Histological examination of the ovaries of group 1 showed that outside they are covered with a single layer of squamous epithelium (mesothelium), under which is a protein shell. It is built with fibrous connective tissue. In the upper layers of the protein shell fibers and cells are oriented along the oval of the ovary, and the inner layers have circular orientation and without clear boundaries become the cortex. Coat protein is under ovarian cortical substance which is constructed mainly of collagen fibers and stromal cells. As fibers, and cells have a variety of orientations. In the cortex a protein shell single or groups of primary follicles are located in the center of which is located oocyte surrounded by a single layer of follicular cells, which have oval nuclei and a significant amount of light cytoplasm. As the distance from the follicles protein shell their size increases, along with an increase oocyte.

In some places on the ovarian follicles are the primary site separate rounded cavity, the size of which is more than twice the initial follicles. These cavities are formed mutated follicular cells which resemble flat epithelium and are arranged in one or two rows. In these cavities oocytes available, but contains different unit sizes oxyphilous balls. Such formations show that even at the stage of primary follicles in them can pass the destructive processes with the destruction of the oocyte and follicular cells modifications. Primary follicles with the development of increase in size. The oocytes in these follicles also increases significantly, particularly by increasing the volume of cytoplasm, and they are clearly separated from the follicular cells transparent shell. The nuclei of the follicular cells become round or oval and they are surrounded by a considerable amount of light cytoplasm. These cells are arranged in several rows.

With increasing size primary follicles gradually moved towards medulla ovary. In the follicular cells begins to form slit-like first and then rounded shape cavity filled with liquid. Thus the primary follicle is gradually turning to the secondary. Often secondary follicles get irregular elongated or pear-shaped. Around secondary follicles begin to form internal and external folder of connective tissue origin cells.

On the border with the medulla are individual follicles with a cavity 2–3 mm in diameter. Follicular fluid in their uniform, but change is undergoing a follicular layer. Follicular cells in such follicles arranged in 3-5 rows, and follicular fluid, follicular cells adjacent to the observed secretion small balls. Around the area of follicular cells in the rows 20–25 are located inside of the cell folder. Most of these cells are oval or slightly elongated nucleus surrounded by pale cytoplasm. External follicles folder form cells with elongated nuclei, which are located between the collagen fibers. External folder is riddled with small caliber vessels. In some secondary follicles follicular cells along the basement membrane separated from the inner cells and folders filled lumen.

Also follicles in the cortex of the ovary yellow body positioned at different stages of reverse development.

Lutea has different sizes and are more elongated, constitute the basis of their residues follicle cells, cells of internal and external folders between which the winding collagen fibers oriented toward the middle of the corpus luteum. Brain Ovary substance presented different blood vessels mesh size (diameter) located in the stroma of the organ.

In the ovaries of the second group of the protein shell and surface epithelium in structure does not differ from those of the first group.

Under coat protein primary follicles are arranged, but in a somewhat smaller amount. Isolated primary follicles are identified. In our view, it is clearly associated with atresia of primary follicles, as evidenced by the presence of the small size of corpora lutea in the upper layers of the cortex. Some primary follicles receive elongated pear-shaped, and some of them are converted to secondary, to form a cavity filled with fluid. Around the follicle there are well-developed internal and external folder.

Secondary follicles are observed with the cavity of 1.5–2 mm in diameter. In some of them secret and uniform follicular cells arranged in rows 8–9, but the inner layer of follicular cells appear small amount oxyphilous balls of protein origin. In other follicles of the same size, there is a secret oxyphilous large number of balls of different sizes, ie, follicular fluid becomes non-uniform. Follicular layer in such follicles thinner.

In some parts of follicular cells are arranged in 2–3 rows. In our opinion, this may indicate the development of processes atresia vesicular follicles. Thus, in the test ovarian follicle atresia observed at different stages of their development: primary and secondary. In place of these follicles are formed elongated atresial yellow body.

In the ovaries of cows referred to the third group are also follicles at different developmental stages: primary and secondary. But big changes are experiencing secondary follicles. In some follicles follicular vesicular layer is separated from the inner folder cell forms multiple folds that fill the lumen of the follicle. Observed deformed follicles, and such clearance which is completely filled with follicular cells.

Occasionally there are follicles in which follicular layer was subjected to destruction and necrotic follicular cells are separated from the follicular layer and mixed into the follicular fluid that is experiencing deep destructive changes. In the upper layers of the cortex are located a significant number of atresial yellow bodies of different sizes of round or oval shape.

The medulla of the ovary occupies a small area compared to the cut-off area, and is represented by a network of vessels of all sizes, dispersed in the stroma of the organ.

Key words: ovaries, gistostruktura, sexual cycle, follicles, corpora lutea.