Composition And Properties Of Menses

Menses principally consists of blood, desquamated endometrial tissue, sloughed vaginal epithelial cells, cervico-vaginal secretions, and endogenous vaginal microbes. Consequently, menses differs from venous blood both in its composition (Table 1) and in its physical properties. The composition and physical properties of menses vary among individuals and over the course of menstrual flow. Hence, mean values for menses reported in the accompanying table represent values obtained from sample populations and may not broadly reflect population norms.

Menses may be considered a suspension of blood- and tissue-derived solids within a mixture of serum and cervico-vaginal fluid. Agglomerates of tissue debris, red blood cells, and mucins are scattered throughout a serum-like phase. Figure 2 shows microscopic images obtained from two locations within the same sample of menses. The images show intact and ruptured red blood cells, finer particulate matter, as well as predominantly fluid regions, demonstrating the nonhomogenous nature of menses (6).

The blood content of menses depends on the extent of endometrial breakdown and dilution of blood- and tissue-derived constituents with cervico-vaginal fluid. Vaginal fluid in menses contributes principally water, common electrolytes,

Table 1 Composition of Venous Blood and Mensesa

Venous blood

Table 1 Composition of Venous Blood and Mensesa

Venous blood

Component

Mean

Range0

Hematological components

Red blood cells

N/A

4.8 ± 2.0 x 106

(cells per mm3)

White blood cells

N/A

2.4-2.8 x 106

(cells per mm3)

Platelets

N/A

1.4-3.5 x 10s

(cells per mm3)

Hemoglobin

14

12-18

(g/dL)

Albumin (g/L)

44 ± 8.8

N/A

Hematological components (coagulation factors)

Prothrombin

Present in 24/24

N/A

subjects studied

Plasminogen activator

0.15

0-0.2d

(CTA units/mL)

Plasmin(ogen) protein

0.15 ± 0.03

N/A

(g/L)

Plasmin activity

0

0

(|xmol/L)

a2-antiplasmin activity

Present in 24/24

N/A

subjects studied

Fibrinogen (mg/100 mL)

N/A

Mean Range Reference13

Not detected Not detected (12)

Not detected N/A (11)

Not detected Not detected (14)

Fibrinogen degradation

10.5 ± 0.8

N/A

>1280

N/A

(14)

products (|xg/mL)

Inorganic materials

Sodium (ppm)

3300

N/A

2600

2300-3100

(33)

Calcium (ppm)

105

85-105

100

90-110

(33)

Iron (ppm)e

455

390-585f

320

60-650

(10)

Phosphate (ppm)

270

N/A

360

320-450

(33)

Chloride (ppm)

3600

N/A

3500

3200-3900

(33)

Organic materials

Serum protein

7

6.0-8.0

6.5

5.9-7.5

(33)

(g/lOOmL)

Amino acids (ppm)

100

N/A

250

160-350

(33)

Nitrogen (ppm)

350

N/A

800

600-1000

(33)

Urea (ppm)

400

N/A

150

100-200

(33)

Bilirubin (ppm)

7

2-9

4

3-7

(33)

Fatty acids (ppm)

3500

N/A

3000

2200-3300

(33)

Total cholesterol (ppm)

1750

1400-3100®

1500

1350-1700

(33)

Blood sugar (ppm)

900

700-110011

500

300-500

(33)

Glycogen (ppm)

350

N/A

500

400-600

(33)

Lactic acid (ppm)

110

60-160

300

240-370

(33)

aCited values for menses are based on sample populations and do not necessarily represent population norms. N/A: not available. References for menses values only.

cNormal clinical ranges according to (34), unless otherwise referenced. dFrom Ref. 11.

^Calculated from hemoglobin content. fFrom Ref. 9.

EFor ages 30 to 49, as observed clinically (34). Values skew higher with age. Fasting glucose.

Abbreviation: ppm, parts per million (or |j,g/mL).

aCited values for menses are based on sample populations and do not necessarily represent population norms. N/A: not available. References for menses values only.

cNormal clinical ranges according to (34), unless otherwise referenced. dFrom Ref. 11.

^Calculated from hemoglobin content. fFrom Ref. 9.

EFor ages 30 to 49, as observed clinically (34). Values skew higher with age. Fasting glucose.

Abbreviation: ppm, parts per million (or |j,g/mL).

Figure 2 Images of menses obtained by differential interference contrast microscopy (approximately 1000 x magnification), demonstrating cellular agglomerates and a predominantly fluid phase within the same menses sample.

organic moieties, and at least 14 proteins (7), including glycoproteins with molecular weights up to 82 kDa (8).

Consequently, the concentrations of many elements in menses are lower than in venous blood. For example, solid matter in venous blood after evaporation of water is typically 20% of the mass, but the solid matter in menses ranges from 7% to 23% of the total mass; hence, menstrual fluid often has a higher water content than venous blood (9). Likewise, the hemoglobin and iron content of menses depend on the extent of endometrial breakdown and display a far broader range than that of venous blood (Table 1). The blood content of menses averaged over all days of menstrual flow is close to 50% (5). The average hemoglobin content of venous blood is about 14 g/dL, but the hemoglobin content of menses samples obtained at the time of peak flow was closer to 10 g/L, with a range of 1.5 g/dL to 19.9 g/dL (10). White blood cell and platelet counts in menses are as much as 100-fold lower than those of venous blood (Table 1).

The pH of menses is similar to that of venous blood, reflecting the serum content of its fluid phase. The median pH measured in a range of menses samples was 7.2 with a skewed distribution tailing into the range of pH 5 to 6 (measured at 25°C using a small diameter glass electrode) (9).

The concentrations of certain serum-derived constituents, such as serum proteins, total cholesterol, and bilirubin, fall within the range found in venous blood (Table 1). The absence of clotting is the most notable biochemical difference between menses and venous blood. What appear to be menstrual blood clots actually represent large samples of the aforementioned blood-tissue agglomerates.

In venous blood, clotting involves three broadly defined steps:

1. Prothrombin activator complex is formed in response to vessel or blood damage.

2. Prothrombin activator complex catalyzes the activation of prothrombin into the proteolytic enzyme, thrombin.

3. Thrombin cleaves fibrinogen into peptides, which polymerize into fibrin threads that enmesh platelets, blood cells, and plasma to form the clot itself.

Other coagulation factors participate in the process. Clot lysis requires the activation of plasminogen to plasmin, a proteolytic enzyme that digests fibrin threads in the blood clot. Unlike venous blood, menses is depleted of key clotting factors, has lower platelet counts and reduced platelet activity, but is high in fibrinolytic activity (Table 1). Prothrombin, free thrombin, fibrinogen, and fibrin are absent from menstrual blood (11 -13). Instead, high levels of tissue plasminogen activator and fibrin degradation products are found (11,13,14). The plasmin present in menses, though comparable in concentration to that of venous blood, is no longer fibrinolytically active. Moreover, platelets in menses differ from platelets in venous blood in that they fail to aggregate in response to stimuli or to produce chemical messengers involved in the clotting response (15). These data suggest that clots initially formed in endometrial blood are degraded during menstruation.

Besides these differences in coagulation components, menses but not venous blood contains matrix metalloproteinases (MMPs), enzymes that catalyze endometrial breakdown through proteolysis of the stromal extracellular matrix (16-19). Examples include MMP-1 (interstitial collagenase), MMP-2 (gelatinase-A), MMP-3 (stromelysin 1), MMP-9 (gelatinase-B), and MMP-10 (stromelysin-2). MMPs are secreted as inactive proenzymes. In the endometrium, they are expressed and activated during the late secretory and menstrual phases of the cycle in response to progesterone withdrawal, the hormonal trigger for menstruation (20,21).

The physical properties of menses are highly dependent on its composition. Because the proportions of proteins, lipids, mucins, blood, and tissue-derived constituents vary temporally over the course of menstrual flow, it is not meaningful to cite average values for physical properties such as viscosity and elasticity. Rather, the following discussion highlights the tremendous range in these properties.

For example, menses viscosity (measured at a given shear rate) varies dramatically, as much as an order of magnitude in a single set of samples (data not shown). The thinnest samples, collected when menstrual flow was greatest, had a viscosity similar to that of venous blood; samples collected during times of low menstrual flow were more viscous; indeed, some could be described as more gelatinous than liquid in nature. It is fair to say that a large proportion of menses samples are considerably more viscous than blood or water—about four times as viscous as venous blood and 35 times as viscous as water (22).

The elasticity of menses also varies considerably. Spinnbarkeit, a clinical term applied to the elasticity of cervical mucous, can be used describe the elasticity of menses. As background, cervical mucous responds to estrogen with a

Figure 3 Spinnbarkeit test for menses elasticity. (See color insert p. 7.)

Figure 3 Spinnbarkeit test for menses elasticity. (See color insert p. 7.)

decrease in viscosity, which results in a clinically important observation that the elasticity of cervical mucous, i.e., the length of a strand formed when cervical mucous is extended, is greatest at the time of ovulation. (This observation that can be helpful in either avoiding or planning conception.) Spinnbarkeit, or the ability to form a strand, can also be used to measure the elasticity of menses (Fig. 3). The length of a "strand" formed when menses fluid is rapidly extended often reaches 30 mm before it breaks; however, strand length can range from 0 mm (no elasticity) to 70 mm (more elastic than maple syrup) (23).

In conclusion, menses differs in important respects from venous blood because its constituents are derived from endometrial breakdown and passage through the vaginal tract. Besides red blood cells and serum constituents, menses contains tissue agglomerates, endometrial proteases, and cervico-vaginal secretions not found in venous blood. Menses is also depleted of certain clotting factors. Consequently, menses exhibits a broader range in physical characteristics and chemical composition than does venous blood.

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  • petteri p
    What are the constitute of menstral cycle?
    3 months ago
  • amina
    What are composition of mense?
    2 months ago

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