Amniotic Fluid (FLUID contain tokens of amniotic epithelium and)

AMNIOTIC FLUID contain tokens of amniotic epithelium and sometimes leukocytes (Daniel, Vinogradova). In healthy pregnant women and women in labor, amniotic fluid is in the vast majority of cases sterile (Aleksapolsky). In pathological cases (leukorrhea, febrile states, albuminuria, syphilis, etc.), a significant number of leukocytes, lymphocytes, often deformed erythrocytes, and microorganisms (streptococci, staphylococci, and rod-shaped forms) appear in it (Vinogradova). - The amount of amniotic fluid even within physiological limits can be very variable. In general, it is accepted that in the first 5 months, along with the growth of pregnancy, there is a gradual increase in the amount of fluid compared to the size of the embryo, and then the weight of the fetus increases faster, and the fluid becomes relatively less (Spiegelberg, Runge, Lepage). According to precise measurements by Charlotte Lehn, the amount of amniotic fluid by the end of normal pregnancy averages 1,070 g (in primiparae 1,000 g, in multiparae 1,200 g). The relationship between the amount of amniotic fluid and a number of factors - length and weight of the fetus, sex, size of the placenta, length of the umbilical cord, chemical composition of the fluid, etc. - has not been established. Cryoscopic study has shown that the freezing point of amniotic fluid ranges from -0.475° to -0.495°. Specific electrical conductivity on average (from 4 cases) is 0.0107 (in cm^-1 ohm^-1). Electromotive force in volts on average is 0.296. The study of the chemical composition of women's amniotic fluid was carried out by a number of authors, and at first the results were extremely contradictory. In 1877, the foundational work of Prochownik was published, whose data were accepted by everyone. Prochownik showed that the composition of amniotic fluid is characterized by a certain constancy with minor quantitative fluctuations (Prochownik's studies do not, however, give a complete determination of the chemical composition of amniotic fluid). Later, some other components of amniotic fluid were isolated: P₂O₇, sulfates, phosphorus, traces of magnesia, creatine, mucin, cholesterol, soaps, allantoin, protein (albumin, globulin) and many enzymes (pepsin, diastase, lipase, fibrin ferment) (Bruno Wolff). Vinogradova (1928) studied the inorganic residue of women's amniotic fluid. Based on chemical and spectral studies of 22 samples, the complete qualitative and quantitative composition of the fluid was obtained, the "probable" chemical composition was calculated, and the average content of amniotic fluid was derived. - Inorganic composition of amniotic fluid: sodium chloride 0.050-0.126%, potassium chloride 0.010-0.07%, magnesium sulfate 0.01895-0.03306%, calcium bicarbonate 0.49-1.56%, iron oxide 0.001-0.29%, phosphoric anhydride 0.00003-0.02198%, water 94.33-98.86%, organic substances in amniotic fluid range from 0.5% to 4.0%. These studies showed that the composition of amniotic fluid is distinguished by great constancy regarding inorganic substances with minor quantitative fluctuations. - During spectroscopic analysis (Goralevich and Vinogradova), in addition to ordinary elements, the appearance of a number of lines in the center of the violet part of the spectrum that could not be measured (constant flickering) was noted. Electrometric measurement of the calcined residue of the fluid established the ionization of air in the instrument's chamber, giving from 0.013 to 0.150 Maché units per 1 cm² of emitting surface. The found minimum amount of ionizing substance with a certain probability was attributed to the presence of radioactive substances - thorium or actinium salts. - In amniotic fluid, hormones of certain endocrine glands are also found in relatively significant quantities (Aranovich, Frank). Thus, per 1 liter of amniotic fluid there are about 300 M.U. (mouse units) of female sex hormone, and approximately these same amounts should be considered for the presence of prolan - the hormone of the anterior pituitary gland. Origin of amniotic fluid. In ancient times, it was believed that amniotic fluid originates from fetal secretions, urine, sweat (Empedocles, Galen, Hippocrates), as a result of delayed menstruation (Vesalius), from the ovary or from a follicle. Experimental works of the second half of the 19th century were extremely contradictory. Scanzoni and Matveyev considered the maternal organism to be the source of amniotic fluid and cited the transition of aromatic substances into amniotic fluid as proof. K. Braun, Preyer, and especially Jungbluth (K. Braun, Preyer, Jungbluth) attributed the production of amniotic fluid to the embryonic part of the placenta, from whence the fluid passes into the amniotic cavity via the finest capillaries (vasa propria Jungbluthi). Other authors, based on experimental work on the metabolic exchange between mother and fetus, do not allow for intrauterine urination of the fetus and attribute the formation of fluid mainly to transudation from maternal blood and partly only from placental vessels. In recent decades, thanks to new research of an anatomical-physical-biochemical nature and data obtained on their basis, the long-dominant but poorly substantiated point of view that amniotic fluid is formed as a result of mechanical suction of serum from maternal blood has been abandoned. Studies by a number of authors have established that amniotic fluid is a product of the secretory activity of the embryonic amniotic epithelium located at the site of the placenta, where special formations - vacuoles - were found, in which fluid accumulates and is emptied into the amniotic cavity. These cylindrical cells with vacuole inclusions, according to some authors, should be regarded as secretory cells. The regulation of accumulation and outflow of amniotic fluid still appears poorly elucidated. The physiological role of amniotic fluid is not fully elucidated. The mechanical significance of amniotic fluid is indisputable, since it promotes uniform stretching of the uterine walls, prevents adhesion of the fetus to the walls of the ovum and deformation of the infant's limbs, facilitating its movements and making them less sensitive for the mother. Amniotic fluid also balances the pressure of the uterus on the placenta and umbilical vessels. No less a role is played by amniotic fluid during childbirth: it promotes uniform expansion of the uterine cervix, moistens the birth canal, and as the so-called hindwaters keeps the uterus from complete contraction and premature disruption of placental circulation. The question of whether amniotic fluid serves as a nutrient for the fetus has not yet been definitively resolved. Experimental work and observations on the nutrition of embryos of lower animals can be a confirmation of these assumptions; the chicken embryo from the 17th day absorbs its fluid by hatching. Mammals (cow, pig, sheep, etc.) also, as a rule, absorb amniotic fluid from the second half of intrauterine life (Kistyakovsky, Dederlein). Kistyakovsky, Marschand, and Zaretsky proved the presence on the amnion in a number of animals (cows, pigs, mice, guinea pigs) of epithelial plaques with a high glycogen content, which then enter the stomach of the fetus. Zaretsky also studied the question of the delivery of carbohydrates to the developing animal organism and investigated the uterine mucosa in animals and women. In pregnant women, he always encountered grains and lumps of glycogen in decidual cells and outside them, mainly in the decidua serotina (basalis); in non-pregnant women, glycogen could not be detected. In the human placenta, according to Brindeau and Langhans, glycogen is contained throughout pregnancy; in the placental part of the amnion, Polano discovered a saccharifying enzyme, and thus it was possible to trace the pathway of glycogen influx from the maternal organism to the amnion and its cleavage under the influence of the saccharifying enzyme. In recent years, Bondy, Polano, and his students have proven the physiological significance of the amnion as an organ serving to deliver nutrition to the fetus. Precise chemical studies have discovered a number of lipoids and their breakdown products (fats, fat-like substances, fatty acids, soaps, glycerin, cholesterol) and a lipolytic enzyme in the parietal free amnion. In subamniotic tissues toward the decidua, a progressive increase in small fat droplets was found. Hence it follows that fat and glycogen are delivered to the fetus from the uterine mucosa. Approaching the amnion, these minute fat droplets, under the influence of lipolytic enzymes, break down into their components and enter the amniotic fluid. In the latter, the lipolytic enzyme was not found (Herman). Histological examination also revealed that up to the 5th month of pregnancy, fat droplets impregnate the upper layers of the fetus's skin, and then fat accumulation occurs in the upper sections of the small intestines (Polano). - Regarding the transition of protein substances to the fetus, there are still no exact data, but nevertheless, enzymes that break down proteins (chymosin) and a fibrin ferment were discovered in the amnion. The presence of many components of the protein molecule in amniotic fluid (by analogy with the transfer of fat and carbohydrates to the fetus) allows us to assume that protein particles can also be perceived by the fetus through the amniotic fluid.

S. Vinogradova

The presence of a specific and constant inorganic composition of the waters at all stages of pregnancy points to the subtle specificity of this fluid as a medium for the growing organism. It is known that the function of salts is no less important and diverse than the function of the organic components of food (Abderhalden), and therefore it must be recognized that amniotic fluid supplies the fetus not only with sugar and fat, but (with high probability) also with salts, proteins, and water. Furthermore, the presence in amniotic fluid of hormones and minimal doses of radioactive elements allows us to recognize their activating property. Thus, one can come to the conclusion that amniotic fluid is important in the development and birth of the fetus not only as a mechanical factor, but that it plays a definite role in the nutrition of the fetus and in the supply of energy for its rapid growth and development.