Fibrovascular Tissues Research Articles

Osteogenesis in extraskeletally implanted porous calcium phosphate ceramics: variability among different kinds of animals

Synthetic porous calcium phosphate ceramics (HA/TCP) were implanted intramuscularly and subcutaneously in dogs, pigs, goats, rabbits and rats, designed to make a comparative study of the host tissue responses to porous HA/TCP ceramics in different kinds of animals. Specimens were harvested at 15, 30, 45, 60, 90 and 120 days after implantation. Decalcified and undecalcified sections were made and examined by light microscopy. Obvious bone formation could be detected in some specimens harvested from dogs and pigs after 45 days intramuscular implantation or after 60 days subcutaneous implantation. At days 90 and 120, an extensive amount of bone formed in all specimens implanted in dogs and pigs. However, no histologically detectable bone formation was observed in any specimen implanted intramuscularly and subcutaneously in goats, rabbits and rats until 120 days. It is demonstrated from this finding that the synthetic porous calcium phosphate ceramics are capable of inducing osteogenesis when implanted in non-bony sites, but this ability varies between different kinds of animals. Earlier periods of observation in specimens harvested from dogs showed that bone differentiation in the pore regions of the ceramics follows a complex process involving invasion of the fibrovascular connective tissues at day 15, appearance of polymorphic mesenchymal cells near the invading vasculature and at the interface with the ceramics at day 30, differentiation of osteoblasts and formation of bone matrix in direct contact with the surface of the ceramics at day 45, and finally remodelling of the fibrous connective tissue into an extensive amount of bone at days 60, 90 and 120.

Fibrovascular Tissue in Bilateral Juxtafoveal Telangiectasis

To study the natural history and retinal findings associated with the intraretinal and subretinal fibrovascular tissues that develop in the late phases of bilateral juxtafoveal telangiectasis. The records of 10 patients (11 eyes) with bilateral juxtafoveal telangiectasis who developed these fibrovascular tissues were examined. Throughout the follow-up period (average 44 months), only 2 eyes (18%) lost 2 or more lines of vision; the final visual acuities were similar for the eyes both with and without fibrovascular tissues. Sixty-four percent of fibrovascular tissues showed little to no growth. Eyes with fibrovascular tissue commonly had retinal pigment epithelial hyperplasia (72%), draining retinal venules (82%), and retinal vascular distortion (64%). Fibrovascular tissues of bilateral juxtafoveal telangiectasis have little proliferative potential and minimal effects on visual acuity. Nevertheless, these fibrovascular tissues do remodel over time, leading to retinal vascular distortion. Given these benign findings, the role of laser photocoagulation treatment of these tissues is questionable.

Histologic study of living response to artificially synthesized hydroxyapatite implant: 1-year follow-up.

We implanted artificially synthesized hydroxyapatite spheres into the orbits of 13 rabbits after enucleation. The spheres were removed 1, 2, 3, 6, and 12 months after implantation and examined by light and scanning electron microscopy. Tissue breakdown and exposure of the artificially synthesized hydroxyapatite implants were not observed. Month after month, fibrovascular tissues gradually invaded the pores of the artificially synthesized hydroxyapatite spheres deeper and deeper. Although the hydroxyapatite we used was completely artificially synthesized, we observed a mild foreign-body reaction around the artificially synthesized hydroxyapatite spheres. After 12 months, however, relief of the foreign-body reaction had occurred. Hydroxyapatite spheres for orbital implants after enucleation without scleral enveloping are appropriate.

Granular Cell Basal Cell Tumor of the Eyelid in an F344 Rat

Granular Cell Basal Cell Tumor of the Eyelid in an F344 Rat

Refinements in Microinstrumentation for Vitreous Surgery

We developed a series of 25-gauge (0.5 mm) microinstruments for vitreous surgery, including a 25-gauge vitreous cutter, 25-gauge microscissors for limited reuse, and a vitreous membrane dissector. Clinical experience with these instruments in more than 20 cases of advanced proliferative vitreoretinopathy, retinopathy of prematurity, and diabetic retinopathy indicates that these instruments facilitate delicate vitreoretinal dissections, particularly in the vitreous base and when fibrovascular tissues are closely adherent to the retina. Because of their smaller size, the microinstruments are more precise in their cutting capabilities than other instruments.

Pathologic changes secondary to radiation.

AbstractIn order to be effective in the treatment of disease, especially neoplastic disease, radiation necessarily needs to be given in large doses. When treating tumors with high radiosensitivity in tissue of relatively low radiosensitivity, few complications of therapy occur. Frequently, however, the differential of sensitivity to radiation between the neoplasm and normal tissues exposed is small and the incidence of radiation injury to normal tissues becomes significant. Nowhere is this more apparent than in treatment of neoplasms during which the alimentary canal is heavily radiated. The following discussion will describe the pathologic changes that occur in the various units of the exposed alimentary tract and in various components of those units during and especially months or years after radiation therapy. The usual rapid and effective regeneration of the rapid‐renewal cell system after injury will be noted. The serious delayed manifestations of injury to the fibrovascular tissues with resulting delayed complications of ulcerations, stenoses, fistula formation, and obstructing adhesions will be emphasized. Brief discussions of several other organ systems injured by radiation will be presented.The development of second neoplasms as a result of radiation will be briefly mentioned and discussed from three standpoints: very low levels, low levels, and high levels of radiation.

Oviposition and Early Developmental Stages of Lestes eurinus (Odonata: Lestidae)

Selection of oviposition sites, oviposition, hatching, and the early larval stages of Lestes eurinus were studied in 1966. L. eurinus individuals oviposited in tandem above the water level in the fibrovascular tissues of Sparganium americanum. The female generally chose a section of the S. americanum leaf that was about halfway between the water level and leaf tip. Incisions were also more frequent in portions of the leaf nearest the midrib. As the reproductive period progressed oviposition occurred throughout most of the length and width of the leaf. The females, however, avoided the leaf tip and edges, which were unsuitable as oviposition sites. The egg stage exhibited no diapause, but developed directly and uniformly. In nature, egg development was calculated to last about six weeks. The eggs hatched inside the leaf and the animals emerged from the leaves in the prolarval stage, which lasted only a few minutes. It then molted into the second instar, the first stage in which the typical form and shape of the damselfly larva appeared. The egg stage of Lestes eurinus is relatively short and the winter is passed in several larval stages. Other published reports for representatives of this family have shown that most species have diapausing, overwintering, egg stages lasting abo-ut 30 weeks followed by rapid larval development.

Studies in Biology for New Zealand Students

THIS is a detailed study of the coarse and minute anatomy of a very familiar and widely-diffused weed. A native originally of the palæarctic region, it has now found its way to all temperate climates. It has certainly received at Prof. Hutton's hands, in the Antipodes, a more systematic investigation than ever fell to its lot in Europe. The treatment is much the same as that given to the bean (Faba vulgaris) in Huxley and Martin's “Elementary Biology,” though with a more botanical bias. The weakest part is the treatment of the root, where nothing is said about the mode of origin of branches. An earlier stage should have been taken, showing the arrangement of the fibro-vascular tissues before they had coalesced into a central cylinder. This however is simply by way of criticism. The method of treatment is excellent, and the Canterbury students are fortunate in being in the hands of a teacher who has such a thorough appreciation of the biological method as applied to botany.