Development of the human sclera
Tóm tắt
Differentiation of the sclera in human embryos and fetuses with a gestation age from 6.4 to 24.0 weeks was studied by light and electron microscopy. The developmental route was found to be anteroposterior and directed from inside outwards. Continuous cytological maturation begins anteriorly during week 7.2 with a loss of free ribosomes and polysomes and an increase in the amount of rough-surfaced endoplasmic reticulum (rER) and Golgi complex components. From the region of the future limbus, these cytodevelopmental events progress posteriorly. By week 13 there are no marked differences between anterior and posterior localization. The cytodevelopmental events directed from inside outwards were found to begin during week 7.2, with a marked increase in the addition of glycogen and lipid droplets in the choroidal half of the anterior scleral condensation and from there progressing to the outer (episcleral) half. With the beginning of week 10.9 no more differences were identified between the outer and the inner portions of the sclera. Portions of the ER denuded of ribosomes close to the plasmalemma were observed during the whole gestational period studied. The role of these structures and the involvement of the Golgi complex for the biosynthesis of collagen are discussed. In week 24, the diameter of the collagen fibrils had increased more than three times in comparison with week 6.4. Elastic microfibrils were found beginning with week 7.2, whereas the elastic deposits with central electron-translucent cores were characterized for the first time beginning with week 18.
Tài liệu tham khảo
Ashhurst DE, Costin NM (1976) The secretion of collagen by insects: uptake of 3H-proline by collagen-synthesizing cells inLocusta migratoria andGalleria mellonella. J Cell Sci 20: 377–403
Avery JK, Han SS (1961) The formation of collagen fibrils in the dental pulp. J Dent Res 40: 1248–1261
Birk DE, Trelstad RL (1984) Extracellular compartments in matrix morphogenesis: collagen fibril, bundle, and lamellar formation by corneal fibroblasts. J Cell Biol 99: 2024–2033
Breyan D, Schilder H (1977) An electron microscopic study of collagen formation in the dental pulp of the human premolar and rat incisor. Oral Surg 44: 437–455
Diegelmann RF, Peterkofsky B (1972) Inhibition of collagen secretion from bone and cultured fibroblasts by microtubular disruptive drugs. Proc Natl Acad Sci USA 69: 892–896
Duke-Elder S, Cook CH (1963) Normal and abnormal development. In: Duke-Elder S (ed) System of ophthalmology, vol 3, part 1. Embryology. Mosby, St. Louis
Ehrlich HP, Ross R, Bornstein P (1974) Effects of antimicrotubular agents on the secretion of collagen. A biochemical and morphological study. J Cell Biol 62: 390–405
Fitzharris TP, Thompson RP, Markwald RR (1979) Matrical ordering in the morphogenesis of tunica media. Tex Rep Biol 39: 287–304
Greenlee TK, Ross R (1967) The development of the rat flexor digital tendon, a fine structure study. J Ultrastruct Res 18: 354–376
Greenlee TK, Ross R, Hartman JL (1966) The fine structure of elastic fibers. J Cell Biol 30: 59–71
Han SS, Avery JK, Hale LE (1965) The fine structure of differentiating fibroblasts in the incisor pulp of the guinea pig. Anat Rec 153: 187–210
Hay ED (1958) The fine structure of blastema cells and differentiating cartilage cells in regenerating limbs of Amblyostoma larvae. J Biophys Biochem Cytol 4: 583–591
Hay ED, Dodson JW (1973) Secretion of collagen by corneal epithelium. I. Morphology of the collagenous products produced by isolated epithelia grown on frozen-killed lens. J Cell Biol 57: 190–213
Hogan MJ, Alvarado JA, Wedell JE (1971) Histology of the human eye. Saunders, Philadelphia
Jones AW, Barson AJ (1971) Elastogenesis in the developing chick lung: a light and electron microscopical study. J Anat 110: 1–15
Kanai A, Kaufman HE (1972) Electron microscopic studies of the elastic fiber in human sclera. Invest Ophthalmol 11: 816–821
Karrer HE (1960) Electron microscope study of developing chick embryo aorta. J Ultrastruct Res 4: 420–454
Kelemen E, Janossa M, Calvo W, Fliedner TM (1984) Developmental age estimated by bone-length measurement in human fetuses. Anat Rec 209: 547–552
Mann I (1964) The development of the human eye, 3rd edn. Grune & Stratton, New York
Marchi F, Leblond CP (1983) Collagen biogenesis and assembly into fibrils as shown by ultrastructural and 3H-proline radioautographic studies on the fibroblasts of the rat foot pad. Am J Anat 168: 167–197
Merker HJ, Struwe K (1971) Elektronenmikroskopische Untersuchungen zum Problem der Sekretion der bindegewebigen Interzellularsubstanz. Cell Tissue Res 115: 212–225
O'Rahilly R (1975) The prenatal development of the human eye. Exp Eye Res 21: 93–112
Ozanics V, Rayborn M, Sagun D (1976) Some aspects of corneal and scleral differentiation in the primate. Exp Eye Res 22: 305–327
Revel JP, Hay ED (1963) An autoradiographic and electron microscopic study of collagen synthesis in differentiating cartilage. Cell Tissue Res 61: 110–144
Rohr H (1965) Die Kollagensynthese in ihrer Beziehung zur submikroskopischen Struktur des Osteoblasten (elektronenmikroskopisch-autoradiographische Untersuchung mit Tritium-markiertem Prolin). Virchows Arch [A] 338: 342–354
Ross R, Benditt EP (1965) Wound healing and collagen formation. V. Quantitative electron microscope radioautographic observations of proline-H3 utilization by fibroblasts. J Cell Biol 27: 83–106
Salpeter MM (1968) H3-Proline incorporation into cartilage: electron microscope autoradiographic observations. J Morphol 124: 387–422
Schwarz W (1953) Elektronenmikroskopische Untersuchungen über die Differenzierung der Cornea- und Sklerafibrillen des Menschen. Cell Tissue Res 38: 78–86
Spitznas M (1971) The fine structure of the human scleral collagen. Am J Ophthalmol 71: 68
Spitznas M, Luciano L, Reale E (1970) Fine structure of rabbit scleral collagen. Am J Ophthalmol 69: 414–418
Spitznas M, Luciano L, Reale E (1971) The fine structure of the rabbit sclera with special reference to a peculiar structure in the fibroblast rough surfaced endoplasmic reticulum. Cell Tissue Res 118: 439–448
Torczynski E (1982) Sclera. In: Jakobiec FA (ed) Ocular anatomy, embryology, and teratology. Harper & Row, Philadelphia, pp 587–599
Trelstad RL (1971) Vacuoles in the embryonic chick corneal epithelium, an epithelium which produces collagen. J Cell Biol 48: 689–694
Weale RA (1982) A biography of the eye. Lewis, London
Weinstock M (1972) Collagen formation — observations on its intracellular packaging and transport. Cell Tissue Res 129: 455–470
Weinstock M, Leblond CP (1974) Synthesis, migration, and release of precursor collagen by odontoblasts as visualized by radioautography after [3H] proline administration. J Cell Biol 60: 92–127