Lecure Notes no. 5: The Menstrual Cycle

 Lecture 5: Menstruation

 

 

Normal Menstrual cycle

The normal human menstrual cycle can be divided into two segments: the ovarian cycle and the uterine cycle, based on the organ under examination.

 

The ovarian cycle may be further divided into follicular and luteal phases, whereas the uterine cycle is
divided into corresponding proliferative and secretory phases

 

1. Follicular phase—hormonal feedback promotes the orderly development of a single dominant follicle, which should be mature at midcycle and prepared for ovulation. The average length of the human follicular phase ranges from 10 to 14 days, and variability in this length is responsible for most variations in total cycle length.

2. Luteal phase—the time from ovulation to the onset of menses has an average length of 14 days.

 

A normal menstrual cycle lasts from 21 to 35 days, with 2 to 6 days of flow and an average blood loss of 20 to 60 mL. However, studies of large numbers of women with normal menstrual cycles have shown that only approximately two-thirds of adult women have cycles lasting 21 to 35 days.

 

The extremes of reproductive life (after menarche and perimenopause) are characterized by a higher percentage of anovulatory or irregularly timed cycles.

 

Hormonal Variations The relative pattern of ovarian, uterine, and hormonal variation along the normal menstrual cycle is shown in 5.1

1. At the beginning of each monthly menstrual cycle, levels of gonadal steroids are low and have been decreasing since the end of the luteal phase of the previous cycle.

2. With the demise of the corpus luteum, FSH levels begin to rise, and a cohort of growing follicles is recruited. These follicles each secrete increasing levels of estrogen as they grow in the follicular phase. The increase in estrogen, in turn, is the stimulus for uterine endometrial proliferation.

3. Rising estrogen levels provide negative feedback on pituitary FSH secretion, which begins to wane by the midpoint of the follicular phase. In addition, the growing follicles produce inhibin-B, which also suppresses FSH secretion by the
pituitary. Conversely, LH initially decreases in response to rising estradiol levels, but late in the follicular phase, the LH level is increased dramatically (biphasic response).

4. At the end of the follicular phase (just before ovulation), FSH-induced LH receptors are present on granulosa cells and, with LH stimulation, modulate the secretion of progesterone.

5. After a sufficient degree of estrogenic stimulation, the pituitary LH surge is triggered, which is the proximate cause of ovulation that occurs 24 to 36 hours later. Ovulation heralds the transition to the luteal–secretory phase.

6. The estrogen level decreases through the early luteal phase from just before ovulation until the mid-luteal phase when it begins to rise again as a result of corpus luteum secretion. Similarly, inhibin-A is secreted by the corpus luteum.

7. Progesterone levels rise precipitously after ovulation and can be used as a presumptive sign that ovulation has occurred.

8. Progesterone, estrogen, and inhibin-A act centrally to suppress gonadotropin secretion and new follicular growth. These hormones remain elevated through the lifespan of the corpus luteum and then wane with its demise, thereby setting the stage for the next cycle.

 

Uterus
Cyclic Changes of the Endometrium

 This cycling portion of the endometrium is known as the decidua functionalis and is composed of a deeply situated intermediate zone (stratum spongiosum) and a superficial compact zone (stratum compactum).

 

The decidua basalis is the deepest region of the endometrium. It does not undergo significant monthly proliferation but, instead, is the source of endometrial regeneration after each menses.

 

In the typical 28-day cycle, ovulation occurs on cycle day 14. Within 48 to 72 hours following ovulation, the onset of progesterone secretion produces a shift in the histologic appearance of the endometrium to the secretory phase, so named for the clear presence of eosinophilic protein-rich secretory products in the glandular lumen.

In contrast to the proliferative phase, the secretory phase of the menstrual cycle is characterized by the cellular effects of progesterone in addition to estrogen.  

 

 

 

During the secretory phase, the endometrial glands form characteristic periodic acid–Schiff positive–staining, glycogen-containing vacuoles.  

 

Menses
In the absence of implantation, glandular secretion ceases, and an irregular breakdown of the decidua functionalis occurs. The resultant shedding of this layer of the endometrium is termed menses. The destruction of the corpus luteum and its production of estrogen and progesterone is the presumed cause of the shedding.

 

Ovarian Follicular Development The number of oocytes peaks in the fetus at 6 to 7 million by 20 weeks of gestation. Simultaneously (and peaking at the fifth month of gestation), atresia of the oogonia occurs, rapidly followed by follicular atresia. At birth, only 1 to 2 million oocytes remain in the ovaries, and at puberty, only 300,000 of the original 6 to 7 million oocytes are available for ovulation. Of these, only 400 to 500 will ultimately be released during ovulation. By the time of menopause, the ovary will be composed primarily of dense stromal tissue with only rare interspersed oocytes remaining.

 

 

Preovulatory Follicle

Preovulatory follicles are characterized by a fluid-filled antrum that is composed of plasma with granulosa-cell secretions.

 

The granulosa cells at this point have further differentiated into a heterogeneous population. The oocyte remains connected to the follicle by a stalk of specialized granulosa known as the cumulus oophorus.

Rising estrogen levels have a negative feedback effect on FSH secretion. Conversely, LH undergoes biphasic regulation by circulating estrogens. At lower concentrations, estrogens inhibit LH secretion. At higher levels, however, estrogen enhances LH release.

 

This stimulation requires a sustained high level of estrogen (200 pg/mL) for more than 48 hours (78). Once the rising estrogen level produces positive feedback, a substantial surge in LH secretion occurs. Concomitant to these events, the local estrogen-FSH interactions in the dominant follicle induce LH receptors on the granulosa cells. Thus, exposure to high levels of LH results in a specific response by the dominant follicle—the result is luteinization of the granulosa cells, production of progesterone, and initiation of ovulation. In general, ovulation will occur in the single mature, or Graafian, follicle 10 to 12 hours after the LH peak or 34 to 36 hours after the initial rise in midcycle LH

 

Ovulation
The midcycle LH surge is responsible for a dramatic increase in local concentrations of prostaglandins and proteolytic enzymes in the follicular wall

 

Luteal Phase

Structure of Corpus Luteum After ovulation, the remaining follicular shell is transformed into the primary regulator of the luteal phase: the corpus luteum.

 

Hormonal Function and Regulation The hormonal changes of the luteal phase are characterized by a series of negative feedback interactions designed to lead to regression of the corpus luteum if pregnancy does not occur. Corpus luteum steroids (estradiol and progesterone) provide negative central feedback and cause a decrease in FSH and LH secretion. Continued secretion of both steroids will decrease the stimuli for subsequent follicular recruitment. Similarly, luteal secretion of inhibin also potentiates FSH withdrawal. In the ovary, local production of progesterone inhibits the further development and recruitment of additional follicles.

Continued corpus luteum function depends on continued LH production. In the absence of this stimulation, the corpus luteum will invariably regress after 12 to 16 days and form the scarlike corpora Albicans

 

Summary of Menstrual Cycle Regulation 

 

Following is a summary of the regulation of the menstrual cycle:

1. GnRH is produced in the arcuate nucleus of the hypothalamus and secreted in a pulsatile fashion into the portal circulation, where it travels to the anterior pituitary

2. Ovarian follicular development moves from a period of gonadotropin independence to a phase of FSH dependence.

3. As the corpus luteum of the previous cycle fades, luteal production of progesterone and inhibin A decreases, allowing FSH levels to rise.

4. In response to FSH stimulus, the follicles grow and differentiate, and secrete increasing amounts of estrogen and inhibin-B.

5. Estrogen stimulates growth and differentiation of the functional layer of the endometrium, which prepares for implantation. Estrogens work with FSH in stimulating follicular development.

6. The two-cell two-gonadotropin theory dictates that with LH stimulation, the ovarian theca cells will produce androgens that are converted by the granulosa cells into estrogens under the stimulus of FSH.

7. Rising estrogen and inhibin levels negatively feedback the pituitary gland and hypothalamus and decrease the secretion of FSH.

8. The one follicle destined to ovulate each cycle is called the dominant follicle. It has relatively more FSH receptors and produces a larger concentration of estrogens than the follicles that will undergo atresia. It can continue to grow despite falling FSH levels.

9. Sustained high estrogen levels cause a surge in pituitary LH secretion that triggers ovulation, progesterone production, and the shift to the secretory, or luteal, phase.

10. Luteal function is dependent on the presence of LH. However, the corpus luteum secretes estrogen, progesterone, and inhibin-A, which serve to maintain gonadotropin suppression. Without continued LH secretion, the corpus luteum will regress after 12 to 16 days. The resulting loss of progesterone secretion results in menstruation.

11. If pregnancy occurs, the embryo secretes hCG, which mimics the action of LH by sustaining the corpus luteum. The corpus luteum continues to secrete progesterone and supports the secretory endometrium, allowing the pregnancy to continue to develop.

 

The decidua is classified into three parts based on anatomical location.

 

1. Decidua directly beneath blastocyst implantation is modified by trophoblast invasion and becomes the decidua basalis.

2. The decidua capsularis overlies the enlarging blastocyst and initially separates it from the rest of the uterine cavity.

This portion is most prominent during the second month of pregnancy, consisting of decidual cells covered by a single layer of flattened epithelial cells. Internally, it contacts the avascular, extraembryonic fetal membrane—the chorion laeve.

3. The remainder of the uterus is lined by decidua parietalis—sometimes called decidua vera when decidua capsularis and parietalis are joined.

 

  

LECTURE NOTES NO. 4 Internal Generative Anatomy

Lecture 4: Internal Generative Anatomy

 

 

A. Ovary – are almond-shaped and -sized female gonads in which the oocytes (female gametes or germ cells) develop. They are also endocrine glands that produce reproductive hormones.

1. In nulliparas (women who have not borne children) are paired, almond-shaped, pinkish-white structures measuring about 2.5 to 5 cm in length, 1.5 to 3 cm in width, and 0.6 to 1.5 cm in thickness.

2. the ovaries are situated in the upper part of the pelvic cavity and rest in a slight depression on the lateral wall of the pelvis between the divergent external and internal iliac vessels—the ovarian fossa of Waldeyer

 

3. The ovary has 2 ends:

a. Upper (Tubal) End / Superior Pole:  is directed up & laterally & attached to:

i. Ovarian fimbria of the Fallopian tube.

ii. Suspensory (infundibulo-pelvic) ligament of the ovary

iii. It extends from the upper or tubal pole to the pelvic wall which carries the ovarian vessels and nerves

b. Lower (Uterine) End / Inferior pole: is directed down & medially. It is attached to the upper lateral angle of the uterus by the ligament of the ovary.

 

4. Ligaments of The Ovary

a. infundibulopelvic or suspensory ligament of the ovary:

i. It extends laterally from the tubal end of the ovary to the sidewall of the pelvis.

ii. It is a peritoneal fold that transmits the ovarian vessels, nerves & lymphatics to the broad ligament.

b. Mesovarium:

i. It is the peritoneal fold that extends from the upper layer of the broad ligament to the anterior border of the ovary.

ii. It transmits the ovarian vessels & nerves to the ovary.

c. Ovarian Ligament:

i. A fibromuscular cord or ligament is a remnant of the gubernaculum, the embryonic fibrous cord that attaches the developing gonad to the floor of the pelvis.

ii. Extends from the lateral and posterior portion of the uterus, just beneath the tubal insertion, to the uterine pole of the ovary

 

5. Blood Supply

a. Arteries à The ovarian artery arises from the abdominal aorta at the level of the first lumbar vertebra.

b. Veins à The ovarian vein drains into the inferior vena cava on the right side and into the left renal vein on the left side.

6. Lymphatic Lymph Drainage à The lymph vessels of the ovary follow the ovarian artery and drain into the para-aortic nodes

7. Nerve Supply

a. Parasympathetic: From pelvic splanchnic nerves (S2, S3, S4).

b.  Sympathetic: from T10, T11.

 

8. The ovary is suspended in the peritoneal cavity and its surface is not covered by the peritoneum; The oocyte expelled at ovulation passes into the peritoneal cavity. However, its intraperitoneal life is short because it is normally trapped by the fimbriae of the infundibulum of the uterine tube and carried into the ampulla, where it may be fertilized.

 

9. Ovarian Histology:

a. Ovary reveals two distinct regions:

i. Cortex (OUTER LAYER)

Þ The functional layer is the site of ovum formation & maturation.

Þ It contains the primordial follicles and Graafian follicles, corpus luteum and corpus Albicans  

Þ The outermost portion of the cortex, which is dull and whitish, is designated as the tunica albuginea;

Þ on its surface, there is a single layer of cuboidal epithelium, the germinal epithelium of Waldeyer.

 

ii. MEDULLA – (CENTRAL PORTION) Layer which contains the blood vessels, lymphatics, nerves & muscle fibers.

Þ Composed loose connective tissue that is continuous with that of the mesovarium.

Þ There are a large number of arteries and vein large contorted blood vessels, lymphatic vessels, and nerves

Þ Small number of smooth muscle fibers that are continuous with those in the suspensory ligament

 

 

10. Two interrelated functions of the ovary:

a. Exocrine function: produce, maturation, and discharge of  ova  

i. gametogenesis (the production of gametes)

Þ the production of female gametes is called oogenesis.

Þ Developing gametes are called oocytes.

Þ mature gametes are called ova.

ii. Organ for ovulation = OVULATION IS THE CARDINAL FUNCTION OF THE OVARY

b. Endocrine function: secrete estrogen & progesterone hormones steroidogenesis (the production of steroids).

i. Two major groups of steroid hormones—estrogens and progestogens — are secreted by the ovaries.

Þ Estrogens

· promote the growth and maturation of internal and external sex organs and are responsible for the female sex characteristics that develop at puberty.

· act on mammary glands to promote breast development by stimulating ductal and stromal growth and accumulation of adipose tissue.

Þ Progestogens

· prepare the internal sex organs, mainly the uterus, for pregnancy by promoting secretory changes in the endometrium (discussed in the section on cyclic changes in the endometrium).

· prepare the mammary gland for lactation by promoting lobular proliferation.

ii. Both hormones play an important role in the menstrual cycle by preparing the uterus for the implantation of a fertilized ovum.

iii. If implantation does not occur, the endometrium of the uterus degenerates and menstruation follows.

 

 

11. Growth and Development of the ovary:

a. In prepubertal females, the connective tissue capsule (tunica albuginea of the ovary) comprising the surface of the ovary is covered by a smooth layer of ovarian mesothelium or surface (germinal) epithelium, a single layer of cuboidal cells that gives the surface a dull, grayish appearance, contrasting with the shiny surface of the adjacent peritoneal mesovarium with which it is smooth and continuous

b. During reproductive life, it becomes progressively scarred, irregular, and distorted because of the repeated rupture of ovarian follicles and discharge of oocytes during ovulation. The ovarian scarring is less in women who have been taking oral contraceptives that inhibit ovulation.

i. Young women = the exterior surface smooth, dull-white surface through which glisten several small, clear follicles

ii. As the woman ages = more corrugated

iii. elderly = convoluted markedly.

iv. In postmenopausal women, the ovaries are about one-fourth the size observed during the reproductive period.

c. Germ Cell Maturation of the ovaries:

i. Two (2) Months Intrauterine = 600,000 Oogonia

ii. Five (5) Months Intrauterine = 6,800,000

iii. At Birth = 2 Million Oocytes

iv. Pre-Puberty / Childhood = 200,000 To 400,000 (439,000 Oocytes In Girls Under 15)

v. 36 Years Old = 30,000 To 40,000

vi. Active Cyclical Ovulation In The Entire Reproductive Life = 400-500

vii. Menopause = absent ovum

 

 

B. FALLOPIAN TUBE

1. Two slender muscular tubes arise from each of the upper corners of the uterine body and extend outward. Provides a place for fertilization (conception, fecundation, and impregnation) of ova by the sperm.

2. The uterine tubes (formerly called oviducts or fallopian tubes) is lined by a single layer of columnar cells, some of them ciliated and others secretory

3. The musculature of the fallopian tube is arranged in an inner circular and an outer longitudinal layer.

4. The uterine tubes (approximately 8 to 14 cm in length and are covered by peritoneum) lie in a narrow mesentery, the mesosalpinx, forming the free anterosuperior edges of the broad ligaments.

 

5. Function:

a. passageway of the ovum from ovaries à conduct the oocyte, discharged monthly from an ovary during child-bearing years, from the periovarian peritoneal cavity to the uterine cavity

b. passageway of sperm from uterus

c. site of fertilization.

i. Note:

Þ 5 minutes-sperm as quickly as this reach site of fertilization from time of ejaculation

Þ 12-24h average-mature ovum is capable of being fertilized after ovulation

 

6. The uterine tubes are divisible into four parts, from lateral to medial:

a. Infundibulum:

i.  the funnel-shaped distal end of the tube that opens into the peritoneal cavity through the abdominal ostium.

ii. The finger-like processes of the fimbriated end of the infundibulum (fimbriae) spread over the medial surface of the ovary; one large ovarian fimbria is attached to the superior pole of the ovary.

b. Ampulla:

i. the widest (measures from 5 to 8 mm) and longest part of the tube, which begins at the medial end of the infundibulum;

ii. The oviduct is surrounded completely by the peritoneum except at the attachment of the mesosalpinx.

iii. fertilization of the oocyte usually occurs in the ampulla.

c. Isthmus 

i. the narrowest portion of the tube measures from 2 to 3 mm in diameter

ii. the thick-walled part of the tube which enters the uterine horn.

d. Uterine part/intramural/interstitial à the short intramural segment of the tube that passes through the muscular wall of the uterus in an obliquely upward and outward and opens via the uterine ostium into the uterine cavity at the uterine horn.

 

7. The tubal musculature undergoes rhythmic contractions constantly, the rate of which varies with the hormonal changes of the ovarian cycle. The greatest frequency and intensity of contractions are reached during the transport of ova. Contractions are slowest and weakest during pregnancy

 

 A. UTERUS

 is pyriform or hollow pear-shaped muscular organ

1. Location: It is in the central part of the pelvis:

a. Anterior: Bladder à ureterovesical pouch

b. Postero-superior: Rectum à the rectouterine pouch recto-uterine cul-de-sac, or pouch of Douglas with coils of ileum or sigmoid colon.

c. Laterally: broad ligament and the uterine artery and vein. The supravaginal cervix is related to the ureter.

2. Measurements

a. Dimension:

i. Non-Pregnant = 3 inches long, 2 inches wide, 1 inch thick

ii. Pregnant = 32 cms, 24 cms., 20-24 cms

b. Weight:

i. Non-Pregnant = 50-70 gms

ii. Pregnant = 1100 g at term

c. LENGTH

i. prepubertal: 2.5 to 3.5 cm

ii. Adult nulliparous: 6 to 8 cm  

iii. Multiparous:  9 to 10 cm  

d. Capacity:    

i. 20ml – 75 ml cavity {ave. of 30 ml}

ii. Its total volume averages about 5 L at term

iii. can hold at a maximum of 20 L

3. Size and Shape of the uterus

a. Non-Pregnant original shape – Flattened pear in shape

b. Pregnant shape: Globular (1^st tri) and Ovoid (2^nd- 3^rd Tri)  

4. Functions of Uterus:

a. Organ of pregnancy/implantation (nidation) and menstruation

b. Receives the ova from the fallopian tube

c. Furnishes protection for a growing fetus

d. Labor power-powerful contractile smooth muscle

5. Two major but unequal parts:

a. upper triangular portion= the body/corpus

b. Lower, cylindrical, or a fusiform portion, = cervix, which projects into the vagina.

 

6. POSITIONS OF THE UTERUS

a. Normal Position:

i. ANTEVERTED - the long axis of the uterus is bent forward on the long axis of the vagina. This position is referred to as anteversion (90 degrees) of the uterus.

ii. ANTEFLEXED - The long axis of the body of the uterus is bent forward at the level of the internal os with the long axis of the cervix.

Þ This position is termed anteflexion (170 degrees) of the uterus.

b. Abnormal position: retroverted, retroflexed

i. RETROVERTED - the fundus and body of the uterus are bent backward on the vagina so that they lie in the rectouterine pouch (pouch of Douglas).

ii. RETROFLEXED - the body of the uterus bent backward on the cervix

 

What is the normal position of a pregnant uterus?

— A.  anteversion c.  Retroversion

— B.  Anteflexion d.  Retroflection

 

7. Parts of the Uterus: fundus, body, isthmus, and cervix

a. Fundus & CORNUA

i. The convex upper segment/ dome-shaped part between the points of insertion/opening of the fallopian tubes is called the fundus

ii. Emerges from the CORNUA of the uterus at the junction of the superior and lateral margins

iii. Fundus = Most vascular portion; Normal implantation site (2/3 Upper posterior; 1/3 Upper Anterior); Strongest Site of Contraction

iv. Uppermost convex portion of the fundus:

Þ Palpated to determine uterine growth during pregnancy

Þ To assess uterine contractions during labor

Þ To determine Involution during the postpartum period

 

b. Body/Corpus:

i. It is the part extending from the level of opening of the Fallopian tubes to the constriction called the isthmus.

ii. It contains the uterine cavity. It is the site of implantation of the zygote & also the site of menstruation.

iii. Uterine wall is composed of serosal, muscular, and mucosal layers. 

 

 

Þ PERIMETRIUM: SEROSAL LAYER

· is formed by the peritoneum that covers the uterus.

· firmly adherent except at sites just above the bladder and at the lateral margins = form the broad ligaments

Þ MYOMETRIUM: MUSCULAR LAYER

· The myometrium makes up the major portion of the uterus composed of bundles of smooth muscle united by connective tissue in which there are many elastic fibers.

· According to Schwalm and Dubrauszky (1966), the number of muscle fibers of the uterus progressively diminishes caudally such that, in the cervix, muscle comprises only 10 percent of the tissue mass.

· During pregnancy, the upper myometrium undergoes marked hypertrophy, but there is no significant change in cervical muscle content.

Þ ENDOMETRIUM: MUCOSAL LAYER

· lines the uterine cavity in nonpregnant women.  It becomes DECIDUA during pregnancy

· The endometrium or decidua is the anatomical site of blastocyst apposition, implantation, and placental development

· After menopause, the endometrium is atrophic and the epithelium flattens.  

· The endometrium can be subdivided into two zones:

(1) The basal layer adjacent to the myometrium, contains highly cellular lamina propria and the deep basal ends of the uterine glands.

(2) The superficial functional layer (or functionalis) contains more spongy and less cellular lamina propria, richer in ground substance, most of the length of the glands, as well as the surface epithelium

(a) The functional layer undergoes profound changes during the menstrual cycles, but the basal layer remains relatively unchanged

 

 

 

Prostaglandins

· Produced by the endometrium

· Technically, not a hormone because they are produced by tissues rather than special glands

· Play a role in rupturing the Graafian follicle

· Large amount of prostaglandins are found in the menstrual blood

· Found to have a contracting effect on the uterus

 

c. Isthmus:

i. The isthmus is that portion of the uterus between the internal cervical os and the endometrial.

ii. special obstetrical significance: it forms the lower uterine segment during pregnancy

iii. Isthmus – a common site for uterine rupture because it is designed to be thin & passive

Þ Causes:

· Faulty Fundal Push

· Unwise Use Of Oxytocin

· Previous C-section In Labor

· Overdistention 2˚:

(1) Polyhydramnios

(2) LGA

(3) Multifetal pregnancy

iv. The isthmus= between the internal cervical os and the endometrial cavity.

v. Special obstetrical significance:

Þ isthmus forms the lower uterine segment during pregnancy.

Þ The oviducts, or fallopian tubes, emerge from the cornua of the uterus at the junction of the superior and lateral margins.

Þ The round ligaments insert below the tubes on the anterior side. They are covered by a fold of the peritoneum that extends to the pelvic sidewall. These folds are called the broad ligaments; however, they do not constitute the anatomical definition of a ligament.

 

d. Cervix

i. External cervical os = distal opening to the vagina

ii. Cervical canal = the cavity

iii. Internal cervical os = opening to the uterus

iv. UTERINE CERVIX RATIO AS TO LENGTH

Þ Premenarchal girl:  the body of the uterus is only half as long as the cervix.

Þ Nulliparous women: equal in length.

Þ Multiparous women:  the cervix - a little more than a third of the total length of the organ.

Þ After menopause, uterine size decreases as a consequence of atrophy of both myometrium and endometrium. 

v. LOWER VAGINAL PORTION OF THE CERVIX also called the portion vaginalis.

Þ Nulliparous: external cervical os is a small, regular, oval opening.

Þ After childbirth, the orifice:  transverse slit that is divided such that there are the so-called anterior and posterior lips of the cervix.

Þ If torn deeply during delivery, it might heal in such a manner that it appears to be irregular, nodular, or stellate

 

 

D. VAGINA

8. Anatomy

a. is interposed anteriorly and posteriorly between the bladder and the rectum

b. the length of the vaginal sidewalls and give the vagina an H shape when viewed in cross-section

c. numerous thin transverse ridges, known as rugae, are found along the length of the anterior and posterior vaginal walls.

9. Functions:

a. Excretory canal of the uterus

b. Passageway of menstrual flow and uterine secretions

c. Passageway of the fetus

d. Organ of copulation

e. Semen depository

10. Embryonic Origin

a. Upper portion:  arises from the Mullerian ducts

b. Lower portion:  formed from the urogenital sinus.

11. BOARDERS

a. Anteriorly: bladder and urethra are separated by connective tissue called = vesicovaginal septum. 

b. Posteriorly:  lower portion of the vagina and the rectum is separated connective tissues called = rectovaginal septum. 

c. Upper fourth of the vagina is separated from the rectum by the rectouterine pouch, also called the cul-de-sac of Douglas. 

12. Vagina Length

a. ANTERIOR VAGINAL WALL: 6 to 8 cm

b. POSTERIOR VAGINAL WALL: 7 to 10 cm

c. the average woman may have a shortening of her vagina by 0.8 cm

13. Vaginal Fornix

a. Upper end of the vaginal vault is subdivided into anterior, posterior, and two lateral fornices by the uterine cervix.

b. Clinical importance: internal pelvic organs palpated through their thin walls; posterior fornix provides surgical access to the peritoneal cavity

i. ANTERIOR FORNIX EROGENOUS ZONE (aka AFE zone, AFE, A-spot, epicenter, deep spot, or second G-spot)

14. Vaginal Rugae = thin transverse ridges found along the length of the anterior and posterior vaginal walls.

a. Nulliparous women:  numerous transverse ridges, or rugae - right angles to the longitudinal ridges.

b. before menarche = Not present

c. Postmenopausal & multiparous women: the vaginal walls are smooth.

15. Vaginal Layer

a. Composed of nonkeratinized/noncornified stratified squamous epithelium and underlying lamina propria

b. Beneath the epithelium is a thin fibromuscular coat:

i. Inner layer = muscular layer- a circular pattern of smooth muscle, collagen, elastin.

ii. Outer layer = adventitial layer- a longitudinal pattern of smooth muscle, collagen, elastin.

c. A thin layer of connective tissue beneath the mucosa and the muscularis is rich in blood vessels. (controversial whether this connective tissue—often referred to as perivaginal endopelvic fascia—is a definite fascial plane in the strict anatomical sense)

 

16. Other information about the vagina:

a. There are NO vaginal glands.

b. VAGINAL INCLUSION CYSTS = NOT TRUE GLANDS.

i. it is kept moist by a small amount of secretion from the CERVIX 

ii. lubricated by a transudate that originates from the vaginal subepithelial capillary plexus layer and crosses the permeable epithelial layer

c. Normal vaginal fluid is white and generally not malodorous

i. Examination of cells that are exfoliated from the vaginal epithelium, can identify the various hormonal events of the ovarian cycle

Þ Lactic acid is the predominant acid in the vagina and responsible for the vaginal pH in most healthy women to be < 4.5. The majority of the lactic acid comes from the anaerobic glycolysis of glycogen degradation products by Lactobacilli, as well as by another lactic acid-producing bacteria. The vaginal epithelial cells also release a relatively minor amount of lactic acid into the vaginal lumen. L. crispatus, L. gasseri, and L. jensenii each produce both the D and L isomeric forms of lactic acid. 

Þ During pregnancy= copious, acidic vaginal secretion, which normally consists of curds like the product of exfoliated epithelium and bacteria-lactobacillus species 

· (Lactobacillus crispatus  and Lactobacillus jensenii. ) = recovered in higher concentrations during pregnancy than in nonpregnant women  

(1) Normal Vaginal pH:

(a) 7.0 = premenarchial

(b) 3.8 to 4.5 = reproductive age

(c) 6.5 – 7.0 = menopause

Þ Fungi and Bacteria are present in the vagina such as = Candida and streptococcus

Þ Remember: The pH of vaginal secretions normally ranges from 3.8 to 4.5

Þ, whereas that of amnionic fluid is usually 7.0 to 7.5

 

d. Vaginal Arterial Blood Supply

i. The proximal portion=the cervical branch of the uterine artery and by the vaginal artery (arise from the uterine, inferior vesical, or directly from the internal iliac artery)

ii. Posterior Vaginal wall = The middle rectal artery

iii. distal walls = receive contributions from the internal pudendal artery.

 

17. In what situation will the Vaginal pH change?

a. INCREASED VAGINAL pH CAUSES (pH >4.5):

i. NON-INFECTIOUS CAUSES:

Þ Menses

Þ Cervical Mucus increased (e.g. Ovulation)

Þ Semen in vagina following intercourse

Þ Rupture of Membranes in pregnancy

Þ Estrogen deficiency (Hypoestrogenism)

ii. INFECTIOUS CAUSES

Þ Trichomoniasis

Þ Bacterial Vaginosis

Þ Infection associated with Retained Foreign Body

b. RARE INFECTIOUS CAUSES

i. Group A Streptococcal Vaginitis

ii. Inflammatory Vaginitis with Desquamation

 

18. VAGINITIS à inflammation of the vagina characterized by an increased vaginal discharge containing numerous WBCs

a. Causes:

i. Douches

ii. Antibiotics

iii. Hormones

iv. Contraceptives (oral and topical)

v. Change in a sexual partner

b. What are the most common forms of vaginitis? What are their symptoms?

i. Candida vaginitis is caused by an overgrowth of one of many Candida species.

ii. Bacterial vaginosis is caused by an imbalance in the normal flora.

iii. Trichomoniasis is due to infection with a parasite, Trichomonas vaginalis. It is a sexually transmitted disease (STD).

iv. Atrophic vaginitis is irritation and inflammation secondary to atrophy of the vaginal tissue.

c. All these conditions can present with one or more of the following symptoms:

i. Increased vaginal discharge

ii. Malodorous discharge

iii. Vaginal or vulvar pruritus

iv. Dyspareunia

v. Vaginal or vulvar burning

vi. Vulvar edema

vii. Erythema.

d. The characteristics of the symptoms and the gross description of the discharge are NOT enough to establish the diagnosis

e. How are the common causes of vaginitis distinguished from one another?

	Normal	Candidiasis	Bacterial Vaginosis	Trichomoniasis
Gross appearance	White, thin	White, thick	Thin, grey-white	Thick, milky; grey-white, or green
pH	4.0	<3.5	> 5.5	> 5.5
Microscopic	Epithelial cells only	Budding hyphae on KOH prep	Clue cells; few WBCs	Motile trichomonads
"Whiff" test	-	-	+	-