Textbook of normal histology: including an account of the development of the tissues and of the organs . veal depression, the fun-dus foveae, consists chiefly of the neuro-epithelium. Within acentral area the fovea is devoid of blood-vessels. The ora serrata marks the termination of the optical partof the retina and the transition into its anterior continuations, thepars ciliaris and the pars iridica. The ora is distinguished, inaddition to its irregular serrated border, by the abrupt diminutionin the thickness of the retina, brought about by the sudden termina-tion at this point of many of it
Textbook of normal histology: including an account of the development of the tissues and of the organs . veal depression, the fun-dus foveae, consists chiefly of the neuro-epithelium. Within acentral area the fovea is devoid of blood-vessels. The ora serrata marks the termination of the optical partof the retina and the transition into its anterior continuations, thepars ciliaris and the pars iridica. The ora is distinguished, inaddition to its irregular serrated border, by the abrupt diminutionin the thickness of the retina, brought about by the sudden termina-tion at this point of many of its layers. The regular diminution inthe retinal thickness proceeds gradually from the fundus towardsthe periphery, when, on reaching a point near the ora serrata, manylayers end abruptly, the ciliary continuation measuring only aboutone-third of the thickness of the adjacent retina. ^c8 NORMAL HISTOLOGY. The nerve-fibre and the ganglion-cell layer having already endedbefore reaching the ora, the sudden reduction is caused principallyby the abrupt termination of the two reticular strata. The Fig. Section of human retina through ora serrata : A, B, visual and ciliary portion ofretina; a, vacuoles; b, robust fibres of Muller; c, remains of nuclear layers; d,termination of supporting fibres ; e, transformation of inner nuclear layer into colum-nar cells within continuation of pigment-layer. region of the ora serrata is also noteworthy on account of the re-markable development of the radial fibres of Muller, whichhere occur not only in unusual numbers but also of exceptionalstrength. Beyond the ora serrata the retinal laminae are continued as thepars ciliaris and the pars iridica retinae. These prolongationsconsist of an outer and an inner lamina. The outer layer isthe direct and only slightly modified extension of the retinalpigment; the inner lamina, the attenuated representative of theremaining retinal layers, consists of a single row of slender colum-nar cells, which origin
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Keywords: ., bookauthorpiersolgeorgeageorgea, bookcentury1800, bookdecade1890
