Aberrant lacrimal gland development in an anophthalmic mutant strain of rat.
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Visual callosal connections were examined using the horseradish peroxidase (HRP) technique in normal, neonatal and adult C57BL mice, and in adults of this strain which were bilaterally enucleated within 12 h of birth. In addition, callosal connections were also delineated in two strains of congenitally anophthalmic mice, ZRDCT-an and orJ. Material from 129/J mice served as controls for the latter strain. In normal adults anterograde labelling and HRP labelled cells were visible primarily at the borders of area 17. In the 17-18a border region, labelled neurons were located primarily in layers II-III and V. In the medial striate cortex, a small number of labelled cells were present, primarily in lamina VI. Anterograde HRP labelling in the normal adults was also located primarily at the borders of area 17. At the 17-18a border, it was very heavy in layers V and VI, somewhat lighter in layer IV, and fairly dense in layers II-III and the lower half of lamina I. Labelling indicative of anterograde HRP transport was also visible in lowermost lamina V and layer VI across the entire mediolateral extent of area 17. In normals injected with HRP on postnatal day 2 and perfused 24 h later, callosal neurons were distributed throughout the dorsal posterior neocortex, primarily in layers V and VI. Only a very few labelled cells were visible in the supragranular laminae. In adult mice blinded at birth, the zone of callosal cells and terminals extended much further into area 17 than in normals, but aside from the anterograde labelling in layer VI and lowermost lamina V, the medial one-third of the striate cortex was still for the most part devoid of callosal cells and fibers. The laminar distributions of the labelled cells and anterograde transport in the blinded animals were the same as in the normal mice. In both strains of anophthalmic mice the pattern of callosal connections was unlike that in either the normals or neonatal enucleates. In the caudal "visual" cortex, callosal cells and anterograde transport indicative of terminal labelling were visible primarily in the 17-18a border area. Rostrally, however, they were both distributed in multiple (two-three) patches within area 17. Serial reconstructions demonstrated that these patches tended to be aligned in stripes which ran parallel to the 17-18a border. One of these was always located at the 17-18a border, and here the laminar distribution of labelled cells and anterograde labelling was the same as in the normals.(ABSTRACT TRUNCATED AT 400 WORDS)
An inbred kindred showing four cases of autosomal recessive clinical anophthalmia is reported. No association with other congenital malformations or mental retardation was observed.
Clinical and cytogenetic findings in an infant girl with multiple congenital anomalies, principally anophthalmia, are presented. The patient's karyotype was 47,XX,+del(4)(pter leads to q21), the largest partial trisomy of chromosome 4 reported. The possible mechanism of the origin of this abnormality is discussed.
The mouse Small eye (Sey) locus is situated on chromosome 2. Molecular analyses have shown that SeyNeu represents a point mutation leading to a splice site error and loss of the functional gene product. The Sey locus has been shown to be identical with the paired box (Pax)-6 gene, which contains paired-like and homoeobox domains and is a developmental control gene. Pax-6 expression occurs in many parts of the central nervous system during embryogenesis. Therefore, we may expect the Sey mutation to result in abnormal development of the central nervous system. The present study shows that Pax-6 mutation has a bimodal effect upon neurogenesis in mouse: it causes a delay of premigratory neurons in a stage-, region-, and gene-dose-dependent manner. Additionally, Sey mutation impairs axonal growth and differentiation. Neurons of the cortical plate cease differentiation on approximately day 16 of gestation and appear to have increased cohesion: their cytoplasm is swollen and vacuolated. These changes coincide both with reduced formation of axons and with the onset of vacuolar degeneration in existing axons, glial cells and radial glial fibers. Consequently, there is an impairment of the peripheral migration of putative neurons so that the neonatal lesion pattern of the neocortical roof becomes dominated by a broad spectrum of neuronal migration disorders.
The following malformations were observed in a human embryo of 28 mm crown-rump length obtained at operation for tubal rupture in a case of extrauterine pregnancy: 1. Secondary anophthalmia with dysplasia and in part aplasia of the diencephalon. Rudiments of both eyes and eyestalklike proliferations within the diencephalon. No lenses and on the left side only a palpebral fissure. Hypoplasia of the right telencephalic hemisphere and of the right side of diencephalon, mesencephalon and proximal parts of the medulla oblongata. Pseudotumorous proliferations in the diencephalon, in the alar plate of the medulla oblongata (protruding into the fourth ventricle) and in the arachnoid. Hypoplasia of the right internal, middle, and external ear. Dysplasia and in part aplasia of facial osseous elements (cebocephalia). 2. Proximal esophageal atresia with distal tracheoesophageal fistula. 3. A Fallot's tetralogy with right-sided aortic arch and regressive right-sided ductus arteriosus, tricuspid atresia, hypoplasia of the right ventricle with excessive hypertrophy of its wall, and hypoplasia of the pulmonary trunk. Single left superior vena cava and abnormal, semicircular course of the stems of both coronary arteries.
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The dorsal lateral geniculate nuclei (dLGN) of anophthalmic and early postnatally enucleated mice were studied to determine the role retinal fibres play in the differentiation of postsynaptic target structures. Cell counts indicate that retinal fibres are necessary for the development and maintenance of the normal number of dLGN neurons and glia. This retinal fibre dependence is greater for animals enucleated on postnatal day 3 than for animals with a congenital absence of optic axons. Golgi analysis reveals, however, that the lack of retinal fibres does not preclude the development of the thalamo-cortical and intrinsic types of dLGN neuron. Ultrastructural analysis reveals that in anophthalmic and early postnatally enucleated mice, dLGN synaptic sites normally occupied by optic axon terminals become innervated by large terminals containing round synaptic vesicles and mitochondria with an electron dense matrix. Significantly, the formation of these replacement terminals does not seem to depend upon either the previous existence of retinal fibres or the postnatal stage at which retinal fibres are removed. The possibility that some of these large replacement terminals originate from cortical or recurrent collateral axons is considered.
Hydroxyindole-O-methyltransferase (HIOMT) activity for the synthesis of melatonin and 5-methoxytryptophol, both 5-methoxyindoles, was measured in the pineal, the Harderian gland and the retina of the mole rat and in the pineal of the mouse "eyeless". In the pineal and the Harderian gland of the mole rat a larger amount of 5-methoxytryptophol than of the melatonin is synthesized. 5-Methoxyindole synthesis is extremely high in the Harderian gland, whereas in the retina HIOMT activity is low and variable. In the pineal of the mouse "eyeless", a low 5-methoxyindole synthesis showing no circadian rhythm is demonstrated. It is concluded that, besides the generally accepted regulation of the indole metabolism by light, in species with atrophied eyes having Harderian glands (mole rat) and in species without eyes other factors than light might be responsible for the indole metabolism in the pineal gland.
Twenty-four patients with severe anophthalmic orbit syndrome were treated with a combination of techniques utilizing autogenous tissue. Autogenous corticocancellous bone grafts were used in the orbit as a volume filler. The temporalis muscle and a fasciae flap with a pericranial flap were used as a curtain to cover the bone grafts and to give a softening effect. The prosthesis used was a regular eye shell. With this method it can be smaller, thinner, and lighter to produce less deformation of the lower lid, particularly when used for a long period of time. In children who have this deformity compounded by small orbits after oncologic treatment, three-wall orbital enlargement is done to achieve a larger orbit, so as to match the normal unaffected socket and produce symmetry.
A spontaneous congenital deformity is produced in lambs whose dams consume Veratrum californicum on the 14th day of gestation. The deformity is generally expressed as cyclopia, cebocephaly, anophthalmia, or microphthalmia. This teratogenic effect is produced by certain steroidal alkaloid teratogens from the plant - most notably the compound cyclopamine. Cyclopamine is a C-nor-D-homo steroid with fused furanopiperidine rings E and F at right angles to the plane of the steroid because of spiro attachment at C-17 of the steroid. Among veratrum alkaloids, only those with an intact furan ring E were teratogenic in sheep, whereas those in which the peperidine ring is not rigidly positioned at right angles to the steroid were not. Many ruminants and laboratory animals are susceptible to the teratogen. It has wide species and tissue specificity and appears to have a direct effect on the embryo, not as a consequence of metabolic alteration of its structure nor as an indirect effect through a maternal influence. Other plant sources, notably potatoes, tomatoes, and eggplant contain related spirosolane steroidal alkaloids. Among naturally occurring spirosolanes, solasodine is teratogenic in hamsters, but neither tomatidine not diosgenin, the non-nitrogen containing analog of solasodine, is teratogenic. Results of these and other studies suggest that a basic nitrogen positioned alpha with respect to the steroidal plane and at appropriate distance beyond the D ring confers the teratogenicity on the molecule. Potato sprouts with high alkaloid content are teratogenic in hamsters, but tubers and peels are not.
A boy was found to have bilateral anophthalmia at birth. General health examination revealed cryptorchidism and micropenis. Physical and mental retardation in addition to epilepsy were observed. Karyotype showed 47, XY. No report has ever described such a case of dysmorphic syndrome.
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Formation of the neural tube plays a primary role in establishing the body plan of the vertebrate embryo. Here we describe the phenotype and physical mapping of a highly penetrant X-linked male-lethal murine mutation, exma (exencephaly, microphthalmia/anophthalmia), that specifically disrupts development of the rostral neural tube and eye. The mutation arose from the random insertion of a transgene into the mouse X Chromosome (Chr). Eighty-three percent of transgenic male embryos display an open, disorganized forebrain and lack optic vesicles. No transgenic males survive beyond birth. Hemizygous females show a variable phenotype, including reduced viability and occasional exencephaly and/or microphthalmia. Altered or reduced expression patterns of Otx2, Pax6, Six3, and Mrx, known markers of early forebrain and eye development, confirmed the highly disorganized structure of the forebrain and lack of eye development in affected exma male embryos. Physical mapping of the transgene by FISH localized a single insertion site to the interval between Dmd and Zfx on the X Chr. A 1-Mb contig of BAC clones was assembled by using sequences flanking the transgene and revealed that the insertion lies close to Pola1 and Arx, a gene encoding a highly conserved homeobox protein known to be expressed in the developing forebrain of the mouse. Data from Southern blots of normal and transgenic DNA demonstrated that a large segment of DNA encompassing Arx and including part of Pola1 was duplicated as a result of the transgene insertion. From the physical mapping results, we propose a model of the gross rearrangements that accompanied transgene integration and discuss its implications for evaluating candidate genes for exma.
Various alloplastic orbital implants, preferably with a spherical configuration, are employed for the routine care of an enucleated socket. Alternately, an autologous dermis-fat graft can also be used. It represents a safe alternative to alloplastic orbital implants. The method does not require preserved sclera, thus excluding even theoretically possible transfer of pathogens such as viruses or prions in sclera preserved in alcohol. Loss of the transplant or other serious complications were only very rarely observed, late extrusion is unknown. Due to its high degree of safety concurrent with excellent functional and cosmetic results, the dermis-fat transplant is particularly advantageous for young patients. In cases of complicated orbits and contracted sockets the method of dermis-fat transplantation often represents the only promising option.
Over the last 20 years eyeball replacement surgery has improved, especially with the widely accepted use of biocolonisable implants. These implants allow long-lasting biointegration, thus improving prosthesis motility and reducing the rate of postoperative exposure. In this article, we review the chemical structure, toxicity data and manufacturing procedures of the three main commercially available materials: aluminium, hydroxyapatite and porous polyethylene.
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