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2018 - 20192
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Subject: Veterinary Anatomy × Start date: 1997 × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    STUDY ON AGEING CHANGES IN THE CORNEA AND RETINA OF BUFFALOES (Bubalus bubalis)
    (SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517502. (A.P.) INDIA, 2019-08) PRASANTH BABU, A; JAGAPATHI RAMAYYA, P (MAJOR); NAGAMALLESWARI, Y; SREENU, MAKKENA; LAKSHMI KAVITHA, K
    The present study was conducted on age related changes in the cornea and retina of buffaloes. A total of 63 samples from three age groups of buffaloes irrespective of their sex were used in this study. The corneal epithelium of buffaloes was nonkeratinized stratified squamous epithelium with 6 to 7 layers at early age and 12-14 layers of cells in adult animals. There were three types of cells noted in the cornea without any distinct boundaries viz., basal cells, intermediate or wing cells and superficial cells. The Bowman’s membrane was a homogenous and acellular layer and its thickness was increased with advancement of age. The stroma of cornea consisted of uniform collagen fibrils and they were loosely arranged in young animals and tightly packed in aged animals. The keratocytes were interposed between the collagen fibers, which were elongated and thick in young animals and thin in old animals. The Descemet’s membrane was a homogenous non cellular fibrous band with dark anterior band zone and light posterior band zone. The corneal endothelial cells were small and firmly adherent to each other in young buffaloes, but they were enlarged and increased in size in old buffaloes. The age related pigmentation was noticed in epithelium and stroma in aged animals. Numerous sub basal nerve plexuses observed in stroma i.e. between the basal cells, wing cells and superficial cells in all age group of animals. All layers of cornea showed moderate to strong reaction for neutral and acid mucopolysaccharides in buffaloes. In scanning electron microscopy study, no apical microvilli on superficial epithelial cells were noted. The Bowman’s layer was consisted of anterior clear zone lamina lucida and posterior dense zone lamina densa. The immunohistochemical reactivity of cytokeratin 3 was noted in the basal cells of corneal epithelium. The reactivity of CD 31 was increased with age in corneal endothelial cells. In the peripheral portion of retina the retinal pigment epithelium was cuboidal and they were packed with melanin pigment. The thickness of RPE was increased and quantity of melanin pigment was decreased with age advancement. In the photoreceptor layer two types of cells were noted i.e. rod and cone cells. They were tightly packed in young age, whereas loosely arranged in older animals. The number of cones progressively increased in number with advancement of age. The nuclei of outer nuclear layer were displaced into outer plexiform layer in the retina of old animals. The outer limiting membrane was continuous throughout the life in the present study. The thickness of outer plexiform layer was increased with advancement of age due to enhancement of synaptic fibers density. The number and density of horizontal, bipolar and amacrine cells were decreased from young to old buffaloes. The thickness of inner plexiform layer was increased with advancement of age due to increased cystoid spaces and thickening of retinal blood vessels between the synaptic fibers of bipolar, amacrine and ganglion cells. The large α and small β ganglion cells were observed in the retina of buffaloes. The number of α ganglion cells were progressively increased with advancement of age. The corpora amylacea and thickened blood vessels were observed in the nerve fiber layer of retina of old buffaloes. The inner limiting membrane was loose and interrupted in young animals whereas, thick and uninterrupted in old buffaloes. The total thickness of retina was decreased form young to adult animals in the present study. The increased number of cone cells, formation of cystoids spaces in the inner plexiform layer, increased size of ganglion cells, hyalinization and thickening of blood vessels in inner plexiform and nerve fiber layers were noticed with advancement of age in buffaloes. In the present study SEM revealed that RPE were tightly packed with rod to spherical and elongated melanin pigment granules in young animals and loosely packed in old buffaloes. Numerous capillaries were observed in the inner nuclear layer. Numerous cystoid spaces were also observed in outer plexiform and nerve fiber layers of retina in old animals. Immunohistochemical studies revealed that PAX6 activity on RPE was decreased with advancement of age in buffaloes. The activity of recoverin on photoreceptor cells and their nuclei and binucleate cells of retina was decreased in old animals. The activity of calbindin was strong to moderate in horizontal and amacrine cells and it’s activity decreased with advancement of age in buffaloes. Retina macula was appeared as strip like and pale in color located dorsal to the optic disc in buffaloes. In the present study macula contained large RPE cells with tightly packed melanin pigment, relatively more number of cone cells, cells of inner nuclear and less cystoid degeneration in inner plexiform and nerve fiber layers was observed when compared to peripheral retina. Further, there was less degenerating changes in the macula when compared to peripheral retina with advancement of age in buffaloes. The ora serrata was a nonsensory portion of the retina which includes pars ciliaris retina and pars iridica retina that cover ciliary body and iris. This region consisted of less number of rod cells, more number of horizontal and amacrine cells and few large ganglion cells were observed when compared to the peripheral retina in the present study. Optic disc was round to oval in shape and in this all retinal layers were gradually disappeared near the optic disc. At the junction of pars optica retina and optic disc RPE cells were small and devoid of melanin pigment. The blood vessels were large near optic papilla and they were small and tiny away from the papilla in buffaloes.
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    ThesisItemOpen Access
    OTOGENESIS IN THE FETUS OF SHEEP (Ovis aries)
    (SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517502. (A.P.) INDIA, 2018-10) KARUNA SRI, VADDI; NAGAMALLESWARI, YAMANI(MAJOR); RAJU, N.K.B.; SREENU, MAKKENA; RAMANI PUSHPA, R.N.
    The present study was undertaken to elucidate the developmental changes in ear. The study was conducted on 60 embryos and fetuses of Nellore sheep between 22 to 145 gestational days. Morphogenesis revealed that five aural hillocks appeared at 23 days fused to form the pinna later. External acoustic meatus (EAM) appeared first at 24 days. Hairs were apparent on EAM by 126 days. Pinna was pendulous and elongated at 145 days. Tympanic cavity presented three tiny ossicles malleus, incus and stapes at the epitympanic region by 63 days. Rostral process of malleus and Lenticular bone were absent in sheep. The ossified part of tympanic ring appeared in semi lunar shape by 55 days. Ossification initiated in vestibule and cochlea by 70 days. Histogenesis revealed small cone shaped pinna at 24 days. Pharyngeal cleft modified into EAM by 39 days and canalized by 49 days. Epithelium of pinna was keratinized at 99 days. The meatal plug appeared first in 24 day embryos and formed primary external auditory canal (EAC) between 31 to 39 days. The ceruminous and sebaceous glands were first identified by 80 days. Middle fibrous layer of ear drum was formed at 126 days. Tympanic membrane appeared trilaminar and EAC was completely canalized by 140 days. Meckel’s and Reichert’s cartilages developed as mesenchymal condensation by 23 days. The distal part of Meckel’s cartilage modified into malleus and incus. Blastemal cells of Reichert’s cartilage modified as stapes. Tubo tympanic recess (TTR) differentiated between 24 to 27 days. Ossification initiated in malleus, incus and stapes at 63, 78 and 80 days respectively. Incudo-malleal and incudo-stapedial joints were established as diarthrodial joints by 80 and 85 days respectively. Eustachian tube lined by psedostratified ciliated columnar epithelium and Meckel’s cartilage disappeared by 85 days. Ossicular ligaments were differentiated at 104 days. The tympanic cavity comprised of fully grown ossified ossicles as adult by 140 days. Otic placode of inner ear differentiated into the otocyst and acoustico-facial ganglion was formed from otocyst by 22 days. Otocyst underwent extensive modification to form semicircular canals, vestibule and cochlea. Endolymphatic duct developed at 23 days. Posterior semicircular duct appeared first than anterior and lateral. The cochlear duct located ventrally within the developing otic capsule during 24 to 27 days. Utriculosaccular chamber (vestibule) differentiated into utricle and saccule with macula utriculi and macula sacculi respectively; Crista ampullaris developed in the ampulla of canal at 31 days. Thickening of epithelium in the cochlear duct formed organ of Corti by 46 days. Cochlea differentiated into scala vestibuli, scala tymapani and scala media at 69 days. The hair cells of organ of Corti matured first in basal turn at 104 days; cochlea was well developed with 21/2 turns indicated the complete inner ear formation as adult in 140 days sheep fetuses.