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Biomedical subjects

M G Welsh

Publications and source records attributed to M G Welsh.

17 recordsLinked to original sources
PubMed1992

Third ventricular pineal gland grafts in the gerbil: an electron microscopical and immunohistochemical investigation.

The superficial pineal gland was grafted into the third ventricle of adult Mongolian gerbils. Donor pineal glands from both neonatal and 3-4 week old gerbils were able to survive for at least 6 months. The pinealocytes of the grafted superficial pineal glands maintained the morphology and the S-antigen immunoreactivity of the in situ pineal complex. Synaptic ribbons and spherules were present but rare. Unlike the in situ pinealocytes, glycogen accumulations were common in the graft pinealocytes. Site specific modulation of structure was indicated as the ventricular surface of the grafts became covered with cerebrospinal fluid (CSF)-contacting pinealocytes typical of those seen in the deep pineal. The CSF-contacting pinealocytes of the graft had numerous processes that extended along the ventricular surface of the graft. The blood vessels of the grafts had non-fenestrated endothelium and wide perivascular areas typical of those seen in the in situ pineal complex. Tyrosine hydroxylase-immunopositive nerve fibers were present in the grafted tissue indicating reinnervation of the graft. The source of the fibers was not determined. The nerve fibers were present both within the perivascular area and within the parenchyma where they were associated with pinealocytes. The results demonstrate that the cerebral ventricles are an ideal location for the survival of superficial pineal gland grafts. It is suggested that pineal grafts may be a means to further study pineal development and innervation.

Animals↗
PubMed1991

S-antigen and glial fibrillary acidic protein immunoreactivity in the in situ pineal gland of hamster and gerbil and in pineal grafts: developmental expression of pinealocyte and glial markers.

Postnatal development of S-Ag and GFAP immunoreactivity in the in situ pineal glands of golden hamsters and gerbils was examined using the avidin-biotin-peroxidase immunohistochemical technique. S-Ag was present in the gerbil pineal gland on the first postnatal day (P1), whereas it did not appear in the hamster pineal until P6. GFAP-immunoreactive astrocytes were first observed in the hamster pineal gland on P7 and in the gerbil pineal gland on P10. The number of S-Ag-immunoreactive pinealocytes and GFAP-immunoreactive astrocytes in the pineal glands of hamsters and gerbils increased with increasing age from P7 to 3 weeks. By 4 weeks, strong S-Ag and GFAP immunoreactivity was observed in both hamster and gerbil pineal glands. GFAP-immunoreactive stellate astrocytes were distributed evenly throughout the gerbil superficial pineal gland, but they were more often located in the peripheral region of the hamster superficial pineal. For the pineal grafts, pineal glands from neonatal (3-5 day old) hamsters were transplanted into the third cerebral ventricle (infundibular recess or posterior third ventricle) or beneath the renal capsule of adult male hamsters. S-Ag immunoreactivity appeared in the pineal grafts within 1 week following transplantation. By 4 weeks the pineal grafts showed strong S-Ag immunoreactivity which was maintained until at least 12 weeks after transplantation. The time course of glial cell maturation in the cerebroventricular pineal grafts is generally parallel to the hamster pineal gland in situ before 4 weeks. By 12 weeks, however, more astrocytes differentiated and developed GFAP-immunoreactivity in the pineal grafts than in the in situ pineals. These studies have described the postnatal development of S-Ag and GFAP immunoreactivity in in situ pineal glands and in neonatal pineal grafts.

Animals↗
PubMed1991

Application of confocal laser scanning microscopy to the deep pineal gland and other neural tissues.

The study of the deep pineal gland of the Mongolian gerbil and other neuronal tissue from the rat by means of confocal laser scanning microscopy (CLSM) is described. Opical serial sectioning was performed on thick (100-200 microns) sections of the deep pineal gland of the Mongolian gerbil stained immunohistochemically using antisera to S-antigen and tyrosine hydroxylase (TH). Both dual-stained and single-stained material was examined using the fluorochromes fluorescein isothiocyanate (FITC) and Texas Red. High resolution images were obtained showing that pinealocytes have 1-3 processes that extend primarily to other pinealocytes or presumptive pinealocytes. Pinealocytes are located within the deep pineal gland as well as adjacent to the posterior aspect of the medial habenular nuclei. Pinealocyte processes were not seen extending into the habenular nuclei, but rather ended within the deep pineal gland a significant distance from their perikarya. The TH-immunopositive fibers were distributed throughout the deep pineal gland, often forming "baskets" of fibers around pinealocytes rather than being associated primarily with blood vessels. Other uses of the confocal microscope are demonstrated on rat neural tissue reacted with peroxidase/diaminobenzidine (DAB) immunohistochemistry and FITC fluorescence immunohistochemistry (paraventricular nucleus) as well as Golgi-stained neuronal tissue (cerebral cortex). The HRP/DAB and Golgi-stained images were visualized using the reflected image mode of the confocal system.(ABSTRACT TRUNCATED AT 250 WORDS)

3,3'-Diaminobenzidine↗
PubMed1991

Tyrosine hydroxylase and neuropeptide-Y immunoreactivity in pineal glands developing in situ and in pineal grafts.

Postnatal development of the innervation of the pineal gland in situ as well as the reinnervation of pineal grafts by tyrosine hydroxylase (TH)- and neuropeptide Y (NPY)-immunoreactive nerve fibers were examined using the avidin-biotin-peroxidase immunohistochemical technique. TH-immunoreactive nerve fibers appeared in the pineal gland on the second postnatal day (P2) in both hamsters and gerbils. NPY-immunoreactive nerve fibers first appeared in the pineal gland of gerbils on P2 and in the hamsters on P3. By the seventh postnatal day (P7), the pineal glands of both hamsters and gerbils were richly innervated by TH- and NPY-fibers that appeared as smooth fibers or fibers with sporadic varicosities. By the age of 4 weeks, the innervation of the pineal glands of hamsters and gerbils by TH- and NPY-fibers was fully developed. Abundant TH- and NPY-fibers formed a dense meshwork in the parenchyma of the superficial and deep pineals. The great majority of the fibers bore a large number of varicosities. More NPY-fibers were found in the pineal glands of gerbils than hamsters. NPY fibers were distributed evenly throughout the pineal glands of the gerbil, but they were more often located in the central region of the superficial pineal of the hamster. For the pineal grafts, superficial pineals from neonatal and 4-week-old hamsters were transplanted to different sites in the third cerebral ventricle (infundibular recess, posterior third ventricle) or beneath the renal capsule. The pineal grafts from 4-week-old donors appeared to undergo severe degeneration and eventually disappeared. The pineal grafts from neonatal hamsters, however, successfully survived and became well integrated into their new locations. Abundant TH- and NPY-fibers in the host brain were found surrounding the pineal grafts placed in the third cerebral ventricle, but were only rarely seen entering the parenchyma of the grafts. A few TH-fibers were demonstrated in the renal grafts 4 weeks after transplantation. These studies describe the postnatal development of the innervation of the pineal glands in situ by TH- and NPY-nerve fibers, and demonstrate a lack of reinnervation of cerebroventricular pineal grafts by TH and NPY fibers from adjacent host brain.

Animals↗
PubMed1989

Timing of Silastic tubing removal after intubation for congenital nasolacrimal duct obstruction.

One thousand five hundred twenty-one patients (2,038 eyes) with congenital nasolacrimal duct obstruction were reviewed at The Children's Hospital of Philadelphia. Of these, 174 patients with congenital dacryostenosis involving 192 eyes underwent polymeric silicone (Silastic) intubation to treat the dacryostenosis. All patients had undergone at least several months of conservative management consisting of topical antibiotics and massage. All had undergone at least one probing and irrigation. Congenital dacryostenosis as well as resolution of symptoms were confirmed by clinical examination and use of a modified dye disappearance test. In 192 eyes the overall success rate was 83.33%. When broken down into age group, progression of success rates were from 100% in the 6-13 month age group to 79.6% in the over 24-month age group. Success rates differed significantly according to how long the Silastic tubing remained in position, especially in older age groups. The data suggest that Silastic intubation is a successful means of treating congenital dacryostenosis and that one should consider leaving the silastic in place for 6 months when possible.

Age Factors↗
PubMed1989

Cerebrospinal fluid-contacting area of the deep pineal: effects of photoperiod.

The surface of the pineal recess of the Syrian hamster demonstrates three morphologically distinct zones that are classified as the peripheral, transitional, and central zones. The central zone is the most remarkable because of the number of distinguishable morphological specializations in this region that appear to indicate interaction between the cerebrospinal fluid (CSF) and associated ventricular structures and the deep pineal gland. CSF-contacting pinealocytes are present in the central zone and have a relatively indistinct ventricular surface except for the presence of surface blebs and pinealocyte processes that course on the surface of the deep pineal. Supraependymal neurons and neuronal processes appear to converge on the central zone, occasionally having presumptive terminals that are associated with the cells of the central zone. When the hamsters were maintained in a short photoperiod (LD 8:16), the CSF-contacting area of the pineal recess was significantly larger in those hamsters killed 2 hours before lights off compared to those killed 2 hours before lights on (P less than 0.01). There were no significant differences in the CSF-contacting area when comparing two groups of hamsters maintained in a long photoperiod (LD 14:10, killed 2 hours before lights on and lights off, respectively). There was statistically significant interaction (P less than 0.05) between the lighting cycle and the time of day of death on the appearance of CSF-contacting pinealocytes. The hamsters maintained in LD 8:16 had significantly reduced testicular weights when compared to those maintained in LD 14:10. The plasticity of the central zone and the associated CSF-contacting pinealocytes of the pineal recess of the hamster are evidence that this region demonstrates morphological changes that are dependent upon the physiological state of the animal.

Animals↗
PubMed1987

Ocular and adnexal complications of unilateral orbital advancement for plagiocephaly.

Strabismus, ptosis, lateral canthal dystopia, nasolacrimal obstruction, and cranial nerve palsy were noted preoperatively in 32%, 21%, 14%, 12%, and 9% of 34 patients, respectively, undergoing ophthalmologic evaluation prior to unilateral orbital advancement for plagiocephaly. Thirty-two percent of the patients had normal preoperative ocular and adnexal examination results. Ptosis, strabismus, and amblyopia were frequently acquired postoperative abnormalities in 29%, 18%, and 18% of the patients, respectively. Forty-four percent of the patients had no new abnormalities following craniofacial surgery.

Child↗
PubMed1987

Intraventricular blood vessels associated with the deep pineal gland of the Mongolian gerbil, Meriones unguiculatus.

Intraventricular blood vessels and choroidal-like cells were studied using scanning electron microscopy and correlative light microscopy. The intraventricular blood vessels were covered on their ependymal surface with a layer of cells essentially identical to the ependyma of the choroid plexus in the gerbil. Similar choroidal-like cells were seen either singly or in clusters associated with the cerebrospinal fluid-contacting pinealocytes of the suprapineal recess. Processes of the cerebrospinal fluid-contacting pinealocytes were seen extending to and making contact with the choroidal-like cells. The intraventricular blood vessels appeared to be derived from the choroid plexus, and typically took one of three courses in and around the surface of the deep pineal: (1) the vessels or their equivalent were located in the suprapineal recess with no indication of penetration into the substance of the deep pineal; (2) the vessels coursed from the suprapineal recess around the anterior surface of the habenular commissure to enter the ventral surface of the deep pineal; or (3) the vessels entered the parenchyma of the deep pineal from its dorsal surface and could be seen coursing through the substance of the gland. The close association between the choroidal-like cells and the intraventricular blood vessels with the deep pineal gland add morphological support for the possibility of interaction between the cerebrospinal fluid, or perhaps the choroid plexus, and the deep pineal gland.

Animals↗
PubMed1987

Timing of initial probing and irrigation in congenital nasolacrimal duct obstruction.

A series of 427 patients with congenital dacryostenosis involving 572 eyes was seen at the Children's Hospital of Philadelphia. All patients were treated conservatively with antibiotics and massage prior to decision by the parents to request probing. Congenital dacryostenosis, as well as resolution of symptoms, were confirmed by clinical examination and use of a modified dye disappearance test. In 572 eyes, the success rate of initial probing was found to be 97% under 13 months of age. Over 13 months, however, the mean success rate was found to be 54.7%. When broken down into smaller age categories, a stepwise progression was observed from 76.4% between 13 and 18 months to 33.3% for patients probed after 24 months. In addition, the number and complexity of subsequent procedures appeared to increase along with the age at which the initial probing was performed. These data suggest that initial probing should be done prior to 13 months of age depending on the severity of symptoms and parent compliance with medical management.

Child, Preschool↗
PubMed1987

Three-dimensional computed tomographic imaging.

Recent developments in imaging techniques now allow reconstruction of actual three-dimensional images from computed tomographic data. This article discusses the basic concepts involved in three-dimensional imaging and reviews its potential as a diagnostic and management tool for the clinical ophthalmologist. New computer techniques allow review of actual three-dimensional images in both static and dynamic formats. This can allow the clinician to define more accurately a normal and pathologic anatomy involving skeletal structures in particular.

Eye Diseases↗
PubMed1987

An ultrastructural examination of murine alveolar macrophages following intranasal administration of propionibacterium acnes.

Light and electron microscopic analysis of murine lungs or isolated pulmonary cells was performed three days after intranasal administration of the bacterial immunostimulant, Propionibacterium acnes (P. acnes). Our observations indicated that pulmonary alveolar and airway macrophages (PAMs) were the only cells with P. acnes bacilli in their cytoplasm. Bacilli were not observed in pulmonary interstitial macrophages, granulocytes, lymphocytes or pulmonary parenchymal cells such as type I and type II pneumocytes. Because of the morphological heterogeneity of PAMs observed in control and experimental animals, it was not possible from these studies to be certain about the relative abundance or complexity of lysosomes, endoplasmic reticulum, Golgi and other organelles in the two groups. However, we noted that it was not uncommon to observe in the same PAM, profiles of P. acnes and a well developed Golgi complex and endoplasmic reticulum. These P. acnes--associated morphological alterations occurred at a time when functional activities (e.g., phagocytosis, cytostasis) of PAMs were enhanced.

Animals↗
PubMed1985

Pseudallescheria boydii (Petriellidium boydii) infection of the orbit.

A 10-year-old male developed a chronic orbital infection following penetrating trauma and retention of an orbital foreign body. Diagnosis of infection with Pseudallescheria boydii (Petriellidium boydii) was made by fungal smear and culture. Sensitivity tests indicated the organism was resistant to amphotericin B. Surgical debridement of the inferior orbit and removal of the foreign body was followed by a six-week course of intravenous miconazole. The patient has shown no signs of recurrence in a two-year follow-up period. To our knowledge, this is the first reported case of orbital infection with Pseudallescheria boydii, although the organism has been reported in cornea, ocular, and peri-orbital sinus infections.

Ascomycota↗
PubMed1979

The pineal gland of the gerbil, Meriones unguiculatus. II. Morphometric analysis over a 24-hour period.

By means of morphometric analytical procedures, a diurnal rhythm in the cellular volume of gerbil pinealocytes was determined. This rhythm has been attributed primarily to a change in the cytoplasmic volume of the pinealocytes which is low during the daylight hours and increases to reach a peak during the middle of the dark period. At the ultrastructural level, six cytoplasmic components of the pinealocytes were found to exhibit a rhythm: free cytoplasm, smooth endoplasmic reticulum (SER), rough endoplasmic reticulum (RER) and ribosomes, secretory vesicles, microtubules, and mitochondria. The presumptive secretory vesicles and the microtubules reached a peak in volume one hour before lights-off. It is suggested that lights-on and lights-off both signal a decrease in size and/or number of the secretory vesicles. The SER and RER/ribosomes reached their peak volume one hour after lights-off which is interpreted as indicating a peak in indoleamine synthesis and protein synthesis, respectively. The volume of free cytoplasm exhibits two peaks; one occurs one hour before lights-off while the second peak occurs in the middle of the dark phase. It is suggested that, although part of the secretory product of the pinealocyte may be present in dense-cored vesicles, other locations could include the free cytoplasm and clear secretory vesicles.

Animals↗
PubMed1979

The pineal gland of the gerbil, Meriones unguiculatus. III. Morphometric analysis and fluorescence histochemistry in the intact and sympathetically denervated pineal gland.

Morphometric analytical procedures were employed to study the pineal gland of the Mongolian gerbil following superior cervical ganglionectomy (SCGX). The purpose of this study was to define the effects of sympathetic denervation on the morphology of the gland at two time periods, 0500 and 1900 h (one hour before lights-on and lights-off, respectively). Fluorescence histochemistry was employed to determine catecholamine and indoleamine content in intact and denervated pineal glands. After SCGX, the pinealocytes decrease in size, concretions are prevented from forming, and the yellow fluorescence in the gland is lost. Following denervation a depression in the volume of most of the pinealocyte organelles, i.e., SER, RER/ribosomes, free cytoplasm, mitochondria and presumptive secretory vesicles, was also observed. However, synaptic ribbons increased in volume in the gerbils that had been killed at 1900 h. It appears that the sympathetic innervation to the pineal gland is a requirement for the presumptive secretory activity of the pinealocytes.

Animals↗
PubMed1978

The pineal gland of the gerbil, Meriones unguiculatus. I. An ultrastructural study.

Electron microscopy was employed in a study of the pineal gland of the Mongolian gerbil (Meiones unguiculatus). It was determined that the gerbil pineal gland contains pinealocytes and glial cells with the pinealocytes being the predominant cell type. The pinealocytes contain numerous organelles traditionally considered as being either synthetic or secretory in function such as an extensive Golgi region, smooth (SER) and rough (RER) endoplasmic reticulum, secretory vesicles and microtubules. Other cytoplasmic components are also present in the pinealocytes (synaptic ribbons, subsurface cisternae) for which no function has been assigned. Dense-cored vesicles are rare. Vacuolated pinealocytes are present and appear to be intimately associated with the formation of the pineal concertions. Evidence presented supports the proposal that the concretions form within the vacuoles. Once the concretions reach an enlarged state, the vacuolated pinealocytes break down and the concretions are thus extruded into the extracellular space where they apparently continue to increase in size. The morphology of the glial cells was interpreted as indicative of a high synthetic activity. The glial cells contain predominantly the rough variety of endoplasmic reticulum and form an expansion around the wide perivascular area.

Animals↗
PubMed1976

Age-related changes in the intact and sympathetically denervated gerbil pineal gland.

The pineal gland of four-month-old gerbils contains numerous calcareous deposits (corpora arenacea or concretions). Also, the tissue appears vacuolated due to the presence of a number of large rounded spaces. The deposits are usually associated with or lying within these "vacuoles". By eight months of age, the number of both the corpora arenacea and the "vacuoles" are increased over those present in the pineals of four-month-old gerbils. Bilateral superior cervical ganglionectomy at one month of age prevents the formation of both the concretions and "vacuoles". The cells in the sympathetically denervated pineal glands are smaller than those in pineal glands of animals that possess intact superior cervical ganglia.

Aging↗