar amplitudes and time-courses of recovery. The rate of recovery from depolarization-induced Ca(2+)(i) loads was used to assess the mechanisms responsible for Ca(2+)(i) regulation. Removal of extracellular sodium had no effect on resting Ca(2+)(i) or the rate of recovery of Ca(2+)(i) suggesting no role for Na:Ca exchange in these cells. Inhibitors of intracellular store uptake such as thapsigargin, 2,5-di(tert-butyl)hydroquinone (BHQ) and cyclopiazonic acid (CPA) caused an increase in resting Ca(2+)(i) and slowed the rate of recovery, indicating that Ca(2+) can be taken up intracellularly. However, 5mM caffeine failed to cause a detectable release of Ca(2+) from intracellular stores. FCCP, a mitochondrial inhibitor, slowed the rate of recovery from Ca(2+)(i) loads, indicating a role for mitochondrial Ca(2+) uptake. The largest effects were seen with intracellular vanadate (1mM) which caused an irreversible rise in resting Ca(2+)(i) and depolarization-induced increases in Ca(2+)(i) failed to recover fully. Together, these data indicate that both thapsigargin-sensitive stores and mitochondria can take up Ca(2+)(i), but that Ca(2+) efflux from the cell occurs solely via a plasma membrane Ca(2+)-ATPase.     

A cytological study of the capacity for differentiation of normal hemopoietic colony-forming cells

A two-stage procedure has been used to obtain hemopoietic spleen colonies derived from single precursor cells containing radiation-induced chromosomal markers. Of a total of 46 colonies examined, 17 were found to contain cells with abnormal karyotypes. In each of the 17 marked colonies, 90% or more of the dividing cells in the colony carried the same marker. Cell suspensions prepared from each of the individual colonies were tested for their content of dividing cells possessing recognizable differentiated functions. Metaphase cells with peroxidase-positive granules in their cytoplasm were considered to be members of the granulopoietic series, while metaphase cells which contained Fe⁵⁵ were considered to be members of the erythropoietic series. Results were obtained for 12 of the marked colonies, and in nine of these, the percentage of metaphases lacking the marker was less than the percentage of metaphases which were scored as erythropoietic, and also was less than the percentage of metaphases scored as granulopoietic. This is the result which would be expected if the marker were present in both erythropoietic and granulopoietic cells. These results provide support for the view that colony forming hemopoietic stem cells are multipotent, and that differentiation along more than one pathway can occur during the formation of macroscopic splenic colonies.     

Early cytological differentiation in the cerebral hemisphere of mice

Summary 1. The parietal region of the telencephalic vesicle of mice embryos and newborn mice has been studied electronmicroscopically. Special attention has been paid to developing glia cells. 2. In early stages it is impossible to differentiate neuroblasts from glioblasts. 3. Late pre-natal stages allow a recognition of glioblasts on account of their ultrastructure, as the overall structure of the nucleus and the cytoplasm of a glioblast has a greater electron-density than that of a neuroblast. 4. Glioblasts have a lobulated nucleus at this stage (20th day i.u.) while neuroblasts possess an ovoid nucleus. The quantity of endoplasmic reticulum and of the number of ribosomes is relatively greater in neuroblasts than in glioblasts.We gratefully acknowledge the support of the Deutsche Forschungsgemeinschaft (Gl. 28/4) and Stiftung Volkswagenwerk.