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ЗмістClinical anatomy and physiology of the female genital organs
External female genital organs
Internal genital organs
The uterine isthmus (fig. 3)
Ligaments of the uterus
Blood supply of the genital organs
Pelvic cellular spaces
Physiology of the female genital organs
Regular menstrual cycle is a sign of normal function of female reproductive system.
Regulation of menstrual cycle
Cyclic changes in uterine tubes
Biological action of the ovarian sex steroids and gonadotropins
Methods of examination in gynecology
1Uterine cervix, its size, shape (cylindrical, conic), shape of external os (round in nonparous women, fissured in parous ones)
Objectives: to learn clinical anatomy and physiology of the female genital organs.
Professional motivation: clinical anatomy of the genitals has a great value for studying gynecology. The structure of external and internal genitals, their blood supply enables to understand pathogenesis of gynecologic diseases.
1. Eexternal female genital organs
2. What specialist consults women with patology of the female genital organs?
3. How often can medical conditions complicate the course of pathology of the female genital organs?
STUDENTS' INDEPENDENT STUDY PROGRAM
I. Objectives for Students' Independent Studies
You should prepare for the practical class using the avaible textbooks and lectures. Special attention should be paid to the following:
1 - Eexternal female genital organs.
2- Internal female genital organs.
3- Normal menstrual cycle.
4. Physical examination.
5. Methods of functional diagnostics
Key words and phrases: female genital organs .
ANATOMY OF THE FEMALE GENITAL ORGANS
The female genital organs are considered to be external and internal. They are separated by hymen (fig. 1.)
Fig. 1. External female genital organs:
To external female genital organs (genitalia externa, vulva) belong: mons pubis, labia majora, labia minora, clitoris and vaginal vestibule.
Mons pubis (mons pubis) is the fatty cushion that lies over the anterior surface of the symphysis pubis. There is no hair on the mons pubis before puberty. In females the skin of the mons pubis is covered by curly hair that forms thefemale linea horizontales. During menopause the hair becomes thick. If the hair growth on linea alba is up to the umbilicus, and covers inner thighs it indicates the functional disorders of the ovaries or adrenal glands.
Labia majora (labia majora pudendi) are two protruding folds of skin with adipose tissue, that enclose the pudendal cleft. They extend downward and backward from the mons pubis up to posterior fourchette where they join.
The region between the posterior fourchette and anus is called obstetric perineum. Its height in most women is 3-4 cm. If it is more than 4 cm it is called high perineum and if it is less than 3 cm it is called low perineum. The skin and muscles of this region may tear during delivery and then the structure of pelvic floor becomes abnormal. It is the pubococcygeus, the main part of the levator ani, that is usually torn. Weakening of the levator ani and pelvic fascia resulting from stretching or tearing during childbirth may alter the position of the neck of the bladder and urethra. These changes can cause urinary stress incompetence, characterized by dribbling of urine when intraabdominal pressure is raised during coughing and lifting, for instance.
Major vestibular glands. Bartholin's glands are a pair of small compound glands about 0,5-lcm in diameter, each of which is situated beneath the vestibule on either side of the vaginal opening. The Bartholin's glands lie under the constrictor muscle of the vagina and sometimes are partially covered by the vestibular bulbs. These are alveolar-tubular glands secreting mucus into the vestibule during sexual intercourse, and their ducts open into the fissura just between the labia minora and hymen. Bartholinitis is an inflammation of the vestibular glands, which may result from the number of pathogenic organisms. Bartholin's glands are often the site of gonococcal infections and. Due to the pathogen the external orifices of the Bartoline ducts become hyperemic.
Labia minora (labia minora pudendi) are two flat reddish folds, visible when the labia majora are disclosed (the junction of the labia minora on the ventral surface is called frenulum). The labia minora may vary from scarcely noticeable structures to leaf-like flaps measuring up to 3 cm in length. The labia minora extend from the clitoris laterally around the external urethral orifice and the orifice of the vagina. They are extremely sensitive and are supplied with a variety of nerve endings.
Clitoris (clitoris) is a small cylindric erectible body located at the superior part of the vulva. The clitoris is composed of glans, body and two crura. The glans is richly supplied with nerves and is therefore extremely sensitive to touch. The clitoris is erogenous organ of women.
Vaginal vestibule (vestibulum vagina) is the space between the labia minora laterally and extending from the clitoris above to the comissura posterior below. It is usually perforated by six openings: the urethra, the vagina, the two Bartholin glands, the ductus of the two paraurethral glands, also called as Skene's ducts.
Urethra (urethra) is approximately 4 cm long and 6 mm in diameter and lies immediatly above the anterior vaginal wall and terminates externally at the urethral orifice. The urethral orifice is 2-2,5 cm below clitoris. Urethra has external and internal sphincters.
Hymen is a thin fold of mucous membrane surrounding the vaginal outer in virgin women. The hymen may take many forms, such as a cribriform plate with many small openings or a completely inperforated diaphragm (in this case it must be removed to allow menstrual outflow). The openings in the hymen are usually greatly enlarged during the first sexual intercourse. In nulliparous hymen is represented by a circle of carunculae hymenalis, and after childbirth a circle of carunculae myrtiformes.
The female internal organs include vagina, uterus, uterine tubes and ovaries (fig. 3).
Vagina, a musculomembranous tube (8-1 Ocm long) extends from the uterine cervix to the vestibule of the vagina (cleft between the labia minora). The superior end of the vagina surrounds the cervix. The vaginal vault is subdivided into anterior, posterior and two lateral fornices. The posterior fornix is the deepest part and it is closely related to the cul-de-sac. It allows easy access to the peritoneal cavity from the vagina by either culdocentesis or colpotomy. Vagina lies posteriorly to the urethra and urinary bladder and anteriorly to the rectum.
The vagina layers: the mucosa of the vagina is composed of non keratinizing stratified squamous epithelium (fig. 2). Beneath the epithelium there is a thin fibromuscular layer; an inner circular layer and an outer longitudinal layer of smooth muscle can be identified. A thin layer of connective tissue overlying the mucosa and muscularis layer is rich in blood vessels and a few small lymphoid nodules drain there. Normally, glands are not present in the vagina.
Vaginal secretions appear as a result of liquid' exudation from lymphatic and blood vessels and also at the excessive cervical glands mucus. Vagina of healthy woman has a small amount of white colour disharge. The acidic reaction is owing to lactic acid which is produced from the breakdown of glycogen in the mucosa by lactobacilli.
Concentration of lactic acid within vagina is 0, 4%. It liquidates pathogenic microorganisms that may enter into vagina from outside. This process is called vaginal "self cleaning".
Vaginal "self cleaning" is possible due to normal ovarian function. Only estrogenic hormones affect maturation of epithelial cells of mucous membrane and glycogen synthesis. Glycogen is the material for lactobacilli. The pH of vaginal secretion in adult women ranges between 4,0 and 5,0. Ovarian dysfunction leads to alcaline reaction of vaginal secretions. As a result of this pathogenic bacteria and fungi may grow in the vagina and provoke inflammatory process of vagina called vaginitis.
Such term as vaginal "self cleaning" characterises vaginal flora.
There are four stages of vaginal secretions "self cleaning". They are:
vaginal "self-cleaning" doesn't allow pathogenic microorganisms to enter the uterus.
Uterus (hystera) is a thick-walled, hollow muscular pear-shaped organ, somewhat flattened anterposteriorly.
The uterus is approximately 7.5 cm long, 5 cm broad, 2 cm thick and weighs 50-100 grams. In the postpuberal women two third is body and one third is cervix. During childhood and postmenopause body and cervix are approximately of equal length.
Uterus consists of the body and the cervix. Body forming the upper two third has two parts. The frontal plane has a triangle form. The base of triangle is fundus uterus. It's apex is the internal orifice. The angles of the triangle arc the internal orifices of the Fallopian tubes. The posterior and anterior walls of the uterus touch each other, that's why uterine cavity is rather a narrow hollow/
^ represents a transitional area where the endo-cervical epithelium gradually changes into the endometrial lining. In this region the cezarean section is made.
Fig. 3. Uterus, fallopian tubes, ovaries, vagina (sagittal section):
1 — fundus of uterus; 2 — uterine cavity; 3 — ovarian ligament; 4 — fallopian tube
5 — ovary; 6 — round ligament; 7 — broad ligament; 8 — uterine cervix
9 — cervical canal; 10 — vaginal wall; 11 — uterine artery
12 — infundibulopelvic ligament (suspensory ligament)
The cervix is from 2 to 3 cm in length. The portion that protrudes into the vagina and is surrounded by the fornices is covered with a keratinizzed stratied squamous epithelium. At about the external cervical os the squamous epithelium covering the exocervix changes to simple columnar epithelium, the site of transition being referred to as squamocolumnar junction. The cervical canal (fig. 5) is lined by irregular, arborized, simple columnar epithelium which extends into the stroma as cervical "glands" or crypts.
The cervical canal is fusiform and opens at each end at the internal os and external os.
The wall of the body of the uterus is composed of three layers: serosa, muscular and mucosa. The inner layer of the uterus is the mucosal layer, which lines the uterine cavity in nonpregnant women. It is called the endometrium. This lining of the uterine corpus may vary from 2 to 10 mm in thickness, depending on the phase of the menstrual cycle. The endometrium is composed of surface epithelium, glands and interglandular mesenchymal tissue containing numerous blood vessels.
Fig. 4. Schematic correlation between uterus, fornices and peritoneum in normal position of the uterus:
5 I — body of uterus; II — isthmus of uterus
III — cervix of uterus; 1 — peritoneum; 2 — anatomic internal uterine ostium; 3 — histological uterine ostium 4 — posterior fornix; 5 — cul-de-sac (rectouterine pouch) 6 — urinary bladder; 7 — vagina
10 — vesico-uterine pouch
The myometrium is quite thick, consists of smooth muscles and has three layers: external (longitudinal), medial (circulative), internal (longitudinal). In the body of the uterus the muscular layer has more circulative fibers and cervix contains longitudinal, therefore cervix is more rigid and less contractile than the whole uterus.
The perimetrium (serous coat) of the uterus is the peritoneum, only the upper portion of the anterior wall of the uterus is covered by serosa; then the bladder is covered and forms the vesicouterine pouch (excavatio vesico-uterina); almost the entire posterior wall of the uterus is covered by peritoneum, the lower portion of which forms cul-de-sac or rectouterine pouch of Douglas (excavatio recto-uterina).
Normally the uterus is anteversio (with the body of the uterus tipped slightly anteriorly) — tipped anterosuperiorly relative to the axis of the vagina and anteflexed (the uterine body is flexed or bent anteriorly relative to the cervix).
The position of the uterus changes with the degree of filling of the bladder and rectum. The angle between the axis of the body and the cervix varies from anteflexion to retroflexion, and normally is near 120°.
Functions of uterus:
Uterine tubes (tubae uterinae) or fallopian tubes extend from the uterus to the site near the ovaries and provide access for the ovum to the uterine cavity.
Each tube is divided into interstitial portion, isthmus, ampulla and infundi-bulum. The uterine tube varies considerably in thickness; the narrow portion of the isthmus measures from 2-3 mm, and the widest portion of the ampulla measures between 5 and 8 mm in diameter. The opening of the infundibulum is surrounded by a number of long thin processes called fimbriae. The wall of each uterine tube consists of three layers: the external serosa is formed by the peritoneum, the middle muscular layer consists of longitudinal and circular smooth muscle fibers and the innner mucosa consists of a mucous membrane of simple ciliated columnar epithelium. Tubal peristalsis depends on the menstrual cycle and is believed to be important factor in transport of the ovum. The ciliated epithelium helps to move the ovum through the uterine tubes (fig. 6, 7)
Functions of the uterine tubes:
^ are almond-shaped organs. They provides the double function. The ovaries work as endocrine glands (produce estrogens and progesteron). The ovaries provides the ovums maturing.
The sizes of ovaries are 4x2x1 cm. Each is attached to the posterior surface of the broad ligament by a peritoneal fold called the mesovarium. Two other ligaments are attached to the ovary: the suspensory ligament extends from the mesovarium to the uterine body wall and the ovarian ligament attaches the ovary to the superior margin of the uterus. The ovarian arteries, veins and nerves pass within the suspensory ligament and enter the ovary through the mesovarium.
Occasionally the mesosalpinx between the uterine tube and the ovary contains: the epoophoron is formed from the remnants of the mesonephric tubules — the transistory embrionic kidney; the paroophoron may accumulate fluid and form cycts.
The layers: externally the ovaries are covered by the ovarian epithelium or cuboidal cells. Just below the epithelium the tunica albuginea surrounds the ovary. The ovary is divided into outer portion called the cortex and inner portion called medulla. Blood vessels, lymph vessels and nerves from the mesovarium enter the medulla. In cortex the ova and graafian follicles are located (fig. 8).
Fig. 8. Ovarian section:
producing of sexual hormones — is its endocrine function
follicular development and ovulation — is its generative function
if fertilization occurs, the corpus luteum persists and secrets large amounts of
progesterone. This insures a normal duration of the first trimester of pregnancy
The uterus is a dense structure located in the centre of the pelvic cavity. This position is provided by the supportive, suspensive and fixative apparatus of the uterus.
Suspensive apparatus of the uterus:
The infundibulopelvic (suspensory) ligament of the ovary extends from the upper (tubal) pole to the pelvic wall; the ovarian vessels and nerves pass through it. Fixative apparatus of the uterus is composed of:
In addition to the ligaments much support is provided inferiorly to the uterus by the skeletal muscles of the pelvic diaphragm. If these muscles are weakened (e.g. because of childbirth), the uterus can descend inferiorly to the vagina. This condition is called as uterine prolapse.
Fixative apparatus of the uterus are the pelvic diaphragm muscles.
The external genital female organs are supplied by branches from internal pudendal artery (a.pudenda interna) and partly from iliac arteries. Internal pudendal artery is the anterior branch of internal iliac artery.
The vascular supply of internal genital organs (fig. 9,10). The uterine artery is the main branch of the anterior division of the internal iliac or hypogasric artery. It descends for a short distance, enters the base of the broad ligament and makes its way medially to the side of the uterus. Reaching the side of the cervix, the uterine artery is divided into a large superior branch that supplies the body and fundus of the uterus and a smaller vaginal branch that supplies the cervix and upper third of vagina.
The ovarian artery arises from the abdominal aorta inferior to the renal artery (sometimes left ovarian artery arises from renal artery). It is divided into ovarian and tubal branches that supply the ovary and uterine tube. These branches anastomose with the branches of the uterine artery.
The vaginal veins form vaginal venous plexuses along the sides of vagina. These veins are continuous with the uterine venous plexux as the uterovaginal venous plexus and drain into the internal iliac veins through the uterine vein.
The vulva contains a rich network of lymphatic vessels that pass laterally to the superficial inguinal lymph nodes. The vaginal lymphatic vessels drain into the internal and external iliac lymph nodes and to the sacral and common iliac nodes.
The uterine lymphatic vessels follow three main routes. Most vessels from the fundus pass to the lumbar lymph nodes, but some vessels pass to the external iliac lymph nodes.
Vessels from the uterine body pass within the broad ligament to the external iliac lymph nodes.
Vessels from the uterine cervix pass to the internal iliac and sacral lymph nodes.
. 10. Principal arterias of the genital organs:
Innervation of the genital organs
The nerve supply of the genital organs is derived from superior and inferior hypogastric plexus. Uterus has the sympathetic innervation, and uterine cervix has parasympathetic innervation.
Nerve supply of the external genital organs is provided by the pudendal nerve (n. pudendus).
There are four peritoneal folds. Anteriorly, the vesicouterine fold passes from the level of the uterine isthmus on the bladder. Posteriorly, the rectouterine fold passes from the posterior wall of the uterus to the upper fourth of the vagina, and descents onto the rectum. Laterally, the both broad ligaments passes from the side of the uterus to the lateral wall of the pelvis. Between the two leaves of each broad ligament there is the fallopian tube, the round ligament and the ovarian ligament, in addition to nerves, blood and lymphatics vessels.
Pelvic viscera are surrounded by connective tissue called cellular of pelvic cavity. There is paravesical parametrial, which compose of fatty tissue between broad ligament leaves; paravaginal and pararectal ones. All these cellular spaces are connected between themselves. Infection in these spaces can be spread as cellulitis.
Normal menstrual cycle
Reproduction relies on a complex system of communications between the hypothalamus, pituitary and the ovarian follicular development and ovulation. Sex steroid hormones provides regularity of the phases of the reproductive cycle.
Normal ovulation depends on the complex and interactive hypothalamic — pituitary — ovarian system.
There are responsible changes during the complete reproductive cycle in the target organs: endometrium, breasts, vagina, fallopian tubes. Nervous and endocryne systems undergo cyclic changes too.
In response to the changes, sex steroid hormones are secreted during the ovarian cycle (follicular maturation, ovulation, development of corpus luteum). There are four main stages of the endometrial cycle: desquamation that is menstruation, regeneration, proliferation, and secretion phases. Due to these changes reproductive function can be perfomed: ovulation, fertilization, implantation and emryo development. If implantation doesn't occur functional layer of the endometrium desquamates and the menstrual bleeding begins.
The rythm is genetically determinated and healthy women have it stable during reproductive age. The first day of menstrual bleeding is considered to be the first day of the menstrual cycle.
The modal interval when menstruation occurs is considered to be 27-29 days and may vary from 21 till 35 days.
The duration of menstrual flow is 3-4 days (from 2 till 7 days)
The amount of blood lost is about 50-150 ml per cycle.
The menstruation must be regular, painless.
The reproductive cycle has two phases.
The function of reproductive system is controlled by the complex of brain cortex-hypothalamus, composed of the groups of nerve fibers and cells in which biogenic amines, steroid hormones and gonadotropins perfom reception, translation and transmission of signals from environment and organism. This system has 5 levels and is regulated by feedback mechanisms, while high level structures control the lower level (fig 11,13).
Fig. 11. Regulation of menstrual cycle:
1 — uterus; 2 — fallopian tube; 3 — cervix of uterus; 4 — vagina; 5 — ovary
6, 7, 8 — different stages of ovarian development; 9 — secondary follicle
10 — ovulation; 11 — corpus luteum; 12 — effect of estradiol into uterus
13 — effect of progesterone into uterus
V-level is suprahypothalamic cerebral structures. The menstrual cycle is regulated by brain cortex. Stress or climatic changes can cause abnormalities of ovulation and menstrual cycle. Receiving of information from environment and interreceptions with neurotransmitter structures of central nerves system sends impulses to neurosecretory hypothalamic nuclei.
IVlevel—hypothalamus. Hypothalamic nuclei produce the specific neurohormones, which stimulate pituitary (called as Liberins) and inhibit it (called Statins).
Progesterone ng/ml ~~■"■■ LH mU/ml ' ■
Estradiol 17 pr/ml ——■ FSH lmU/ml —
Follicular phase Ovulation Luteal phase
Fig. 12. Level of hormones in female blood during by menstrual cycle
Hypothalamic ventromedial, arcuate and dorsomedial nuclei produce such hormones as Lul'iberin — releasing hormone that stimulates luteonizing hormone (LH) secretion and Foliberin — releasing hormone that stimulates follicle-stimulating hormone (FSH) secretion by the anterior pituitary.
Gonadotropic liberins mark as GT-RH (gonadotropic releasing hormones) because only they stimulate the pituitary LH and FSH secretion.
The hypothalamus is the pulse generator of the reproductive clock. There is a network of neurons in the anterior and medial parts of the hypothalamus that produces GT-RH. The drops of this neurosecretion have been released from the ends of the brain medial eminentia neurons. GT-RH reaches the anterior pituitary gland through the hypothalamic-pituitary portal plexus. Another goes via veins that flow through dura mater sinuses to the general flow.
Besides GT-RH, there are hypothalamic prolactin-releasing factors and depressing substances which contain dopamine. As hypothalamus responds tosteroid hormones secretion with estradiol production, there is a negative feedback which has been controlled by vertebral arteries. There are estradiol receptors in the arcuate nucleus of hypothalamus. Pulsative infusion of GnRH at 70-90-minutes intervals depends on the level of estradiol hormones.
Ш level—anterior pituitary. Anterior pituitary produces such gonadotropin hormones as follicular-stimulating hormone, luteinizing hormone, prolactin and other tropin hormones such as tireotropic, somatotropic, adrenocorticotropic and lipotropic.
Basophilic cells of the peripheral areas of the anterior pituitary produce FSH. By the chemical structure it is a glycoproteid which has been stimulating the growth and maturation of follicles and follicular fluid secretion.
The basophilic cells of the anterior pituitary central area produce LH. It responds massive estradiol secretion, follicular rupture, ovulation, corpus luteum formation and progesterone production.
Prolactin is a polypeptide. It has opposite function as FSH and LH have had. It responds to breast and target organs growth, maturation and milk secretion.
/7 level — ovaries. An ovary is a target organ for the pituitary hormones. Ovaries respond to pituitary gonadotropin secretion. Ovarian follicles are the basic anatomo-physiologic structure of the ovarian theca.
At birth, human ovary is filled with approximately one million primordial follicles. Each follicle contains an oocyte that is arrested in the prophase stage of meiosis. A single layer of pregranulosa cells surrounds the oocyte, which become the granulosa cells. Premordial follicle is surrounded by basilar membrane that is called hematofollicular barrier. The last one protects oocyte from the uncontrolled influence. The next stage of the development is the transformation of premordial follicle into the primary one. It occurs as a result of excessive reproduction of granulosa cells which contain mucopolysaccharide. The last one forms a special brilliance membrane, which surrounds the oocyte. It is the second protective barrier. As a primary follicle is stimulated, the pretheca cells form two layers — internal (theca interna) which is situated near basilar membrane and secretes hormones and external layer (theca externa). Primary follicle is transformed into antral follicle that contains follicular antrum between the ovum and granulosa cells.
Dominant follicle is the final stage of the follicular maturation. Antral follicles can be transformed into dominant follicles. The follicles undergo ovulation or degeneration.
At the period of puberty only 200 out of 400 000 follicles undergo maturation. Rest of them degenerate.
During the complete reproductive cycle one oocyte is brought to maturity before ovulation. In the process of bringing one oocyte to maturation, a number of oocytes are stimulated to partial maturation but subsequently undergo atresia before reaching ovulation.
An ovarian cycle consists of two phases. The first one —follicular phase, the second — luteal phase. There is an increase of FSH, which stimulates the growth and maturation of follicles in the first phase (fig. 14). It lasts 14 days in 28-days reproductive cycle, 10-11 days in 21-days reproductive cycle, and 17-18 days in 35-days reproductive cycle.
In the beginning of this phase follicle consists of ovum which is surrounded by the thick membrane. It is 2-2,5 mm in diameter. An ovum increases in its sizes and has brilliante membrane in the surface that is called zona pellucida. An ovum is packed with biochemicals that new organism will use until its own genes begin to function. These biochemicals include proteins, RNA, ribosomes, lipids and the molecules that influence cell specialization in the early embryo. An ovum can be an impressive storehouse and it becomes maturate after two-cell divisions in meiosis I, the primary oocyte is divided to form a small polar body and a large haploid secondary oocyte. In meiosis II, reductional secondary oocyte is divided to yield another small polar body and a mature ovum.
Polar bodies are absorbed by the woman's body and normally play no further role in the development. Follicle granulosa membrane forms as a result of follicle cells proliferation. By that time in the central part of these cells the cavity is formed. The last one contains follicular liquid. Granulosa cells those form corona radiata surround an ovum. It is situated in the numerous cells which have been situated near the follicle. This number of cells is called a cumulus oophorus. The follicular fluid contains follicular or estrogenic hormones.
The dominant follicle reaches a diameter of 12-20 mm. As the dominant follicle enlarges and follicular fluid accumulates in it, it grows and rupture. It is the final stage of the follicular phase, which is called ovulation. Ovulation is the process when the membrane of mature follicle is ruptured and oocyte is expelled from the follicle.
Oocyte gets into abdominal cavity and is taken by the uterine tube fimbrias. Process of fertilization takes place in the uterine tubes. After ovulation the dominant follicle transform into the corpus luteum. The second luteal phase of the reproductive cycle begins. There is luteinization — the conversion of granulosa and theca cells to luteal cells with the acquinisation of LH receptors. After this luteal cells can synthesize and secrete large amount of progesterone, that is protein hormone inhibiting FSH secretion.
The corpus luteum has a fixed life term during 14 days, since 15-th to 28-th days of menstrual cycle. There are following processes in corpus luteum: 1) vascularization 2) blossoming 3) involution — in case when pregnancy doesn't occur corpus luteum is called corpus luteum of menstruation. Regression of corpus luteum lasts for 2 months and is over with the formation of white body. If oocyte becomes fertilized and implants within the endometrium, the early pregnancy begins secreting human chorionic gonadotropin (hCG), which sustains the corpus luteum for the following 10-12 weeks. Corpus luteum of pregnancy produces such hormone as relaxin which has tocolytic effect on the uterus.
/ level — target organs (uterus, vagina and breasts).
The endometrial lining of the uterus undergoes dramatic histologic changes during the reproductive cycle. There are cyclic changes in the uterus as well as in the ovaries. They are the most considerable in the functional layer of endometrium and are composed of such phases as desquamation, regeneration, proliferation and secretion.
Desquamation (mensis) lasts from the first to the second or fifth day of the reproductive cycle. During menstruation, the endometrium is sloughed out both with blood.
Functional layer of the endometrium is supplied with blood by spiral arteries. The spiral arteries extend from the arteries of the basal layer. Estrogen is a mitogenic hormone, which stimulates cell growth. With rising estradiol production during the follicular phase of the cycle, there is growth of the spiral arteries those extend into the surface of endometrium only at the end of the proliferative phase. There is an excessive growth of the spiral arteries in the secretory phase. They become most twisty and look like tangles. The capillaries those are situated in the superficial layer of endometrium enlarge in their sizes and look like sinusoids. Spiral arteries of the functional layer contracts before the beginning of menstruation. It causes blood stasis, thrombosis, increasing vessel's permeability and their destroying. The necrosis and sloughing of the tissue occurs. It finishes on the third or fourth day of the menstrual cycle.
At the same time there is an inverse development of corpus luteum in ovaries, progesterone level decreases, hypothalamus produces foliberin and pituitary folitropin which stimulates the maturation of the new follicle in the ovary.
Regeneration phase takes place simultaneously with desquamation and is finally completed up to the 6-7th day of menstrual cycle. The thickness of the endometrium at this moment is 2-5 mm. There is maturing of follicle in the ovary at this time (fig. 17).
Proliferation phase lasts from the 7th to the 14th days of the cycle. The endometrium continues to thicken and the endometrial glands continue to elongate under the estrogens influence. The endometrium thickness is 20 mm, but its glands don't function. Endometrial glands are straight or somewhat twisted. There is a network of argyrophile fibers inside of the endometrial strome. At the final stage of proliferation the endometrial glands become tortuous and spiral arteries reach the surface of endometrium (fig. 15, 18).
There is a completion of the follicle maturation in the ovary, the production of estrogens is peak on the 14th day until the end of proliferative phase. Pituitary stops the FSH-secretion, hypothalamus starts production of luliberin which
Fig. 15. Phase of endometrial proliferation Fig. 16. Phase of endometrial secretion
(electronic microscopy) (electronic microscopy)
stimulates the production of LTH-in pituitary. As a result of this the level of luteonising hormone increases.
Fig. 17. Biopsy of endometrium on Phase of endometrial regeneration
Secretion phase. After ovulation, the corpus luteum produces significant amounts of progesterone, which act on the endometrium to increase the size of endometrial glands and to promote the synthesis and secretion of proteins and other factors (secretory endometrium) in preparation for pregnancy and implantation. This phase lasts from the 14th until the 28th day of cycle (fig. 12).
Fig. 18. Biopsy of endometrium on the 14th day (ovulation). Phase of endometrial proliferation
Fig. 19. Biopsy of endometrium on the 24th day. Phase of endometrial secretion
Glandular epithelium starts to produce the secretion containing glycopro-teids and glycogen. The signs of secretory transformation are revealed on the 15th-18th day. The endometrial glands become tortuous and contain secretory material within the lumina. There is maximum amount of the secretions on the 20th-21th day of cycle. Proteolytic and fibrinolytic activity at this time is the highest.On the 24-27th day of the cycle (late secretion) the endometrium is destroyed and degenerative changes occur in it. Argyrofilic fibers destroy lacunar distension of cappillaries and focal hemorrhages into stroma occur. Endometrium is ready to desintegration and ab-ruptio (fig. 19). Ovarian corpus luteum is well developed by this time. It produces progesterone, which is not a mitogen but causes differentiation of the
tissues containing progesterone receptors. Progesterone converts the proliferate endometrium into a secretory one (fig. 12).
If fertilization and implantation don't occur, progesterone production rapidly diminishes, menstrual corpus luteum is destroyed, functional layer of endometrium is leading to desquamation. Initiating events lead to the beginning of the new cyclic changes in the ovaries and neuroendocrinous system in the wholefemale organism. Some of the foreign authors have described three phases of reproductive cycle:
Uterine cervix is an important biological valve that controles the flow of biological substances into the uterine cavity and from it. Besides, it protects the uterine cavity from the infective agents' penetration. It provides menstrual blood outflow and excretion from the uterine cavity. Endocervix is covered by a simple columnar epithelium which contains secretory crypts. Secretory crypts produce cervical mucus. All uterine cervix structures are very sensitive to the steroid influence. Secretory cells of the endocervix constantly produce sticky transparent liquid, which is called cervical mucus. The quantity and composition of the mucus are regulated by the ovarian hormones secretion and they change during the reproductive cycle. In periovulation period the quantity of the mucus increases up to 600 mg per day, but in luteal phase the mucus quantity is only 50 mg per day.
Hydrated gel is the main component of the mucus that contains hydrocarbo-nates and glycoproteins. Such endocervical mucus characteristics as quantity, water contents and viscosity are maximal at the time of ovulation when the estradiol production is increased. All these changes create the most favourable conditions for fertilization.
Mucus flows down from the internal os to the external one. Epithelial cell microvilli oscillations direct the mucus flow into periphery of the endocervix. It favors the movement of active spermatocytes into the uterine cavity, which are able to overcome cervical mucus flow. Defective spermatocytes move away from the uterine cavity.
Prostaglandines and relaxin also can influence on the uterine cervix. These hormones promote dilation of the cervix in pre-ovulatory period.
Under the. influence of estradiol, the endocervical glands secrete large quantity of thin transparent mucus. Pure watery endocervical mucus contains the increased number of mucin, glycoproteides, salts and decreased quantity of cellular elements. An external os of the cervical canal is more dilated in the ovulation; microfibrils of endocervix are situated parallely. The last one creates the microcanals which promote the migration of spermatocytes. Under the influence of progesterone in post-ovulatory period the cervical canal is closed, the quantity of mucus is decreased, microfibriles are situated as network which is non permeable for spermatocytes. Vaginal cycle
Estradiol stimulates vaginal thickening and maturation of the surface epithelial cells of the vaginal mucous in the follicular phase. Estradiol also facilitates vaginal transudation during the sexual excitement, creating a moist lubricated vagina for sexual intercourse. During the luteal phase of the cycle the vaginal epithelium stops its thickness but the secretory changes are diminished. The thickness of epithelium becomes twice less. In the result of this desquamation occurs. The superficial layer of vaginal epithelium is desquamated in this phase.
Cellular composition of vaginal contents is a biological test of sexual glands' hormonal activity. Superficial, intermediate, parabasal and basal cells ratio depends on the vaginal hormonal state. The quantity of superficial cells are correlated with the estradiol saturation of organism. The more estradiol production results in more superficial cells. During the luteal phase of the cycle the quantity of intermediate cells predominates. Parabasal and basal cells appear during ovarian hypofunction and menopause. They are absent during the normal ovary function in the reproductive women.
The fallopian tubes mucus has parallel folds, which are well developed in the ampulla and become smooth in the isthmus. Folds' height and their direction depend on the ovarian estrogen influence. They are high and parallel in the follicular phase of the cycle that makes sperms' and ovum' migration easier. The fold surface becomes complicated in the luteal phase that blocks the sperm movement.
Under the estrogenic influence the direction of uterine tubes cilia epithelium, fluid composition, contractile activity are changed. The last ones create favorable nditions for fertilization.
The ductal elements in the breasts, nipples and areolae respond to estradiol ;cretion. After ovulation, progesterone stimulates the acinar (milk producing) ds. Because the acinar glands are located in the tissue of breasts, it gives the ~ts a more rounded configuration. Moreover, progesterone makes the venous m on the surface of the breasts and it appears more prominent and accentuates В small Montgomery glands contained within the areolae. These dynamic changes can be observed during the reproductive cycle.
Estrogens are produced by the follicular internal membrane cells and in less quantity by the adrenal cortex. Estradiol, estron and estriol are the main estrogenic hormones. Estradiol is the most active. Estrogenic hormones are circulated in the blood in free state and binding together with proteins. The last one is biological inactive form.
Cholesterol that has been created from lipoproteids is the main structural compound for all the steroid hormones. Steroid hormone secretion is stimulated by FSH and LH and by some enzyme systems, for example aromatases.
The quantity of estrogens predominates in blood plasma. Estrogens enter the liver, then they go into the intestine. Estrogenic hormones are destroyed in the liver and excreted with urine via kidneys. Uterus (endometrium and myometrium), vagina and breasts are target organs for this group of hormones.
The main biological effects of estrogenic hormones:
Thus, in general, estrogenic hormones promote fertilization, interm onse' and normal duration of labor. Menopausal estrogenic deficiency leads to the bone's calcium and phosphorus loss, increases quantity of cholesterol. These factors provoke bones' fractures and cardiac diseases. Estrogenic action inti organism depends on the doses: small or average doses stimulate ovaries, follicul lar development and maturation; large doses depress ovulation; too large dosei lead to atrophic processes in the ovaries.
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