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2014 - 20182
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Subject: Veterinary Anatomy × Author: KARUNA SRI, VADDI × End date: 2019 ×
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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.
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    ThesisItemOpen Access
    HISTOMORPHOLOGICAL CHANGES IN THE TESTIS OF RATS EXPOSED TO METHYL MERCURY IN RELATION TO PITUITARY-TESTICULAR AXIS
    (SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI – 517 502. (A.P) INDIA, 2014-10) KARUNA SRI, VADDI; NAGAMALLESWARI, Y(MAJOR); KISHORE, P V S
    ABSTRACT: This study was conducted on 36 adult male Sprague Dawley rats of 6 weeks age. These subjects were randomly assigned into three groups, viz. control (group I), 2.5ppm methyl mercury exposure (group II) and 5.0ppm methyl mercury exposure (group III). Methyl mercury was fed in the form of methyl mercuric chloride in drinking water daily. There was a significant increase in body weight in the 5.0ppm group than in the 2.5ppm and control groups at 35 days of exposure. Elongated bean shaped testes were present. The average total testes weight also increased significantly in both the treated groups than in the control group at 35 days post exposure. The average length and width of both right and left testes increased in 2.5 and 5.0ppm groups when compared to the control at 14 days of exposure. In the high dose (5ppm) group there was a significant increase in the average width of the right and left testis compared to the control at 35 days post exposure. The length and width of the left testis in both exposure groups was significantly increased.There was a significant increase in the mean sperm count in rats of 2.5ppm group than in other groups at 14 and 35 days post exposure. The average number of head and tail abnormalities also increased in both treated groups during the same period. The average serum total testosterone level increased significantly in the 5.0ppm group than in 2.5ppm and in the control groups at 14 days post exposure. However, there was no significant increase in the serum total testosterone level among all the three groups at 35 days post exposure.The thickness of tunica albuginea (capsule) of testis was reduced in both the treated groups (2.5 and 5.0ppm) at 14 and 35 days post exposure. A potential space was seen between the basal and adluminal compartments at 14 days post exposure in both the treatment groups. No potential space was observed in the control group. Hypertrophy and vacuolation of sertoli cells were present in both the treated groups at 14 and 35 days post exposure. Normal cohort of 5-6 types of cell arrangement was lost in both the treated groups at 14 and 35 days post exposure. Mitotic divisions were seen in the group given 5ppm at 14 days post exposure and in both the treated groups at 35 days post exposure. Thinning and degeneration of the peritubular membrane was found in both treatments at both the exposure periods. Altogether, the above changes lead to disruption of blood-testis barrier. Hypertrophy and vacuolation of leydig cells were observed in the interstitium of testis in both the treatment groups compared to the control at 35 days post exposure.The average weight, length and width of pituitary glands increased in both treated groups compared to the control and it was statistically significant at 14 days post exposure. Hypertrophy of B1 (LH cells) and B2 (FSH cells) was observed in the treated groups of both exposures compared to the control. B2 cells were present in clusters at the postero-lateral aspect of pars distalis. Some cells showed a centrally placed nucleus while others had a peripheral nucleus. Vacuoles were present on the apical surface of nucleus which might represent the Golgi complex in the 2.5ppm group. This might be an indication of the secretory state of cells. No vacuoles were found in the control group. Hypertrophy of sub capsular capillaries was observed at the periphery of pars distalis.