Ultrastructure of the water-clear cell in the parathyroid gland of SAMP6 mice

Although the parathyroid water-clear cell is very rare, it has clinical significance because of its association with parathyroid hyperplasia or adenoma. SAMP6, a substrain of senescence-accelerated mouse, was developed as an animal model for senile osteoporosis. We investigated the morphology of the parathyroid glands in SAMP6 and age-matched normal mouse SAMR1. The parathyroid water-clear cells, which contained numerous vacuoles and the crystalloid inclusions, were found in SAMP6 mice at 5, 8 and 12 months of age. It was noted that the number of water-clear cells increased with aging, which are fairly consistent with the change of the serum parathyroid hormone (PTH) level. We did not find any water-clear cells in the parathyroid glands of SAMR1 mice. The existence of water-clear cells may represent hyperfunction of the parathyroid glands in SAMP6.     

Ultrastructural evaluation of the parathyroid glands of young cats with experimental hyperparathyroidism

Summary Kittens with an immature skeleton fed exclusively a calcium-deficient beef heart diet for 1 to 14 weeks developed hypocalcemia, parathyroid hyperplasia, and generalized osteitis fibrosa. Initial ultrastructural changes in the stimulated parathyroid glands were observed after 1 week and consisted of increased cytoplasmic volume, aggregation of the granular endoplasmic reticulum, and enlargement of the Golgi apparatus associated with increased numbers of prosecretory granules. After 3 weeks, chief cell hyperplasia was first observed and the numbers of mature secretory granules were greatly reduced. The hyperactive chief cells remained degranulated until the termination of the experiment. Stimulated chief cells accumulated glycogen in excess of controls and contiguous chief cells had intricately interdigitated plasma membranes. The parathyroid glands of experimental cats after being fed the low calcium diet for 14 weeks contained primarily hyperactive and vacuolated light chief cells with an occasional transitional water-clear cell.This investigation was supported in part by the Morris Foundation and grant GM 1052, National Institutes of Health, United States Public Health Service. The authors wish to acknowledge the technical assistance of Mr. D. Q. Davis and Mr. O. R. Kindig.     

Removal of Plant Nutrients by Means of Aerobic Stabilization of Sludge

In the conventional treatment of sewage, the solids are normally disposed of by anaerobic digestion. This leaves a considerable amount of plant nutrients, such as nitrogen and phosphate, as soluble compounds which will eventually find their way into the plant's final effluent, since the supernatant fluid from the digesters is normally returned to the raw sewage. In a recent investigation, we found that, if the sludges were treated by an aerobic process, a significant portion of the carbonaceous matter was oxidized to carbon dioxide and water, and the rest was assimilated into microbial protoplasm. This process tied up the available nitrogen and phosphorus so that practically none remained dissolved in the suspending liquid. The accumulated solids, consisting mostly of microbial cells, were separated very easily from the liquid, leaving a slightly colored supernatant fluid that was water-clear, free from plant nutrients, and very low in BOD and COD. The overall process was accomplished in a detention time not exceeding 20 days, in contrast to anaerobic digestion which requires from 50 to 70 days.     

Thiosulfate-Schiff Reagent

Na₂S₂O₃ and HCl can be used as the reducing system to make Schiff reagent, the sulfur produced by the reaction acting as the adsorbent and consequently eliminating the need of decolorizing charcoal. To 100 ml of a 0.02% solution of basic fuchsin add 8 gm of dry Na₂S₂O₃ shake for 3 min, add 0.5 ml of cone. HCl (final concentration 0.05 N). Do not heat. Store in a refrigerator (4° C) overnight, and filter. The filtrate is water-clear, and will remain stable for 24 hr at room temperature. Periodic acid-Schiff and Feulgen reactions can now be performed, preferably at refrigerator temperature, although the times required are notably prolonged (6-8 hr). Background color is slight, and specificity good.     

Measurement of oxalate in human plasma ultrafiltrate by ion chromatography

An improved ion chromatographic method for the measurement of oxalate in human plasma ultrafiltrate is described. Ultrafiltration was carried out using an appropriate device and procedure. Centrifugation of 0.5 ml heparin plasma at 4°C for 50 min yielded water-clear ultrafiltrate in amounts allowing replicate measurements of oxalate. The specificity of the method was confirmed. The recovery of oxalate added to plasma was approximately 80%, whereas dilution of plasma, and of an oxalate-containing salt solution, resulted in falsely high values; the mechanism(s) underlying this phenomenon are insufficiently understood at present. The intra-assay of the method was assessed and from replicates of a pool plasma, the inter-assay precision from ten measurements of the same plasma on different days; the observed ranges of oxalate were 1.32-1.56 (mean 1.42) and 1.42-1.64 (mean 1.53) μmol/l, respectively. In plasma ultrafiltrate of a limited number of healthy volunteers the range of oxalate was 1.81-2.50 μmol/l, thus permitting renal oxalate handling to be studied.     

ELECTRON MICROSCOPE OBSERVATIONS ON MYOSIN FROM PHYSARUM POLYCEPHALUM

Myosin has been separated from Physarum polycephalum actomyosin in confirmation of the results of Hatano and Tazawa. In an intermediate step, myosin-enriched actomyosin has also been obtained. The mean yield of free myosin was 4.4 mg from 100 g of mold. It was obtained as water-clear solutions at µ = 0.055 with calcium ATPase activity of up to 0.5 µM P_i/min per mg. Negatively stained preparations were examined by electron microscopy. Physarum myosin in 0.5 M KCl interacted with actin from rabbit skeletal muscle to form polarized arrowhead complexes similar to but less regular than those of natural actomyosin from muscle or myosin-enriched Physarum actomyosin. The Physarum myosin-enriched actomyosin at low ionic strength displayed evidence of head-to-tail and tail-to-tail aggregation attributable to the myosin component. Yet Physarum myosin alone did not produce detectable filaments at µ = 0.055 at pH 7, 6.5, or 5.8, nor when dialyzed against 0.01 M ammonium acetate, nor when the dielectric constant of the medium was reduced. However, aggregation approaching the extent of ‘thick filaments’ up to 0.3 µ long was found in some preparations of myosin-enriched actomyosin put into solutions containing adenosine triphosphate. Myosin alone in such solutions did not form filaments. The results are compatible with the idea that head-to-tail aggregations are favored by actin-myosin interactions in Physarum, possibly due to alignment of the extended or tail portions of this myosin molecule.     

Development of the mammalian gonad: the fate of the supporting cell lineage

Sex determination in mammals is mediated via the supporting cell lineage in the fetal gonad. In the very early stages of gonadal development, the fate of the supporting cell population is critically dependent on the expression of the male-determining gene on the Y chromosome. If this gene is absent or fails to be expressed, or is expressed too late or in too small a number of supporting cells, all supporting cells (XX or XY) differentiate as pre-follicle cells and development proceeds along the female pathway. Supporting cells in which the male-determining gene is expressed in a timely manner differentiate as pre-Sertoli cells; given sufficient such cells, testis cords form and development proceeds in a male direction. If XX supporting cells are also present, a few may be recruited into the pre-Sertoli population and participate in testis cord formation. The subsequent fate of pre-follicle cells depends critically on interaction with the germ cell population in the developing gonad: absence of germ cells may lead to partial masculinization of the gonad, and/or to disappearance of the supporting cell component.     

Observations on the histology and histochemistry of the oesophagus of the perch, Perca fluviatilis L.

The anatomy and enzyme histœhemistry of the œsophagus of a freshwater teleost perch ( Perca fluviatilis L.) has been studied. The mucosa is composed of an undifferentiated layer of basal epithelial cells, mucous cells and surface epithelial cells. The submucosa is compact and contains blood vessels, nerves and bundles of striated longitudinal muscles. The outer circular muscular layer contains both striated and smooth muscle fibres. Electron microscopy shows that the surface epithelial cells are degenerative and that they surround and support pores of the mucous cells. Undifferentiated epithelial cells undergo cytoplasmic changes and eventually become surface epithelial cells. Mucous cells arise from the undifferentiated epithelial cells and their droplets contain acid and neutral mucosubstances. Alkaline phosphatase, non-specific carboxylic esterases and aminopeptidase activity is absent in the mucosa. However, acid phosphatase activity is localized in the surface epithelial cells.     

Demonstration of the heterogeneity of the mast cell population on the basis of the mucopolysaccharide content.

From the aspect of its mucopolysaccharide content the mast cell population is not homogeneous. The pulmonary and heart muscle mast cells of the rat are alcian blue positive, the mast cells of the thyroid gland, lymph nodes, subcutaneous connective tissue, mesentery and peripheral nerve are safranin positive, whereas among the mast cells of the peritoneal cavity and the thymus there are both alcian blue and saffranin positive forms. The least acid mucopolysaccharides are in the mast cells of the peritoneal fluid, the mesentery and the lungs, whereas the most acid ones are in the mast cells of the lymph nodes, the subcutaneous connective tissue and the thyroid gland. There is a considerable difference between the two last mentioned organs. The mast cells of the subcutaneous connective tissue are end-product cells without amine or precursor turnover, whereas the mast cells of the thyroid gland incorporate and deliver amines, which may participate in the regulation of the host gland.     

Endocrine cells of the mucous membrane of the fundus region of the stomach of hibernating rodents]

The gastric mucous membrane was studied in the hibernating animal Citellus erythrogenys in different seasons (during 7-8 months a year the animal is in hibernation and its digestive tract is not functioning). During hibernation the general amount of enterochromaffin-like cells decreases and their composition changes: the number of active cells diminishes and that of less active cells grows. Such dynamics of cells suggests the participation of enterochromaffin-like cells of Citellus erythrogenys in the regulation of gastric secretion (in rats and mice these cells contain histamine stimulating the mucous membrane glands). The amount of true enterochromaffin cells is not sufficiently changed and they seem to be not directly related with digestion but to be producers of serotonin which (together with serotonin of the brain) takes part in sustaining the mechanisms of appearance and supporting of winter hibernation.     

A morphologic study of the ductus of the epididymis of Sus domesticus

The head, body, and tail regions of the epididymal duct (or caput, corpus, and cauda epididymis) in two healthy and sexually mature Sus domesticus males were examined by light microscopy and by scanning or transmission electron microscopy. The epididymal duct is lined with a pseudostratified epithelium with stereocilia and covered by a muscular-connective tissue sheath that is thickest in the tail region. Diameter of the epididymal duct and height of epididymal epithelium are maximal in the head region. Length of the sterocilia and spermatic density are higher in the head and body regions. Somatic cells are abundant in the tail region. The epididymal epithelium is made up of five cell types: basal cells, principal cells, clear cells, narrow cells, and basophilic cells. Abundant secretory units are observed in the supranuclear cytoplasm of columnar principal cells. Each mature secretory unit is constituted by electron-dense secretion granules covered by more than eight layers of cisternae of reticulum between which the mitochondria are intercalated. In the apical cytoplasm the isolated secretion granules become larger and less electron dense. The apical surface is covered by numerous sterocilia. Basal cells are pyramidal and less high than principal cells. The clear cells, arranged between the principal cells, are characterized by the presence of abundant vesicular elements and electron-lucid secretion granules, and by an apocrine secretory process. The narrow cells are characterized by their highly vacuolized cytoplasm. Intermediate cell typologies can be found among basal, principal, clear, and narrow cells, which could be four developmental stages of the same cell type. The basophilic cells are spheroidal and are found at different levels between the epithelial cells and in the connective tissue underlying the epithelium. © 1993 Wiley-Liss, Inc.     

Ultrastructure of the tegmentum vasculosum of the chicken cochlea

Ultrastructural studies have been made on the dark and light cells, as well as on their interconnections with capillaries in the tegmentum vasculosum of the chick cochlea. The dark cells exhibit ultrastructural peculiarities which are typical for ion transporting cells: their lower part is presented by a system of numerous cytoplasmic projections filled with mitochondria. The role of the light cells is less evident. It is suggested that they may control the exchange of ions and other metabolites between the dark cells and capillaries. Significant ultrastructural differences are described between the tegmentum vasculosum in chicks and the stria vascularis in mammals.     

The electron microscopy of the left colleterial gland of the cockroach

A study has been made of the cells of the left colleterial gland of the cockroach, Periplaneta americana (L.), using the electron microscope, and the results compared with previous histological and histochemical studies. The colleterial gland consists of an arborescent bunch of long tubules composed mainly of the cells which secrete the structural protein of the egg case ("type 4 cells"). Other types of cells: chitinogenic cells and "type 2 and 3 cells" each with a different cytology are described. The type 4 cells, which form the structural protein, reveal a cytological pattern very similar to that described for mammalian cells in a state of active protein synthesis. There is an elaborate development of particle-studded membranes in the cytoplasm. Smaller, rounded agranular vesicles also occur. The free secretory surface of the secreting cells forms the "end-apparatus" of the light microscopists. The invaginated surface is cast into numerous long narrow processes usually radially arranged and directed into a funnel-like formation derived from the thin intima lining the lumen of the gland (Text-fig. 2). The secretion in the form of small balls may be seen in the cavity of the end-apparatus and sometimes in the narrow processes. The small chitinogenic cells, lying between the protein-forming cells and the thin intima which they secrete, have a different cytology perhaps related to the fact that they form a polysaccharide rather than a protein. There is a very poor development of the particle-studded membranes of the type found in protein-forming cells. The type 2 cells, supposed to form an oxidase, have an end-apparatus that is similar to, but more complex than, those of the type 4 cells and their cytoplasm is almost completely filled with mitochondria. There is some evidence that mitochondria play a part in forming the oxidase and pass into the tubules of the end-apparatus. Type 3 cells resemble both types 2 and 4 and are probably a transient intermediate form.     

On the nature of the tumor-initiating cell

Certain aspects of tumors that may influence areas of basic biology and medicine are reviewed. The hypothesis that malignant stem cells evolve from normal stem cells, is considered. Information is being accumulated on the possibility that certain cell populations that can be propagated as cell lines in vitro can produce cells with features of differentiated cells in addition to others that maintain the line and, in some cases may also initiate tumor formation in vivo. Up to the present time, there is evidence to show that cancer stem cells persist in many cell lines. Tyrosine kinase inhibition produces combinations of autophagy and apoptosis in the human erythroleukemia cell line TF-1 hinting at a heterotypic aggregation of cells containing cancer stem cells. Finally, the mechanisms of cancer development, invasion and metastasis are operatively defined. The purpose of this paper is to review some of the salient features of cancer stem cells in support of the proposal that research in neoplasia be increased. Rather than presenting details of various studies, we have attempted to indicate general areas in which work has been done or is in progress. It is hoped that this survey of the subject will demonstrate a variety of opportunities for additional research in human neoplasia.     

Investigation of the nature of electrical responses of horizontal cells of the fish retina

On the basis of the syncytial structure of the layer of horizontal cells of the fish retina, a method is developed which effectively shifts the membrane potential of cells by means of an electrical current. It is shown that the response of L-type horizontal cells to light and electrical stimulation of the retina is reversed when the membrane of the horizontal cells is depolarized by a direct current. The equilibrium potential of the cells was near the zero level. Consequently, the depolarization response of the horizontal cells to disconnection of the light and to electrical stimulation of the retina is an excitatory postsynaptic potential, whereas hyperpolarization of the horizontal cells to light is a decrease of this potential. It is shown that the membrane of fish horizontal cells have pronounced nonlinear properties: in the case of strong depolarization and especially in the case of hyperpolarization its impedance drops markedly. The latter probably occurs due to an increase of the permeability of the nonsynaptic membrane of the horizintal cells for K⁺. This can also explain the decrease of membrane impedance during the hyperpolarization response of the horizontal cells to bright light. The available data indicate the presence of regenerative properties of the membrane of horizontal cells.Institute of Problems of Information Transmission, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 3, No. 1, pp. 89–98, January–February, 1971.     

Variations in the Size of Mitotic Cells in the Root Meristem

Variations in the length of mitotic and interphase cells were analyzed in various tissues of wheat roots and in the cortex of maize roots. Reliable differences were shown in the length of mitotic cells in individual file clones of cells of the same tissue. The mean lengths of dividing cells in different roots differed to a lesser extent than those of different files in the same tissue of one root. Within the file, the length of the sister simultaneously dividing cells differed the least, while the difference of lengths of the neighbor simultaneously dividing nonsister cells was bigger. The mean length of interphase cells in any file was always less than that of mitotic cells by a factor of 1.45. This ratio was almost invariable for files and tissues in both the plants we studied and corresponded to that of an exponentially growing cell population. In addition, a very small number of cells were found (less than 1%) in meristems, which are longer than the mitotic cells. The length of these cells exceeded those of mitotic cells by less than twice. The origin of such cells is discussed. The length of mitotic cells near the quiescent center is more variable than in the middle of the meristem in the cortex of both plants. In the meristem basal part, the mitotic cells were no longer than those in the middle of the meristem but there were no small dividing cells. In the wheat epidermis, the cells are differentiated into trichoblasts and atrichoblasts and, therefore, the length of the dividing cells is highly variable. The cell length is essential for their transition to mitosis for all studied proliferating meristem cells.     

The Electron Microscopy of the Left Colleterial Gland of the Cockroach

A study has been made of the cells of the left colleterial gland of the cockroach, Periplaneta americana (L.), using the electron microscope, and the results compared with previous histological and histochemical studies. The colleterial gland consists of an arborescent bunch of long tubules composed mainly of the cells which secrete the structural protein of the egg case ("type 4 cells"). Other types of cells: chitinogenic cells and "type 2 and 3 cells" each with a different cytology are described. The type 4 cells, which form the structural protein, reveal a cytological pattern very similar to that described for mammalian cells in a state of active protein synthesis. There is an elaborate development of particle-studded membranes in the cytoplasm. Smaller, rounded agranular vesicles also occur. The free secretory surface of the secreting cells forms the "end-apparatus" of the light microscopists. The invaginated surface is cast into numerous long narrow processes usually radially arranged and directed into a funnel-like formation derived from the thin intima lining the lumen of the gland (Text-fig. 2). The secretion in the form of small balls may be seen in the cavity of the end-apparatus and sometimes in the narrow processes. The small chitinogenic cells, lying between the protein-forming cells and the thin intima which they secrete, have a different cytology perhaps related to the fact that they form a polysaccharide rather than a protein. There is a very poor development of the particle-studded membranes of the type found in protein-forming cells. The type 2 cells, supposed to form an oxidase, have an end-apparatus that is similar to, but more complex than, those of the type 4 cells and their cytoplasm is almost completely filled with mitochondria. There is some evidence that mitochondria play a part in forming the oxidase and pass into the tubules of the end-apparatus. Type 3 cells resemble both types 2 and 4 and are probably a transient intermediate form.     

Cytophotometric analysis of the cell population composition of the the preoptic area of the hypothalamus in the common frog

DNA contents in squashed cells of the adult frog hypothalamic preoptic region (HPR) were measured using the Feulgen and UV cytophotometry techniques. The histone-DNA ratio in the cell nucleus was determined by means of a combined Feulgen-heparin-Alcian blue staining procedure. The nuclei of the vast majority of HPR cells have a diploid DNA content. However, in cells of this group the mean values of DNA amount and the distribution range were always higher than those in hepatocytes used as a diploid standard. Such a heterogeneity in DNA content in the diploid part of HPR cell population could apparently suggest some differences in the nuclear chromatin arrangement to be always higher in spring before the frog spawning, and it seems to be characteristic of this type of cells. About 1 per cent of cells with hyperdiploid surplus of DNA (H2c cells) as well as of tetraploid cells (4c and 2c X 2 cells) is found in HPR in frogs sacrificed both in winter and in summer. The quota of these cells has no reference either to the frog's age or to the annual cycle. The fact that the mean DNA values in H2c and 4c cells are much higher than in the standard cannot be explained by the presence of different amounts of nuclear proteins only. It is suggested that at least some part of the highest DNA values may be due to an actual extra DNA synthesis in a small constantly existing pool of HPR cell population.     

Structure of the ovary and the differentiation of follicular epithelium in the pig louse, Haematopinus suis (Insecta: Phthiraptera)

The female reproductive system of the pig louse, Haematopinus suis (Insecta: Phthiraptera) is composed of paired ovaries, lateral oviducts, and a common oviduct that leads into a vagina. Clusters of mycetocytes (= cells filled with symbiotic organisms) are associated with lateral oviducts. Each ovary is composed of five loosely arranged ovarioles of the polytrophic-meroistic type. An individual ovariole is covered by a basal lamina and is composed of a terminal filament, germarium, and vitellarium. The terminal filament is composed of large, disc-shaped cells that are orientated perpendicularly to the long axis ofthe ovariole. The basal part of the terminal filament is separated from the germarium by a well-developed transverse septum. The germarium is short and filled with clusters of oogonial cells. In each cluster the cells arejoined by intercellular bridges, filled with fusomal material. Within the cluster, only one cell, the future oocyte, enters the prophase of the first meiotic division; the other cells differentiate into nurse cells. The basal part ofthe germarium is filled with the somatic prefollicular cells. The boundary between the germarium and the vitellarium is not distinct. The vitellarium contains linearly arranged ovarian follicles in subsequent stages of oogenesis (previtellogenesis, vitellogenesis and choriogenesis). Each follicle consists of an oocyte and 7 nurse cells and is surrounded by follicular cells. During oogenesis the follicular cells diversify, so that ultimately, five morphologically distinct subpopulations of these cells can be distinguished: (1) cells in contact with the nurse cells, (2) anterior cells, (3) mainbody cells, (4) posterior cells, and (5) interfollicular cells. Interestingly, the follicular cells associated with the anterior part of the oocyte, i.e. located in space at the oocyte/nurse cell border (fold cells) are mitotically active throughout previtellogenesis. It might be suggested, in this context, that the separation of the oocyte from the nurse cell compartment is brought about by mitotic divisions, consequent multiplication and centripetal migration of these cells.     

The fine structure of the newly discovered propodial ganglia of the veliger larva of the nudibranch Onchidoris bilamellata

Summary Two pairs of ganglia are found in the propodial region of the veliger of Onchidoris bilamellata: the anterolateral pair is located at the foremost corners of the propodium, and the frontal pair is located beside the propodial midline. Both sets of ganglia are positioned below the epidermis, and they are joined to the cerebral ganglia by large, common connectives. Each ganglion possesses sensory cells, nerve cells and sheath cells, and the frontal pair contains a complement of secretory cells. Externally, the propodial ganglia are manifested as sensory fields. The fields of the anterolateral pair are elliptical in shape, and each appears as a band of cilia bordering an unciliated zone. The region devoid of cilia is composed of ordinary epidermal cells, whereas the ciliated portion is comprised of dendritic endings originating from cells in the ganglion. Dendrites arise from one type of sensory cell and pass through the epidermis in bundles. Each dendrite terminates as a single cilium at the epidermal surface. Sensory fields of the frontal ganglia are key-shaped and oppose one another on the anterior end of the foot. Each field appears as a flat, circular, unciliated region which extends into a ciliated groove that runs dorsally toward the mouth. The groove contains the terminals of secretory cells, ciliated sensory cells, and the cell bodies of nonciliated sensory cells. The nonciliated sensory cells, characterized by a microvillous apex, are the dominant cells in the flattened circular zone. The space between the frontal ganglia and the epidermis is bridged by bundles of processes which are similar to those of the anterolateral ganglia. However, these tracts contain collections of the apical processes of secretory cells, the dendrites of ciliated sensory cells, and the axons of nonciliated sensory cells. Morphological and behavioral evidence indicates that the propodial ganglia serve a chemosensory function during settlement and metamorphosis.