Search PubMed⌕ Search

Biomedical subjects

C Pilgrim

Publications and source records attributed to C Pilgrim.

At least 109 records · Page 6Linked to original sources
PubMed1984

Cell proliferation in the dog (beagle) ovary during proestrus and early estrus.

Cell proliferation in the ovaries of 5 Beagle dogs was studied by autoradiography after pulse labelling with (3H)-thymidine during different periods of proestrus and early estrus. Indices of labelling and of necrosis were determined for different follicle types grouped according to their stages of atresia. Cell proliferation became most obvious during early proestrus in antral and in Graafian follicles, and during the periovulatory period in preantral follicles. By contrast, low labelling indices appeared in all follicle types during the middle of proestrus. All follicle types demonstrated a continuous decrease in labelling from early to late atresia with the exception of the granulosal layer of antral follicles during the periovulatory period. While many necrotic granulosal cells were found in antral follicles during the first 6 days of proestrus, there were few during the periovulatory period. Even Graafian follicles displayed necrotic granulosal cells now and then. It may be concluded that (1) intact ovarian follicles can show subtle changes indicating the beginning of atresia, and (2) during the proliferative phase of a long estrous cycle cell replication in the ovary is characterized by two bursts at the beginning and at the end of this period.

Animals↗
PubMed1984

Cell proliferation in the principal target organs of the dog (beagle) ovary during various periods of the estrous cycle.

Cell proliferation in the principal target organs of the ovary was studied in 7 beagle dogs during proestrus, early estrus, secretory and regressive metestrus. Pulse labelling with (3H)-thymidine and autoradiography were applied and labelling indices were determined. Organs with squamous and with glandular epithelium except the mammary gland showed a proliferation peak during early proestrus, the incidence of labelling being higher in organs with squamous epithelium. During early proestrus the intensity of labelling decreased in organs with squamous epithelium in the following order: vulva, vagina, portio vaginalis, and portio supravaginalis. At this time cell replication was higher in the superficial glands of the cervix and corpus uteri as well as the circular layer of the myometrium compared with values from the basal glands or the longitudinal layer. The steepest decline of the proliferative activity occurred between the proestrous period. While some labelled cells were observed during secretory metestrus, labelling was almost absent during regressive metestrus. By contrast, the mammary gland began to develop at the periovulatory period and was at the height of its proliferative activity during secretory metestrus. It is concluded for species with a long estrous cycle that: (1) the rate of cell replication in the vulva, vagina, uterus and oviduct is at its peak at the beginning of the estrous cycle and declines during proestrus; (2) as compared to observations in species with short estrous cycles, cell proliferation is very low during metestrus.

Animals↗
PubMed1983

GABAergic neurons in dissociated cultures of rat hypothalamus, septum, and midbrain.

Cultures of dissociated tissue blocks from 18 day-old rat embryos containing either septum plus anterior hypothalamus, retrochiasmatic hypothalamus, or midbrain, were maintained for 8-29 days in vitro. GABAergic neurons were visualized by incubation with (3H) gamma-aminobutyric acid followed by autoradiography and by immunocytochemistry using an antiserum against glutamic acid decarboxylase. Positive neurons were of variable shapes and sizes. Labeled neurons in the three cultured regions represented 3.4, 1.1 and 1.7%, respectively, of all neurons. Apart from a few exceptions, autoradiographic labeling and immunocytochemical staining coincided. Glial cells did not stain and showed very low grain densities. Radioactivity could be released from preloaded cultures upon depolarization by 50 mM potassium and 100 microM Veratridine. The demonstration of GABAergic neurons in cultures that are known to contain a variety of peptidergic neurons opens up the possibility of studying the interaction between the two classes of neurons in vitro.

Animals↗
PubMed1983

Macrophages and interdigitating cells; their relationship to migrating lymphocytes in the white pulp of rat spleen.

The pathway of lymphocyte migration through the white pulp of rat spleen and the relationship of migrating cells to the accessory cells (marginal zone macrophages and interdigitating cells, IDCs) of the white pulp compartments were analysed. Donor lymphocytes were obtained from lymph nodes, enriched for T lymphocytes and labeled in vitro with 5-(3H)uridine. They were injected intravenously into syngeneic recipients from which samples of spleen were taken at short intervals from 3 to 300 min after injection. Autoradiographs of semithin and ultrathin sections showed that, in the internal layer of the marginal zone (MZ), lymphocytes tended to accumulate within some regions in close proximity to marginal-zone macrophages before migrating into the periarteriolar lymphoid sheath (PALS). The lymphocytes enter PALS between protrusions of the accessory cells located in the peripheral area of the sheath. During migration towards the central area of PALS, a close contact between both cell types was noted. In the central area of PALS, preferential accumulation of lymphocytes around IDCs was observed. Labeled lymphocyte distribution within PALS and the rate of cell migration through the white pulp seem to depend on lymphocyte-IDC contact. A common feature of accessory cells which may affect the migration of lymphocytes in both MZ and PALS is the presence of Birbeck granules.

Animals↗
PubMed1983

Permeability of the external glial limiting membrane of rat parietal cortex.

As the relevance of previous reports demonstrating the permeability of the glia limitans appears to be not generally accepted, the problem is reinvestigated by examination of the ultrastructure of the glia limitans in combination with tracer studies using Ruthenium Red. The results clearly show that gap junctions are the only type of intercellular contact present in this layer. Measurements of the lengths of cross-sections of junctional regions reveal a decrease in size in absolute terms as well as in relation to total astrocytic surface if one proceeds from the more superficial layers into the depth of the tissue. The intercellular clefts leading from the subarachnoidal space into the interspaces of brain tissue are patent thus allowing the tracer to penetrate to a depth of 0.4-0.6 mm in one hour. Although these observations confirm the idea of an ultimate communication between the cerebrospinal fluid compartments and the extracellular space of brain the discussion shows how the particular arrangement of the intercellular channels and the cells bordering them may be suited to control the local composition of interstitial fluid independently from that of the cerebrospinal fluid.

Animals↗
PubMed1982

Volume densities and specific surfaces of neuronal and glial tissue elements in the rat supraoptic nucleus.

The present study was undertaken to provide an explanation for previous autoradiographic results suggesting a several times higher rate of synthesis of glycoconjugates per unit volume of hypothalamic glia than of neurons. Volume densities, specific surfaces (surface-volume ratios), and relative surfaces (contribution of the surface of a tissue element to the total surface of the tissue) were assessed. Neuronal elements occupy about 74% and glial elements about 8% of the total volume. The specific surface, i.e., the amount of plasma membrane per unit volume of structure, is more than 30 times higher in the neuropil than in the neuronal perikaryal fraction. The largest specific surface is found with (unmyelinated) axons and astroglial processes. The specific surface of the average astrocyte is about twice that of the average neuron. If the surface of the entire cell is considered in relation to the perikaryal volume only, this ratio is about seven times as large for glial cells as for neurons. It follows that an astrocyte perikaryon has to renew a several times larger plasma membrane than a neuron, which can account for the above differences in perikaryal synthesis rates of glycoconjugates.

Animals↗
PubMed1982

Nerve cells immunoreactive for vasoactive intestinal polypeptide in dissociation cultures of rat hypothalamus and midbrain.

Immunocytochemistry using the unlabeled antibody (PAP) technique reveals the presence of 0.01-0.3% neurons reacting with an antiserum against vasoactive intestinal polypeptide (VIP) in dissociation cultures of hypothalamus and midbrain. The cultures are obtained from 18-day-old rat fetuses and maintained for 22 and 29 days in vitro. Most of the neurons appear well differentiated giving off branched processes with pronounced varicosities. These can often be seen to contact perikarya as well as processes of unstained neurons.

Animals↗
PubMed1982

The significance of the subcompartments of the marginal zone for directing lymphocyte traffic within the splenic pulp of the rat.

These studies were designed to gain more detailed information on the sites of lymphocyte migration into the marginal zone, on lymphocyte segregation within this area and on subsequent migration of the cells in individual compartments of the rat spleen. A lymphocyte population enriched in T-lymphocytes was obtained from rat lymph nodes and was labeled with 5-(3H)uridine in vitro. Observations on localization of labeled lymphocytes at short time intervals following their intravenous transfusion into syngeneic recipients, indicate that the sites of emigration from the blood are the internal and external layers of the marginal zone. From here, the cells migrate towards the periarteriolar lymphoid sheath and the red pulp.

Animals↗
PubMed1982

Extraction of label during processing of brain tissue for electron microscopic autoradiographic investigation of glycoprotein metabolism.

Rats were injected intracerebrally with (3H) fucose and survived for 30 min and 24 h. Following perfusion fixation with aldehydes, Vibratome sections of the brains were processed for embedding in resin and the radioactivity in the various solutions measured by scintillation counting. The decline of radioactivity was monitored in up to 18 successive buffer washes. Whereas 85% of the initial radioactivity could be eluted after 30 min, only 7% were extractable after 24 h survival time. Addition of unlabelled L-fucose to the fixative and buffers caused a small insignificant increase of the total radioactivity extracted. Only small amounts of radioactivity could be removed by treatment with trichloroacetic acid after extensive rinsing in buffer. It is concluded that thorough rinsing in buffer (which is more important with short-time experiments) is effective in removing the acid-soluble radioactivity. An additional safe-guard lies in dehydration by ethanol. The ethanol series also removes acid-soluble radioactivity in addition to small amounts of what is probably higher molecular weight material.

Animals↗
PubMed1982

The development of immunoreactivity for neuron-specific enolase of preoptic and septal neurons in dissociated cultures.

The immunocytochemical visualization of neuron-specific enolase, which is a marker protein for differentiated neurons, was applied to follow the differentiation of preoptic and septal neurons in dissociated cultures. From 4 to 24 days in vitro, the relative numbers of stained neurons were counted and the staining intensity of individual neurons determined by absorbency measurements using a television-based densitometer. Whereas few stained cells could be observed at 4 DIV, 80% of the neurons were neuron-specific enolase-positive at 13 days in vitro. This value remained constant up to 24 days in vitro. The density of the immunoreaction product increased dramatically from 13 to 17 days in vitro and was still higher at 24 days in vitro. The glial and ependymal cells of the carpet, as well as neuroblasts, remained unstained. Comparison with morphological observations and immunocytochemical demonstration of neuronal peptides made earlier shows that expression of neuron-specific enolase closely parallels neuronal differentiation. These observations indicate that cultures derived from preoptic and septal neurons represent a viable model system for the study of neuronal maturation in vitro.

Animals↗
PubMed1981

Aspects of cellular proliferation during follicular atresia in the dog ovary.

Autoradiography after pulse labelling with [3H] thymidine was applied to investigate the proliferation processes in the granulosa and theca related to follicular atresia of the dog ovary during metestrus. The number of proliferating cells depends on the follicle type and its atretic stage. There is less proliferation in smaller secondary follicles than either in larger ones or tertiary follicles. While in early atresia tertiary follicles show the highest labelling indices, in advanced atresia the largest secondary follicles are those with the highest values. For each follicle type a decline in the labelling indices can be observed from early to terminal atresia. Tertiary follicles show a precipitous decrease in the labelling index between early and advanced atresia. There is a continuous gradient of proliferation from the center of the follicle over the peripheral granulosa to the theca. In tertiary follicles, an inverse correlation between labelling and necrosis of granulosa cells can be observed.

Animals↗
PubMed1981

The fine structure of the neural lobe of the mouse after transplantation under the kidney capsule.

The neurohypophysis of donor mice was implanted under the renal capsule of the recipients. The pituicytes survived while the neurosecretory axons disappeared. The ultrastructure of the glial cells was observed seven and nine weeks after transplantation. There were no signs of phagocytotic activity although remnants of axons were still present at seven weeks. The numerous processes of the pituicytes form a network with intercellular spaces wide in younger and narrower in older implants. The cells are connected by desmosomes and gap junctions. Pituicytes as well as blood vessels preserve their organotypic appearance. The transplant thus represents as experimental model for investigations on pituicytes in vivo in the absence of neurosecretory axons.

Animals↗