Biomedical subjects

D Tolivia

Publications and source records attributed to D Tolivia.

At least 19 recordsLinked to original sources

PubMed1992

Female Syrian hamster Harderian gland: development and effects of high environmental temperature and melatonin injections on histology and porphyrin deposits.

We have investigated the development of the Harderian glands of female Syrian hamsters from birth to 8 months of age. The effects of melatonin injections on Harderian gland histology and porphyrin deposits of female hamsters exposed to two different temperatures were also studied. The morphology of the Harderian glands from 30-day-old female hamsters resembled those of sexually mature adult animals. The intraluminal area occupied by porphyrins increased significantly between 20 to 30 days of age. However, the relative number of mast cells per mm2 rose between 30 to 90 days. Both porphyrins and mast cell numbers appeared clearly reduced in the 8-month-old group. Secretory cells characterized by large lipid droplets (type II cells) were not observed. Daily afternoon injections of 25 micrograms of melatonin to female hamsters exposed to 22 degrees C for 14 weeks resulted in the discontinuity of estrous cyclicity, a marked decrease in the intraluminal area occupied by porphyrins, a reduction of the number of mast cells per mm2, and in a marked augmentation of the number of type II cells per mm2. Although the administration of similar dosages of melatonin to hamsters exposed to an environmental temperature of 32 degrees C did not interrupt estrous cycles, a clear reduction of the area occupied by porphyrins was observed. However, the number of mast cells and type II cells per mm2 was unaffected in these animals. Our results suggest that hormones other than ovarian steroids are involved in the regulation of the female hamster Harderian glands. The possible role of melatonin on Harderian gland metabolism is discussed.

Animals↗

PubMed1992

Lymphoid cells in the harderian gland of the rodent Octodon degus.

The Harderian gland of the degu (Octodon degus) is composed of tubulo-alveolar secretory units that share most of morphological features found in the Harderian glands of other rodents. However, a peculiar characteristic observed in the glands of female degus is the existence of lymphoid cell clusters within the connective tissue surrounding the secretory adenomeres. Lymphocytes and lymphoblasts are found associated with blood vessels and especially with nerve bundles in the medullary region of the gland. Occasionally, macrophages and plasma cells are also observed. Although the Golgi apparatus appears well developed, the ultrastructural characteristics of most of these lymphoid elements correspond to those of inactive lymphocytes. Unmyelinated fibers containing clear and dense-core vesicles are found closely related to lymphocytes. On some occasions, lymphocytes present extensive areas of apposition with structures resembling intercellular junctions. The analogy of the lymphoid clusters reported in this study with those described in the avian Harderian gland is discussed.

Animals↗

PubMed1992

Development and hormonal regulation of mast cells in the Harderian gland of Syrian hamsters.

The morphological features and relative number of mast cells per mm2 were studied in the Harderian glands of male and female Syrian hamsters (Mesocricetus auratus) under different experimental conditions. The structural and ultrastructural characteristics of Harderian mast cells corresponded to those of connective tissue mast cells. The Harderian glands from female hamsters contained more mast cells than those of male hamsters. A subcutaneous implant of testosterone (2 mg/24 mg beeswax) resulted in a rapid decrease in the number of recognizable mast cells 6 h after the implantation. Neither orchidectomy nor ovariectomy significantly altered the relative number of mast cells. However, the daily subcutaneous injection of 20 IU of human chorionic gonadotropin during 20 days resulted in a significant decrease of identifiable mast cells. The administration of another steroid such as progesterone or the induction of states of hypo- and hyperthyroidism did not alter the distribution of mast cells in the Harderian glands of female Syrian hamsters.

Age Factors↗

PubMed1992

Effects of human chorionic gonadotropin and progesterone administration on porphyrin biosynthesis and histology of the Harderian glands in male and female Syrian hamsters.

We investigated the influence of hCG and progesterone on the control of porphyrin biosynthesis and histology in the Syrian hamster Harderian glands. Castration of male hamsters caused a marked elevation in porphyrin biosynthesis as revealed by the concentrations of porphyrins and the mRNA levels of the porphyrin pathway rate-limiting enzyme, 5-aminolevulinate synthase (ALV-S). Injection of hCG into castrated male hamsters also resulted in a significant increase in both porphyrin concentrations and levels of ALV-S mRNA compared with those in saline-injected castrated hamsters. Type II cells, which are filled with large lipid vacuoles and are characteristic of male phenotype, disappeared after castration, but administration of hCG partially prevented this change. On the other hand, neither administration of hCG nor progesterone implants could increase the very high porphyrin concentrations and ALV-S mRNA levels characteristic of female Syrian hamsters. As in the case of castrated male hamsters, injections of 20 IU hCG to female Syrian hamsters increased the relative number of Type II cells per square millimeter, whereas progesterone administration did not modify the relative number of Type II cells. These results indicate that hCG can modify Harderian gland morphology in both male and female hamsters and can exert a positive control in the expression of ALV-S gene in castrated male hamsters.

5-Aminolevulinate Synthetase↗

PubMed1992

The pineal gland of the trumpet-tailed rat (Octodon degus).

The structure and ultrastructure of the pineal gland of the degu or trumpet-tailed rat (Octodon degus), a rodent inhabiting tropical-equatorial areas, was examined under light and electron microscopy. On the basis of its form, size, and location, the pineal gland of the degu is classified as a proximal or "A" type. The connective tissue appeared poorly developed and the gland contained non-fenestrated capillaries. A single population of typical pinealocytes was found. In addition, a small number of glial cells and cells with electron dense bodies appeared scattered throughout the gland. Cells with dense granules were found isolated or forming small groups always in close proximity to blood vessels. Numerous sympathetic nerve fibers with small dense-core vesicles were found. Also, some myelinated nerve fibers were observed. The physiological significance of the presence of large electron-dense granules in some pineal cells and their particular location around the blood vessels in discussed.

Animals↗

PubMed1991

A new rapid silver impregnation for neuronal bodies on methacrylate sections.

A simple and rapid method for the impregnation of neuronal bodies applicable to methacrylate embedded sections is described in the present paper. Sections of 10-12 microns in thickness were attached to slides, placed in mordant for 1 min, rinsed in distilled water and impregnated in ammoniacal silver solution for 1 min. They were then rinsed in absolute ethanol for 30 s and developed in 50% formalin. Sections were toned in 0.25% gold chloride, reduced in 10% oxalic acid and fixed in 5% sodium thiosulfate. After washing, the sections were dehydrated through 90% and absolute ethanol, cleared in eucalyptol, and mounted in the usual way. When this method is used most of the neuronal somata and proximal dendritic trees are impregnated. Frequently some glial cell are also weakly impregnated but their density does not obscure the neurons.

Animals↗

PubMed1991

Chronic administration of melatonin induces changes in porphyrins and in the histology of male and female hamster harderian gland: interrelation with the gonadal status.

In this paper, we have investigated the influence of melatonin on the histology and porphyrin content of the Syrian hamster Harderian glands. Daily afternoon injections of 25 micrograms of melatonin to female hamsters for 12 weeks resulted in the discontinuity of estrous cyclicity, a marked decrease in the Harderian gland intraluminal area occupied by porphyrins, and in a significant rise in the number of Type II cells. A similar decrease in porphyrins was observed after 8 weeks of ovariectomy. However, if the melatonin injections were given for only 8 weeks (without inducing gonadal atrophy), no changes were observed in the area occupied by intraluminal porphyrins, suggesting that the effects of melatonin in female Syrian hamsters might be associated with the subsequent gonadal atrophy. Castration of male hamsters induced a significant increase in porphyrins and a clear drop in the number of Type II cells. These changes were totally prevented when melatonin was administered daily from the day of castration. Our results suggest that melatonin, at least in male Syrian hamsters, plays a role in Harderian metabolism, acting directly on the Harderian secretory cells or indirectly through pituitary hormones.

Animals↗

PubMed1990

Ultrastructural study of the cellular types in the pineal organ of Gambusia affinis (teleost).

The pineal organ of Gambusia affinis was studied via light and electron microscopy. The cell types studied included photoreceptor cells, supporting cells, and a third cell type. The photoreceptor cells, which appear to form clusters, are divided into four regions: outer segment, inner segment, cell soma, and synaptic pedicle. Synaptic ribbons are commonly observed in the synaptic pedicle. The supporting cells separate the photoreceptor cells from the thick basal lamina that surrounds the entire pineal organ. The supporting cells show highly organized membrane formations, some lipid-like inclusions, and a diplosome. One of the centrioles gives rise to an invaginated cilium. The third cell type is observed infrequently and appears to be located mainly in the vicinity of the outer segments. The morphological characteristics of this cell type are similar to those of phagocytic cells. The ultrastructural features of the pineal organ of G. affinis are compared with those of other teleosts.

Animals↗

PubMed1990

Ultrastructure of the blood vessels in the Harderian gland of the hamster (Mesocricetus auratus): existence of sinusoids.

The Harderian gland blood supply of female and male hamsters was studied using light and electron microscopy. A profuse vascularization surrounding secretory acini was observed. Among the blood vessels, the existence of large and irregular sinusoidal capillaries was apparent. These sinusoids appeared in close association to the basal aspect of the secretory cells. Typical, small, fenestrated capillaries were also observed within the connective tissue. The existence of this particular vascularization together with other morphological features of the secretory cell basal pole suggest a possible endocrine function of these orbital glands.

Animals↗

PubMed1989

Differential thionin block staining of nerve cells and fibers for paraffin-embedded material in mammalian central nervous system.

A differential staining method of myelinated fibers and nerve cell bodies applicable to whole blocks of mammalian central nervous tissue is described. Experimental material fixed by perfusion or necropsy material fixed in block can be used. Blocks of 2 mm in thickness were obtained with a vibratome, immersed in 50% ethanol for 7 h and stained for 1 week in the following solution: 0.3% thionine, 5% formaldehyde and 5% acetic acid. After the staining period the blocks were washed in distilled water, dehydrated through graded alcohols, cleared in butyl acetate and infiltrated in paraffin. Sections of 10 microns in thickness were obtained, attached to slides, dewaxed in xylene and coverslipped with mounting media in the usual manner.

Animals↗

PubMed1989

Membrane formations in the pineal cells of the teleost Gambusia affinis.

Highly organized membrane formations in the cytoplasm of photoreceptor and supporting cells of the pineal organ of Gambusia affinis are described. These membranous structures show different characteristics depending on the cell type where they are located. Some of the morphological characteristics of these membranous formations are similar to those of myeloid bodies, but their presence in the photoreceptor cells raises some doubt about their being myeloid bodies. The three-dimensional interpretation of these structures is discussed.

Animals↗

PubMed1988

New technique for differential staining of myelinated fibers and nerve cells on paraffin sections.

A simple, rapid method for the differential staining of myelinated nerve fibers and nerve cell bodies, applicable to sections of central nervous system pieces embedded in paraffin, is described. Experimental material fixed by perfusion with mixed aldehydes or necropsy material fixed in formaldehyde can be used. Constant and homogeneous results are obtained with this technique, and the most important characteristic is the absence of differentiation in either of the steps: staining of myelinated fibers and staining of nerve cell bodies. Sections 15 microns thick were attached to slides, dewaxed, and hydrated. After hydration, sections are mordanted (30 min) in 2.5% iron alum (SO4)2FeNH4, and rinsed (1 min) in distilled water. Staining is for 180 min in the following solution: 5 ml freshly made 20% alcoholic hematoxylin diluted with 25 ml of distilled water and 25 ml of absolute ethanol to which 10 ml of 1% Li2CO3 is added. The sections are washed in distilled water (5 min) and stained during 5 min in the following solution: 0.2% pyronine, 20% formaldehyde in distilled water. The sections are dehydrated through 96% and absolute ethanol, cleared in eucalyptol, and mounted in Eukitt. Myelinated fibers appear dark blue, whereas nerve cell bodies are stained red and the cell nucleoli dark blue. This procedure provides an adequate contrast for observation and photography.

Animals↗

PubMed1987

Differential technique to stain nerve cells and fibers in methacrylate sections.

A simple method for the simultaneous staining of nerve cells and fibers, applicable to sections of pieces embedded in methacrylate, is described. Sections of 12 micron in thickness were attached to slides and stained for 10-18 hours in the following solution: 0.03% thionin, 0.5% formaldehyde, 0.5% acetic acid in distilled water. They were then rinsed in acetic water (0.5% acetic acid) for 30 seconds, washed in distilled water, dehydrated through 96% and absolute ethanol, cleared in eucalyptol, and mounted in Eukitt.

Animals↗

PubMed1987

A new rapid silver impregnation for neuronal bodies.

Frozen sections of avian and rat brains routinely fixed in 6% glutaraldehyde/2% paraformaldehyde and left in phosphate buffer for 1 month are cut at 15-20 microns and collected in distilled water. Sections are placed in ammoniacal silver solution for 30 s, rinsed in 100% acetone and developed in a reducing solution at 75 degrees C. Sections are toned in 1% gold chloride solution and fixed in 50% sodium thiosulfate. After washing, the sections are dehydrated, cleared and mounted in the usual way for light microscopy.

Animals↗

PubMed1987

The hypothalamic magnocellular system in the domestic fowl. Study on semithin sections.

Neuronal characteristics and location of the neurosecretory, magnocellular, fuchsin-paraldehyde-positive (FA+) system of the fowl are described at the light-microscopic level on serial semithin sections. Three nuclei make up this system, the nucleus supraopticus, n. magnocellularis interstitialis and n. paraventricularis. These nuclei display magnocellular neurons, not showing a parvocellular component. The neurons of the three nuclei showed a scattered pattern of distribution and a dense surrounding neuropil. Groups formed by magnocellular neurons were found in the three nuclei and groups formed by one magnocellular and a parvocellular neurons were only found in the n. magnocellularis interstitialis and in the n. paraventricularis. The presence of neurons in apposition to blood vessels was frequent in the magnocellular FA+ system of the domestic fowl.

Animals↗

PubMed1986

A threedimensional reconstruction program for personal computers.

A reconstruction program is described for personal computers, permitting threedimensional image reconstructions from serial sections. This program also makes it possible to calculate the volume of structures from their twodimensional images in histological sections. In this paper we show a program written in BASIC and debugged on a Sharp MZ-700 personal computer, equipped with the Sharp MZ-1P01 plotter. The program is explained in detail and is easily adapted to run on any personal computer.

Computers↗

PubMed1986

A new and permanent staining method for starch granules using fluorescence microscopy.

A fluorescence technique has been developed for observing starch granules in plant tissues. Sections are stained with a mixture of dyes which we have named F.A.S.G.A. from the initials of the Spanish names of its components (fucsina, alcian blue, safranina, glicerina, agua), and viewed by epifluorescence microscopy. The starch granules fluoresce greenish yellow, allowing the degradative state to be observed. Cell structures which do not fluoresce are also differentiated. The stain permits identification of other structures when examined by visible light microscopy and is relatively resistant to fading over time.

Fabaceae↗

PubMed1985

A new technique for differential and simultaneous staining of nerve cells and fibers.

A new and simple method for the simultaneous staining of nerve cells and fibers is described. The use of formol-thionin under controlled conditions of concentration and pH provides a highly reliable method for the staining of nerve cells in blue and fiber tracts in red, making any posterior differentiation redundant. This technique provides constant and reproducible results allowing simultaneous staining of many sections.

Animals↗