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Biomedical subjects

T B Pool

Publications and source records attributed to T B Pool.

33 records · Page 2Linked to original sources
PubMed1981

Elemental content in the nucleus and in yolk and yolk-free cytoplasm of developing Rana pipiens oocytes: an x-ray microanalysis study.

Energy dispersive x-ray microanalysis measured the Na, K, Cl, P, Mg, S, and Ca contents (mM/kg dry weight) in the nucleus, yolk-free cytoplasm, and yolk platelets of Rana pipiens oocytes quick frozen in the ovary. The data revealed that significant content changes occur in frog oocytes during intraovarian growth. All elements but Ca changed in content in the nucleus and cytoplasm, while in the yolk platelet only Na content did not change. A nucleus to cytoplasm K gradient develops and increases in magnitude during oocyte growth. The data from this and previous reports lead to the hypothesis that intra-oocytic water and elements undergo changes in state during oocyte growth and that three subcellular Na compartments exist.

Animals↗
PubMed1980

Intracellular concentration of potassium and other elements in vaginal epithelial cells stimulated by estradiol administration.

Electron probe x-ray microanalysis was used to measure cytoplasmic elemental content (in mmoles/kg dry weight) of the basal layer of cells of the vaginal epithelium of ovariectomized rats. Measurements were made both before estradiol injection and at 2 hr, 17 hr, and 24 hr after estradiol administration. Mitotic figures first appeared in the basal cell layer at 24 hr. During the course of the study significant time-dependent differences were seen in the content of all elements mesured. A pattern of change in cytoplasmic content was seen for Na, P, S, and Cl; all of which decrease significantly by 17 hr and then return to approximately the nonstimulated concentration by 24 hr. On the other hand K, and to a lesser extent Mg, show an early and continued increase in cytoplasmic content after estadiol injection. Thus, the marked increase in the intracytoplasmic content of K in the estradiol treated cells suggests that K, or the ratio of Na to K, may be directly or indirectly involved in growth stimulation.

Animals↗
PubMed1980

Changes in proliferation and surface morphology in the rat ileum in response to total parenteral nutrition.

To find out how the ileum adapts to total parenteral feeding, two experiments were performed. In the first experiment rats were given total intravenous feeding for 10 days. The animals were injected with tritiated thymidine (1 muCi/g body weight) 1 hour before being killed. Portions of the ileum were used for (1) radioautography, (2) analysis of the tissue DNA content, (3) specific activity of the DNA, and (4) scanning electron microscopy. The DNA content of ileum was decreased 72% while the specific activity of DNA was increased 289% in the i.v. fed rats. In the second experiment rats were given total intravenous feeding for 10 days. The animal were injected with colchicine (1 mg/kg body weight) 3 hours before being killed. The number of labelled cell nuclei per ileal crypt section was significantly decreased by parenteral feeding as was the number of colchicine collected metaphase figures. Light microscopy revealed the crypt and the villus height to be shorter and the number of goblet cells per unit surface area to be increased in parenterally fed rats as compared to those fed solid food orally. Enterocytes of the exfoliative zone from the ileal villi of rats fed solid food showed three distinct types of surface architecture whereas those from i.v. fed rats all possessed abundant microvilli. No bacteria were seen in ilea of i.v. fed animals but many were seen embedded in enterocytes from orally fed rats. Because the amount of DNA per cell is known to be constant, we concluded that the overall number of cells in the lieum decreased about 72% in the i.v. fed rats and that cell proliferation in the crypts, although significantly deceased, was still supporting an epithelial renewal process.

Animals↗
PubMed1980

Evaluation of a preparative method for x-ray microanalysis of soft tissues.

We have adapted the cryopreparative methods designed for the radioautography of diffusible substances (Stumpf and Roth, 1966, 1967) to produce freeze-fried sections of soft tissues for electron probe microanalysis. This report concerns the evaluation of these methods for use with X-ray microanalysis with particular reference to: (1) the preservation of cellular morphology, (2) the introduction of structural artefact by ice crystal formation, (3) the preservation of natural elemental distributions under experimental conditions where known quantities of diffusible elements are present, (4) the effects of ice crystal formation upon possible artefactual elemental redistributions, (5) the effect of section thickness on elemental quantitation, and (6) the effect of tissue excision on element translocation. Freeze-dried sections were prepared from mouse pancreas and from 20% (w/v) solutions of bovine serum albumin (BSA) and gelatin containing known amounts of inorganic salts and were analysed in a scanning electron microscope fitted with energy dispersive X-ray detecting equipment. With the preparative methods used, the morphology of pancreatic acinar cells was well preserved. Acinar cell boundaries, nuclear boundaries, chromatin, nucleoli, ergastoplasm and zymogen granules were readily discernible. Ice crystals were present within sections of BSA, but 70% had a cut surface area < 1 micrometer2 and over 90% had a cut surface area of < 2 micrometer2. Characteristic peak-to-continuum ratios of elements in the BSA sections remained constant over an order of magnitude change in magnification. Elemental redistributions were not detected until the magnification was such that the analysed area fell totally within the confines of a single ice crystal. No differences in elemental peak-to-continuum values were obtained between 2 and 4 micrometer sections of the gelatin-salt solution. Tissue excision did not cause element translocations when compared to tissues frozen in situ. We conclude that this method is valid for preparing tissues for microanalysis under our conditions (analysis of nuclear, cytoplasmic, and secretory compartments) and is limiting only when analyses are conducted at very high magnifications.

Animals↗
PubMed1979

An X-ray microanalysis survey of the concentration of elements in the cytoplasm of different mammalian cell types.

Electron probe energy dispersive X-ray microanalysis was performed on freeze-dried tissue sections. The dry weight concentration of elements (mmole/kg dry weight) was measured in the cytoplasm of several cell types from adult mice and rats. This comparative investigation showed: (1) That the energy dispersive X-ray spectrum of element concentration from the cytoplasm of a specific cell type allows one to distinguish this specific cell type from other cell types with considerable accuracy. (2) That there is a relationship between the concentration of the various elements and the ultrastructural features of the cytoplasmic regions being analyzed. For example, areas rich in ribosomes are also rich in P, K and Mg. (3) These data support the idea that K is directly involved in the control of protein synthesis. The catalog of element concentrations in the cytoplasm of 13 cell types from both mice and rats should be of value to others who seek to answer various questions about these cell types.

Animals↗
PubMed1979

Element concentration changes in mitotically active and postmitotic enterocytes. An x-ray microanalysis study.

Unfixed freeze-dried and uncoated tissue sections of the mouse duodenum were suspended across a hole in a carbon planchet and analyzed in a scanning electron microscope fitted with energy-dispersive x-ray analytical equipment. Computer analysis of the x-ray spectra allowed elemental microanalysis of the nucleus, cytoplasm, and late anaphase-early telophase chromatin regions in the cryptal and villus enterocytes. Elemental concentrations (mmol/kg dry wt) were measured for Na, Mg, P, S, Cl, K, and Ca. None of the elements were compartmentalized preferentially in either the nucleus or the cytoplasm of interphase enterocytes of crypts or in postmitotic enterocytes of villi. In contrast, Ca, S, and Cl are detectable in significantly higher concentrations in mitotic chromatin of dividing enterocytes of the crypt as compared to surrounding mitotic cytoplasm, but Na, Mg, and P are in lower concentrations in the mitotic chromatin as compared to mitotic cytoplasm. Interphase enterocytes of crypts have higher concentrations of Mg, P, and K, and lower concentrations of Na than do postmitotic enterocytes of villi.

Animals↗
PubMed1978

Relationship between functional castration and alpha-fetoprotein produced by hepatoma-bearing female rats.

In rats bearing Morris hepatoma No. 7777, serum levels of alpha fetoprotein (AFP) increased as tumour size increased. Hepatoma-bearing females remained in dioestrus once the tumour exceeded a cross-sectional area of 12 cm2. The following changes were seen in tumour-bearing rats compared to control animals: uterine wet weight was significantly decreased, the uterine epithelial mucosa was lower, castration cells developed in the anterior pituitary, and there was a 3- to 23-fold elevation in serum oestrogen levels. We conclude that circulating oestrogen is bound to AFP in hepatoma-bearing female rats and that in this bound state it is unable to exert its normal physiological actions.

Animals↗
PubMed1977

Chromatin fibre differences between condensed and dispersed chromatin: a comparative ultrastructure study.

Cells of different types from different species were investigated to determine if there are significant variations between chromatin fibre measurements in electron micrographs of thin sections. A larger chromatin fibre of 20 plus nm is seen in both condensed chromatin and dispersed chromatin and contains an irregularly folded or coiled fibril of 2.1 to 3.7 nm. In all cell types the larger fibre of dispersed chromatin was significantly thicker than the larger fibre of condensed chromatin. Numerous significant differences were also found between chromatin measurements of the different species. The ultrastructural differences may help explain the functional differences already known to exist between dispersed and condensed chromatin.

Animals↗
PubMed1975

Intranuclear and cytoplasmic annulate lamellae in grasshopper spermatocytes (genus Melanoplus).

Intranuclear and cytoplasmic annulate lamellae were studied in grasshopper spermatocytes (Melanoplus) with the electron microscope. Although cytoplasmic annulate lamellae were observed in all three species examined, intranuclear annulate lamellae were found in only one species. The intranuclear annulate lamellae encompass certain nuclear material adjacent to the nuclear envelope forming a vesicle that is extruded into the spermatocyte cytoplasm. In this same species, cytoplasmic annulate lamellae are seen contiguous with granular masses of varying size. These structures were noted as being morphologically indistinguishable from the "yolk nuclei" of dragonfly oocytes (Kessel and Beams, 1969; Kessel, 1973).

Animals↗