Morphological study on the human developing vitreous collagen fibrils and persistent hyperplastic primary vitreous

The human primary vitreous fibrils were similar to the secondary vitreous fibrils on electron microscopic observation. On the other hand, the intravitreal strand in a persistent hyperplastic primary vitreous (PHPV) contained large numbers of collagenous fibrils with 40-50 nm diameters and about 65 nm cross-striation periodicity. Besides these, other types of noncross-striated fibrils, ranging in diameter from 10 to 30 nm were observed in the circumferential region of the intravitreal strand. Moreover, there was complete morphological continuation between the intravitreal strand and the optic disc. Their histochemical properties were very likely collagenous and in part glial. Although the results are based only on 1 case of PHPV, present observations showed that components of the intravitreal strand of PHPV considerably differed from the primary vitreous.     

Electron microscopic study of the developing human vitreous collagen fibrils

Vitreous fibrils, and collagen fibrils in other ocular tissues, were observed in 5-, 6- and 7-weeks human embryos. The vitreous fibrils in 7-weeks embryos were distinctly different from the fibrils of other ocular tissues. The vitreous fibrils near the rim of the optic cup were similar to the fibrils in the anterior cavity of the lens vesicle in the 6-week embryo. Broad fibrils were demonstrated with a diameter of 30-40 nm and a striated banding pattern of about 60 nm periodicity.     

Glycosaminoglycan and collagen distribution in the developing human vitreous

· Background: We determined the distribution of glycosaminoglycans and collagens in the developing human vitreous. · Methods: Eighty human eyes from 5 gestational weeks to 2 postnatal years of age were used. Glycosaminoglycan components were determined by enzyme digestion with hyaluronidase or chondroitinase AC and ABC and immunohistochemistry for chondroitin, chondroitin-4-sulfate, chondroitin-6-sulfate, and dermatan sulfate. Collagen distribution was determined by immunohistochemistry for types I, II, and III collagens. · Results: Enzyme digestion showed that throughout development hyaluronic acid is the main glycosaminoglycan in the vitreous and in the extraocular space at 5–7 gestational weeks. Both areas were filled with mesenchymal cells. Immunohistochemistry showed chondroitin-6-sulfate in the vitreous between 6 and 40 gestational weeks, and chondroitin-4-sulfate between 12 and 40 gestational weeks. Hyaluronic acid and chondroitin sulfate appeared in the retina and around the hyaloid vessels at 12–40 weeks. Immunohistochemistry showed type III collagen in the vitreous and around the mesenchymal cells at 5–7 weeks that was replaced by type II collagen after 8 weeks. · Conclusions: Hyaluronic acid is the major glycosaminoglycan in the vitreous throughout development, except for the transient appearance of chondroitin sulfate at 6–40 gestational weeks. Type III is the main collagen in the early developing vitreous that converts to type II collagen at 8 weeks. The primary and secondary vitreous has the same components as these macromolecules. These vitreous glycosaminoglycans and collagens seem to be produced by mesenchymal cells at an early stage and by the retina and hyaloid vessels during middle and late development. Received: 7 November 1997 Revised version received: 5 January 1998 Accepted: 7 January 1998     

人眼玻璃体黏度的研究

目的 了解眼玻璃体的流变学特点。方法 在37℃低剪切条件下用瑞士产的旋转黏度仪测定尸体眼玻璃体黏度。结果 尸体眼玻璃体表现出非牛顿流体的特性;黏度随剪切率而变化。上升曲线与下降曲线不重合说明有弹性滞后,存在残余应力。这种性质在低剪切时表现得更明显,年龄与黏度负相关,P=0.005,r=-0.8045。结论 玻璃体是一种非牛顿流体,存在着年龄相关的玻璃体液化。     

Morphological study on glucocorticoid-induced cataract in developing chick embryo

Nishigori et al. reported a transient cataract model after administering glucocorticoid to a 15-day-old chick. Biochemically, the mechanism of onset of this cataract was thought to be related to damage caused by the formation of oxidative stresses and by a protein-water phase separation. There appear to be no reports on changes in the fine structure. After hydroocortisone succinate sodium was administered to 15-day-old chick embryos, the lenses were removed at 12, 24, 30, 48, 72 and 96 h and put in 4% gluraldehyde. The specimens were examined by light, transmission and scanning electron microscopy. Twelve to 24 h after administration to chick embryos, lens fibers containing electron-dense cytoplasm began to appear in the bow area of the equator and were still present thereafter. Thirty to 48 h after administration, numerous vacuoles of varying sizes began to appear in the lens in sites corresponding to the opaque region. These vacuoles, ranging from 2 to 8 m in diameter, were distributed in the intercellular spaces between the lens fibers. The vacuoles had disappeared by 96 h after administration, but during that period, the height of the epithelial cells in the equatorial region and the elongation of the equatorial lens fibers had become irregular. Transient opacity was due to the presence of vacuoles of various sizes, occurring in the intercellular space between the lens fibers around the lens nucleus. Moreover, the effect of glucocorticoid administration was noted in the lens epithelium and the lens fibers in the equatorial region.     

Electron microscopic observation on the developing rabbit and human vitreous collagen fibrils by negative staining

The vitreous fibrils of developing eyes of 3-day-old rabbits and 24th week human fetuses were examined by the negative staining method (phosphotungstic acid) electron microscopically. Fibrils about 10 nm in diameter and with no periodic striated pattern as well as adult ones were observed. Peculiar fibers were observed in both vitreous samples preserved at low temperature. Particularly, dimeric segment-long-spacing (SLS) aggregates and fibrous-long-spacing (FLS)-like aggregates were observed in 3-day-old rabbit vitreous. FLS-like aggregates showed a 125-nm light band and 50-nm dark band periodic pattern and seemed to be formed with 300-nm overlapping of dimeric SLS aggregates. The present results indicate that the developing vitreous could possibly form various types of collagen fiber under native conditions.     

Degradation of glycosaminoglycans by extracts of calf vitreous hyalocytes

The ability of extracts of calf vitreous hyalocytes to catalyze the degradation of glycosaminoglycans was studied by incubation with radioactively labeled substrates. The degradation of the polymeric substrates to lower molecular weight products was assayed by three methods: (1) paper chromatographic separation of low molecular weight, mobile digestion products from undigested, high molecular weight material which remains at or near the origin; (2) loss of the ability of the glycosaminoglycan to be precipitated by cetylpyridinium chloride; (3) gel chromatography to separate low molecular weight digestion products, which appear in the retarded volume, from undegraded, high molecular weight material, which is eluted in the void volume. The acidic pH optimum of the reaction suggests a lysosomal origin of the enzyme activity.     

Morphological and histochemical studies of goblet cells in developing human conjunctiva.

This study deals with the development of the human conjunctival goblet cells. Fifty-six eyes of human embryos and fetuses ranging from 5 to 41 weeks of gestational stage were used. The distribution of glycosaminoglycans in the goblet cells was investigated with 1% alcian blue (pH 2.5) staining. For identifying the types of glycosaminoglycans, enzyme digestion methods were carried out with streptomyces hyaluronidase, chondroitinase AC, chondroitinase ABC, or sialidase (neuraminidase). At 9 weeks of gestational age, goblet cells appeared in the fornix region of the conjunctiva and extended toward the palpebral and bulbar regions. Histochemical studies with enzyme digestion methods revealed the existence of sialomucin in the goblet cells from 9 weeks. This finding suggested that the goblet cells first appeared in the fornix area, extending toward the palpebral region, then toward the bulbar region, and containing sialomucin from their early stage of development.     

人玻璃体膜及视网膜前膜免疫组化研究

目的 鉴定人玻璃体膜及视网膜前膜的细胞成分。方法 对增生性玻璃体视网膜病变（ＰＶＲ）１２例和外伤性ＰＶＲ８例患者经玻璃体手术取出的增生膜标本,用鼠抗人角蛋白、波形蛋白、神经胶质纤维酸性蛋白（ＧＦＡＰ）和ＣＤ１４等４种单抗做免疫组织化学ＡＢＳ法染色并观察。结果 １２例ＰＶＲ膜抗角蛋白染色均为阳性,６例抗ＧＦＡＰ阳性,１０例抗ＣＤ１４阳性;８例外伤性ＰＶＲ膜２例抗角蛋白染色阳性,７例抗ＧＦＡＰ阳性,３     

Vascular remnants in the rabbit vitreous body. I. Morphological characteristics and relationship to vitreous embryonic development

Using light and transmission electron microscopy, we observed novel structures in the rabbit vitreous body. They were found in 18 out of 27 eyes from rabbits 0.5-36 months of age. These structures are scattered throughout the entire vitreous matrix. By light and transmission electron microscopy, they appear to be made up of the same structural components. Based upon their morphological appearance, they can be subdivided into two groups which we provisionally named 'intravitreal structure type 1 and 2' or 'IVS-1' and 'IVS-2'. IVS-1 has a highly variable morphology (e.g. star-shaped, round, oval), whereas IVS-2 is tubular. The dimensions of IVS-1 vary in relation to the mesh diameters of the collagen matrix, while those of IVS-2 do not. In adult rabbit eyes, we observed transitions between IVS-1 and intravitreal ghost vessels (acellular remnants of blood vessels), and between IVS-1 and IVS-2. In very young rabbits (14 days) we observed intravitreal ghost vessels consisting of tightly-packed IVS-1. Therefore, we concluded that IVS-1 and 2 are related structures presumably of vascular origin. It appears that they represent fragmented and non-fragmented acellular remnants of hyaloid blood vessels. The presence of vascular remnants throughout the entire vitreous matrix of adult rabbit eyes is in conflict with existing theories on the embryonic development of the vitreous body, which describe a strict spatial separation between the primary (vascular) and secondary (avascular) vitreous. However, it strongly supports an alternative theory that explains the formation of the secondary vitreous by a process of continuous remodelling of the primary vitreous.