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Biomedical subjects

Y R Barishak

Publications and source records attributed to Y R Barishak.

18 recordsLinked to original sources
PubMed1992

Embryology of the eye and its adnexae.

The embryonal and fetal development of the human eye includes a series of sequential events starting with the fertilization of the ovum and culminating in the birth of a normal baby. Three main periods can be distinguished in the prenatal development of the eye. The first period called embryogenesis is characterized by the establishment of the primary organ rudiments and ends at the end of the 3rd week with the appearance of the optic sulci on both sides of the midline at the expanded cranial end of the still open neural folds. The second period called organogenesis includes the development of the primary organ rudiments and extends till the end of the 8th week. The third period involves the differentiation of each of the primitive organs into a fully or partially active organ and is called differentiation. The period of embryogenesis is characterized by the appearance and migration of the neural crest cells and by the formation of the primary brain vesicles. The period of organogenesis extends from the 4th week till the end of the 8th week. The 4th week shows the closure of the neural canal anteriorly with the subsequent evagination of its lateral wall into optic vesicles, the invagination of the lower nasal wall of the optic vesicle causing the formation of the optic cup, and the development of the lens plate, retinal disk and embryonic fissure. The embryonic fissure extends into the optic stalk which connects the cavity of the optic vesicle with the cavity of the neural canal; the hyaloid artery penetrates into the optic cup through the embryonic fissure. During the 5th week, the optic cup is concluded, and the cells of its external layer acquire pigmentation as a result of contact with developing capillaries in the periocular mesenchyme; these capillaries anastomose with each other and form anteriorly the annular vessel. The lens plate develops into a lens pit and later into a lens vesicle which separates soon thereafter from the surface ectoderm. Inside the optic cup, the hyaloid vessels form the capillaries of the posterior tunica vasculosa lentis and through the capillaries of the lateral tunica vasculosa lentis anastomose with the annular vessel. The primary vitreous forms and the surface ectoderm overlying the lens vesicle differentiates into a primitive corneal epithelium. The facial and orbital structures also develop at this stage. The 6th week shows the incipient differentiation of the inner layer of the optic cup into a sensory retina, the formation of the secondary vitreous, the transformation of the posterior cells of the lens vesicle into primary lens fibers, the development of the periocular vasculature and the appearance of the first eyelid folds and of the anlage of the nasolacrimal duct. However, the dominating factor is the closure of the embryonic fissure.(ABSTRACT TRUNCATED AT 400 WORDS)

Cell Differentiation↗
PubMed1989

Intraocular pressure in cats is lowered by drops of hornet venom.

1. Nine cats were given an intravenous injection of the Oriental hornet (Vespa orientalis, Vespinae; Hymenoptera) venom sac extract (VSE) and seven cats had the same VSE administered as eye drops. 2. When injected intravenously, the hornet VSE decreased the intraocular pressure in both eyes sharply during the first 20 min and with a slower rate later on until the end of the 3 hr experiment. The intraocular pressure dropped to zero in some cases. 3. VSE eye drops decreased the intraocular pressure only in the treated eye, while in the second eye (left as a control) the intraocular pressure remained the same throughout the experiment. 4. The decrease in the intraocular pressure was sharp during the first 20 min and slowed down afterwards until the end of the experiment. 5. The intraocular pressure did not reduce to zero. 6. This study shows that the active components of the hornet venom which caused a decrease in the intraocular pressure can cross the cornea and exert a hypotensive effect in the eye.

Animals↗
PubMed1986

Foreign-body giant cell reaction to liquid silicone.

Although intravitreal injections of liquid silicone have long been used in complicated retinal detachments and long-term complications such as keratopathy, glaucoma, and cataract are well-known, the effect of liquid silicone on the retina, iris, and angle structures is not as well defined. Histopathologic study of one human eye that was enucleated 20 months after liquid silicone injection showed an intraocular foreign-body giant cell reaction.

Adult↗
PubMed1985

Intraocular ossification.

Intraocular ossification was investigated in a series of 20 eyes. Only 12 eyes were phthisical. The etiological factors were trauma, inflammation, glaucoma and massive intraocular gliosis. Bone tissue was of the compact and spongy type. A correlation was found between the intraocular ossification and retinal detachment, intraocular hemorrhage, intraocular neovascularization and uveitis.

Adolescent↗
PubMed1979

The effect of chloroquine upon the developing lens.

Applied to the developing lens of the 14-day-old chick embryo, in organ culture conditions, chloroquine prevented the elongation of the primary lens fibres, destroyed the equatorial ones and provoked vacuolisation and/or destruction in the epithelial cells.

Animals↗
PubMed1978

The development of the angle of the anterior chamber in vertebrate eyes.

The development of the angle of the anterior chamber of the eye in chick embryos (avian eye), in new born rats (rodents), in calf fetuses (ungulates) and in humans (primates) has been studied. The main determinant in the configuration of the angle is the two-layered structure of the mesoderm of the ciliary body: the external muscular layer inserted into the spur and growing with same growth rate as that of the corneoscleral mesoderm and internal fibrovascular layer giving rise to the ciliary processes and growing with same growth rate as that of the neural ciliary and iris epithelium. First the neural epithelium grows faster than the corneoscleral mesoderm and the ciliary processes appear anteriorly positioned and later the corneoscleral mesoderm grows faster than the neuroepithelium and the ciliary processes appear posteriorly positioned. The eyes of premature and low birth weight babies present the different stages of normal embryological development of the angel. The angle in eyes of various embryopathies and developmental diseases presents aspects similar to those of the premature and low birth weight babies. The etiopathogenic mechanism in cause is the same in both groups: arrest of development. During the first post-natal years, the corneoscleral mesoderm grows at a greater rate than the inner neuro-epithelium and the region of the most active growth is located at the ora serrata. That is why, during this period, the ora serrata recedes, giving rise to the formation of retinal teeth, the angle despens and makes a recess and the Lange fold disappears.

Animals↗
PubMed1978

Histopatholocial changes in siderosis bulbi.

The histopathology of indirect siderosis bulbi induced by iron intraocular foreign bodies which penetrated into the posterior segment of the eye, is reported. Iron ions dispers into the vitreous first and in the aqueous humor later and then they enter into all the tissues which surround the vitreous and the aqueous. Iron ions penetrate also into the suprachoroidal space through the angle. The importance of this route of penetration upon the appearance of atypical ERG finding in siderosis bulbi is briefly mentioned.

Adult↗
PubMed1978

Controlled mechanized trepan.

A mechanized trepan is described whose cutting action is halted automatically when the trepan's cutting edge reaches the last 0.03 mm. tissue layer of the cornea. The automatic half of both the motor which advances the trepan as well as the second motor which rotates the trepan is triggered by the sudden change in electrical resistance between the trepan and the patient's internal body fluid, at the final stage of penetration. This automatic feature eliminates the danger of inadvertant damage to the inner structures of the eye.

Corneal Transplantation↗
PubMed1978

The effect of conservative treatment on the choroidal melanoma: histopathologic study.

Sixteen eyes harboring a choroidal or a ciliary body melanoma or both have been treated conservatively by photocoagulation, transscleral diathermocoagulation, and cobalt irradiation. These eyes have been enucleated because they showed an enlargement of the residual tumor and, in one case, perforation of the sclera. Cobalt irradiation affected all the layers of the tumor and was innocuous to the sclera. Diathermocoagulation destroyed the deep layers of the tumor and the sclera. Photocoagulation destroyed only the superficial layers of the tumor but not uniformly. Cobalt irradiation is the method of choice and photocoagulation a good adjunct in the conservative treatment of choroidal and ciliary body melanomas.

Choroid↗
PubMed1978

Metastatic tumor of the iris: case report.

The iris involvement in generalized carcinomatosis is less frequent than that of the ciliary body and choroid; its point of interest is that it might constitute the presenting sign of the general disease. The case of a 43-year-old man who had a metastasis of an anaplastic bronchus carcinoma in the iris and died of metastases 3 months after the appearance of the iris tumor, despite adequate chemotherapy, is reported.

Adult↗
PubMed1977

Photoreceptor differentiation in retinoblastomas and its significance in prognosis.

Fleurette is an expression of photoreceptor differentiation and its presence is said to indicate a good prognosis. Twenty-four eyes from 22 cases of retinoblastoma sent to the Mitrani Foundation laboratory between the years 1964 and 1976 were reviewed histologically and clinically. The presence of differentiation in the tumour was not always associated with a good prognosis. The most important prognostic factor seemed to be the length of time the tumour is allowed to remain in the eye. The longer it remains the more undifferentiated the tumour cells become and the greater the probability that it will spread into the choroid and the optic nerve and out of the eye through the sclera and metastasise throughout the body. The presence of gliosis seems to improve the prognosis.

Cell Differentiation↗
PubMed1975

A familial syndrome of central nervous system and ocular malformations.

A family is reported in which three of seven siblings were affected with an association of severe cerebral, cerebellar and ocular malformations. Brain malformations consisted of lissencephaly and the Dandy-Walker anomaly; congenital cataracts, retinal dysgenesis and coloboma of the choroid were found in the eyes. The pathogenesis of these developmental anomalies is probably related to abnormal neuron migration and abnormal closure of fetal fissures, occurring at an early stage of embryonic development. The association of these malformations is unique, and may point to a new malformation syndrome, inherited as an autosomal recessive trait.

Abnormalities, Multiple↗
PubMed1975

Histology of the iris in geese and ducks photosensitized by ingestion of Ammi majus seeds.

Geese and ducks were photosensitized by the ingestion of Ammi majus seeds, and exposure to sunlight. Mydriasis was a characteristic clinical feature of this syndrome in both species. Histologically the iris of the affected birds showed vacuolisation and varying degrees of atrophy of the muscle of the sphincter pupillae. The effect of pilocarpine and physostigmine on the normal and mydriatic eyes was studied. The possible mode of action of photosensitization and the significance of these findings in the light of the use of psoralens in human medicine is discussed.

Animals↗
PubMedDate not supplied

Chronic lesions in geese photosensitized by Ammi majus.

Chronic lesions of the beak, footweb, and eye of geese photosensitized by the comsumption of Ammi majus (L.) are described, 7 weeks after the acute symptoms commenced. Sixty-four (48%) of the 133 birds in the flock showed various degrees of abnormality. All affected birds had stunting of the upper beak and cicatrization and thickening of the footweb. Eighty-nine percent of the affected birds showed ocular involvement, comprising chemosis, blepharoconjunctivitis, keratitis, symblepharon, ankyloblepharon, cicatricial ectropium, and mydriasis.

Animals↗
PubMedDate not supplied

Congenital teratoma of the orbit.

A congenital teratoma of the orbit is described. Histologically, the tissues forming the tumor appeared derived from the three germinal layers and showed an advanced degree of differentiation. An exenteration was performed because of suspicion of malignant tumor in the orbit and because of the severe keratitis with impending perforation which ensued the lagophthalmos.

Female↗
PubMedDate not supplied

Congenital, bilateral, epithelial ingrowth into the anterior chamber.

Interior limbal staphyloma due to epithelial ingrowth into the anterior chamber appeared at birth in both eyes of a brother and sister born successively in a family of eight children. The possible etiopathogeny of such an uncommon occurrence is discussed.

Anterior Chamber↗