الفهرس 
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Abstract
This study was carried out on the ovary obtained from 30 clinically healthy Egyptian water buffalo. The specimens were used for the following studies:1- Processing for light microscopy The specimens were routinely processed for paraffin sections: using H & E, Crossman trichorome, Gomori’s reticulin and Periodic acid Schiff. 2- Ultrastructure examination using the transmission electron microscope. A micrometer eye piece was used to measure the thickness of tunica albuginea in different ages. Structure of the ovary The ovaries of the Egyptian buffalo were ovoid in shape and they were formed of stroma and parenchyma. The stroma formed of capsule and interstitial connective tissue while the parenchyma formed of a cortex and medulla.1-Stroma Capsule and interstitial connective tissue The ovary was surrounded by a capsule of dense connective tissue tunica albuginea. Tunica albuginea A thick layer of dense connective tissue called tunica albuginea was found beneath the surface epithelium. Interstitial connective tissue It was formed of closely packed spindle shaped stromal cells and fibers arranged in irregular whorls. Surface epithelium At the ages of one month to 2.5 years old, the surface epithelium was a continuous cuboidal to low cuboidal cell layer. In some areas only at the ages of one month were showed multi-layers (3-5) of large vacuolated cells having thin film of cytoplasm at the periphery. Their nuclei were oval in shape and peripherally located. Extension from these multilayers was observed as tubules entering the cortex. Beginning from 3 years of age this layer showed an interruption of its continuity. At the age of 5 years, the surface epithelium of the ovary was formed of a single interrupted layer of simple squamous cells having darkly stained flattened shaped nuclei. Low cuboidal cells with oval nuclei were sometimes observed. At the ages of 6 years old until 12 years, the surface epithelium was only simple squamous. Cortical tubules and cords formations The surface epithelium invaginated into the ovarian cortex throughout the entire organ. These invaginations appeared as small elongated clefts, subsurface channel-like crypt and solid cords of epithelial cells Oocyte-nest assembly to form new ovarian follicles At the end of the cortical tubules and cords, fragments were observed forming epithelial nests. Oocyte-like cell entered the nest to form a primary ovarian follicle. 2-Parenchyma A-Cortex It was a broad peripheral zone directly underneath the tunica albuginea containing a higher proportion of intercellular substances, and its fibers and cells were arranged more or less parallel to the surface. The cortex contained ovarian follicles embedded in a richly cellular connective tissue. Ovarian follicles A limited number of ovarian follicles within the ovary of Egyptian buffalo were clearly observed. These follicles were located in the cortical stroma either close to the tunica albuginea, in the deep cortex or at the cortico-medullary junction. They were divided into primordial, primary, secondary, tertiary, and large antral follicles.1- Primordial follicles At the age of one month, these follicles were rarely observed with no reserve form the fetal period (prenatal). These follicles were mainly arised from the extended cortical tubules. At the ages of 2.5-5 years, they were very few and singly distributed and declined rapidly in number with the progress of the age to become very rare at the age of 12 years old. The oocyte was spherical or oval in shape and surrounded by one layer of flattened follicular cells By TEM, The flattened granulosa cells were enclosed by the basement membrane. The oocyte nucleus was ovoid to spherical in shape. Few heterochromatin aggregates were attached the nuclear envelope. Zona pellucida was not found but only narrow space was observed in some regions between the oocyte and follicular cells. Follicular cells were in close connection with the oocyte and had flattened spindle shaped nucleus.2- Primary follicles They were very few and located in the outer, mid and deep cortex. The Primary follicles formed from primary oocytes surrounded a single layer of cuboidal follicular cells surrounded by basement membrane. The oocyte had large centrally or eccentrically situated nucleus, darkly stained with clear nucleolus. By TEM, The primary oocyte was surrounded cuboidal granulosa cells. The oocyte nucleus was large centrally or slightly eccentrically located. The ooplasm contained many free ribosomes, sER, many rER and prominent vesicle. Mitochondria were abundant. Zona pellucida appeared as small sized space presented in a few follicles between the oocyte and the surrounding follicular cells. The follicular cells were cuboidal in shape and in close connection with the oocyte. Their nuclei showed more heterochromatin.3- Secondary follicles They were very few. The oocyte had spherical to oval shaped nucleus with several chromatin clumps distributed in the nucleoplasm. The oocyte was characterized by lightly stained acidophilic granular ooplasm with irregular shaped oval nucleus with prominent nucleolus. The theca folliculi was formed from a layer of connective tissue having 1 to 4 cells thick. By TEM, The nucleus was large with dispersed heterochromatin clumps within the nucleoplasm and large, deeply staining three prominent nucleoli. The plasma membrane of the granulosa cells formed numerous microvilli that extend into the space of zona pellucida. Granulosa cells were small with large nuclear/cytoplasmic ratio. The nuclei were irregularly shaped. Spherical and elongated mitochondria and smooth and rough endoplasmic reticulum were the most evident organelles. 4-Tertiary follicles At the age of one month, the ovary showed many tertiary follicles (antral follicles). At the age of 3 years and older ages, they were very few. The follicle showed increase in size and the crescentic shaped antrum divided the granulosa cells into group around the oocyte (cumulus oophorus) and layer of stratified cells lined the antrum and rested on a basement membrane. The tertiary oocyte had spherical shape with fine granular ooplasm and the nucleus was irregular with eccentrically located prominent nucleus. The oocyte was surrounded by relatively thin zona pellucida in the early tertiary follicles which became relatively thick in the late tertiary follicles. The granulosa cells were arranged around the zona pellucida as a complete layer forming the corona radiata. The cells of corona radiata were clearly cuboidal in shape. Theca folliculi was differentiated into theca interna and theca externa. By TEM, The tertiary follicles were characterized by a multilayer of granulosa cells surrounding the oocyte with small spaces between the granulosa cells which were either empty or filled with antral fluid. The oocyte was surrounded by zona pellucid and the granulosa cells were arranged around the zona pellucida forming a complete layer (corona radiata). The cells of corona radiata were cuboidal to low columnar in shape. The cytoplasm contained mitochondria and many free ribosomes. Some spaces were observed between these cells and between these cells and the zona pellucida. 5- Large antral follicle They were very few and approached its maximal size as large vesicle occupied the full thickness of the ovarian cortex and bulged from the free surface of the ovary. The nucleus had irregular shape with granular heterochromatin clumps evenly distributed within the nucleoplasm. The oocyte surrounded by a very thick zona pellucida. There was a thick basement membrane separated the thecal layers from the zona granulosum. The theca interna was composed of large flattened shaped and polyhedral cells with oval nuclei. Theca externa was formed of thin layer of loose connective tissue. By TEM, The granulosa cells had spherical shape rested on thick basement membrane with direct contact or in some areas was separated by small vacuoles. These cells were arranged side by side. They were characterized by large spherical nuclei within fine heterochromatin granules. Cytoplasm contained rough endoplasmic reticulum, mitochondria and secretory granules. B- Medulla was formed mainly of loose connective tissue. The medulla contained many contorted blood vessels and many lymph vessels. Retia ovarii were found in the medulla either as irregular channels or in cords. Corpus luteum is an endocrine gland formed by the remnants of the mature follicle after ovulation and the release of oocyte. It was composed of stroma and parenchyma. After ovulation and the discharge of the liquor folliculi, the wall of the mature follicle collapsed and its granulosa cells lining were thrown into folds and blood clot may be occupied the antrum forming corpus hemorrhagicum. Active corpus luteum formed of granulosa lutein cells and theca lutein cells. Granulosa lutein cells were large cells with a relatively dark acidophilic cytoplasm. The nuclei were either spherical to oval in shape with heterochromatin granules distributed within the nucleoplasm or large euchromatic vesicular nuclei By TEM, The granulosa lutein cells had either heterochromatic nucleus or euchromatic with electron lucent homogenous nucleoplasm packed with granules and associated with two prominent nucleoli. The cytoplasm was closely packed by rounded mitochondria, short granular tubular rER cisternae, more sER, Golgi complex and vacuole. Theca lutein cells, they made up a minor part of luteal tissue and occupied mainly trabecular and peripheral areas. By TEM, The luteal cells had considerable smooth endoplasmic reticulum, rounded mitochondria. The secretory luteal cells undergo autolysis and then will be phagocytosed by macrophages. Fibrosis became conspicuous forming corpus albicans. Atresia One of the major constraints in buffalo reproduction failure was the limited number of follicles and oocyte reserved in the ovary. 1- Primordial, primary and secondary follicles were characterized by degeneration of oocyte followed by granulosa cells. By TEM, the oocyte undergone degeneration followed by changes in the follicular cells. The oocyte was dissoluted with clumped heterochromatin. The flattened granulosa cells surrounding showed nuclear condensation and degeneration. 2- Tertiary and large antral follicles had normal oocyte in which the atretic changes were observed both in the granulosa and the theca layers. But the changes in the granulosa layer were more pronounced than in the theca layers. The stratum granulosum continued to be wrinkled all over the circumstance of the follicle until became completely separated from the glassy membrane then degenerated and transformed into hyalinized material then dissolved leaving empty antrum surrounded by theca interna and theca externa forming vesicular follicles (cystic ovarian disease).