From Big Medical Encyclopedia

YELLOW BODY (corpus luteum) — the temporary hemaden developing in an ovary from cells of a granular layer of a follicle after its gap and escaping it an ovum.

Distinguish two look. t. — menstrual and pregnancies. On the structure and stages of development they are identical, the main distinctions are available only in sizes, functional activity and terms of existence. In development. t. distinguish four stages: proliferation, vascularization, blossoming and involution.

The stage of proliferation is characterized by growth of follikulotsit (cells of a granular layer of a follicle) and a hyperemia of an internal cover flow a follicle (tunica interna thecae folliculi). Follikulotsita turn into lyuteotsita (lyuteinovy cells) thanks to accumulation in them of carotene and xanthophyll painting cells in yellow color. Bystry decrease in intra follicular pressure after an ovulation causes a rupture of an internal cover flow a follicle; the blood following at the same time from capillaries mixes up with liquid of a follicle in his cavity. The stage of vascularization is characterized by growing into fabric Zh. t. in the radial direction of capillaries. Both stages of development. t. 3 — 4 days proceed and pass into a stage of hormonal activity — a stage of blossoming. At the same time. t. increases in sizes up to 1,2 — 2 cm, gets crimson coloring and it is a little stuck out over the surface of an ovary. Lyuteotsita are located pleated an internal cover flow. On 7 — the 8th day after an ovulation. t. shows the maximum hormonal activity, produces progesterone and estrogen.

Stage of involution. t. it is characterized by dystrophic changes. Lyuteotsita decrease in sizes, there occurs nuclear pycnosis, hyalinizations, the skladchatost amplifies. t. shrivels. Further, since 12 — the 14th day from the moment of an ovulation, in menstrual. t. full substitution of lyuteotsit is observed by connecting fabric, and approximately by 45th day after an ovulation whitish bodies (corpora albicantia) which are located in the depth of cortical substance of an ovary are formed.

Ovulation (see) and education. t. occur under the influence of the follicle-stimulating and luteinizing hormones of a hypophysis (see. Gonadotropic hormones , Menstrual cycle ).

The menstrual yellow body (corpus luteum menstruationis) functions within 12 — 14 days. At youthful age and in a climacteric functional activity. t. it is reduced, duration of its existence decreases. The progesterone and estrogen emitted. t., provide the correct rhythm of cyclic processes in all organism of the woman and first of all in a uterus. On 7 — the 8th day after an ovulation is observed the maximum increase in progesterone in blood (9,7 ng/ml) and pregnandiol in urine (3 — 5 mg/days). Premenstrual falloff of progesterone causes vascular changes in a mucous membrane of a uterus and rejection of its functional layer. In case of fertilization of an ovum and formation of a zygote the progesterone emitted. t. pregnancies (corpus luteum graviditatis), the rhythm of sokratitelny activity of uterine tubes regulates, and also slows down sokratitelny activity of a uterus and, thus, adjusts the main mechanisms of implantation and early stages of development of a zygote. t. pregnancies begins to increase quickly in sizes, its hormonal activity sharply increases, especially in the first 3 months of pregnancy. The expressed vascularization of its cells is noted, the amount of RNA in them increases. Stage of blossoming. t. proceeds up to 6 months of pregnancy then its involution begins. Main endocrine function Zh. t. from IV month of pregnancy passes to to a placenta (see) and further until the end of pregnancy it is provided with functioning of fetoplacental system.

See also Progesterone , Is oestrogenic , Ovaries .

Bibliography: Gynecologic endocrinology, under the editorship of K. N. Zhmakin, M., 1976; Kvater E. I. Hormonal diagnosis and therapy in obstetrics and gynecology, page 20, M., 1967, bibliogr.

E. I. Kvater, I. S. Rozovsky.