Pregnancy test introduction.
[1]. Pregnancy test is the test used to detect or confirm pregnancy. The basis of pregnancy tests is to determine the presence of the human chorionic gonadotropin (hCG) in the urine of woman suspected for pregnancy.
[2]. Both biological and immunological tests are available to determine the presence of hCG in the urine of the pregnant woman.
Biological tests.
These tests are performed by using experimental animals. The biological tests for pregnancy can be performed only after 2 or 3 weeks of conception so that, the concentration of hCG in urine is sufficient to show the result.
Aschheim-Zondek test.
[1]. Aschheim-Zondek test was the first test invented for confirming the pregnancy. It depends upon the ovarian changes in immature mice caused by hCG. The immature mice do not ovulate naturally.
[2]. Ovulation occurs only if hCG is injected. 2 mL of urine from the woman suspected for pregnancy is injected daily for 2 days into the immature mice. 5 days after injection of urine, the mice are killed.
[3]. The ovaries are examined for the presence of corpora lutea (plural for corpus luteum) and hemorrhages, which indicates ovulation. Ovulation is due to the presence of hCG in urine.
Kupperman test.
[1]. Kupperman test is the modification of Aschheim-Zondek test, in order to save time. In this, an immature rat is used instead of immature mice.
[2]. About 2 mL of urine is injected subcutaneously into immature rat and ovarian changes are observed after 6 hours.
[3]. If the urine is injected intraperitoneally, the ovarian changes can be observed within 2 hours.
Friedman test.
10 to 15 mL of urine is injected intravenously into rabbit and ovulation is observed by examining the ovaries after 48 hours.
Hogben test.
About 20 to 30 ml of urine is concentrated and injected into the dorsal lymph sac of South African toad, Xenopus levis. If hCG is present in the urine, it causes ovulation after 12 hours.
Galli-Mainini test.
2 mL of urine is injected into the male amphibian (toad or frog). hCG in urine causes expulsion of spermatozoa within 2 hours. Biological tests are outdated after the development of immunological tests.
Disadvantages of Biological Tests.
Biological tests for pregnancy are replaced by immunological tests because of several disadvantages:
1. The biological test require animals.
2. Tests can be performed only after 2 to 3 weeks of pregnancy so that sufficient quantity of hCG is excreted in urine.
3. Results are not obtained quickly; one has to wait for 2 to 48 hours.
4. Tests involve tedious procedures such as sacrificing the animals.
Immunological test.
Presence of hCG is also determined by using immunological techniques. Immunological tests are based on double antigen-antibody reactions. Commonly performed immunological test is known as Gravindex test.
Principle of Immunological test.
Principle is to determine the agglutination of sheep RBCs coated with hCG. Latex particles could also be used instead of sheep RBCs.
Requirement for Immunological test.
1. Antiserum from Rabbit.
[1]. Urine from a pregnant woman is collected and hCG is isolated. This hCG is injected into a rabbit. The rabbit develops antibodies against hCG.
[2]. The antibodies are called hCG antibody or anti-hCG. The rabbit’s blood is obtained and serum is separated.
[3]. The serum containing hCG antibody is called rabbit antiserum or hCG antiserum. It is readily available in the market.
2. Red Blood Cells from Sheep.
RBCs are obtained from sheep blood and are coated with pure hCG obtained from urine of the pregnant women. Nowadays, instead of sheep RBCs, the rubberized synthetic particles called the latex particles are used.
3. Urine.
Fresh urine sample of the woman, who needs to confirm pregnancy is used for Gravindex test.
Procedure of Immunological test.
1. One drop of hCG antiserum is taken on a glass slide. One drop of urine from the woman who wants to confirm pregnancy is added to this and both are mixed well.
2. Now, one drop of latex particles is added to this and mixed.
Observation & result of Immunological test.
Result is determined by observing the agglutination of latex particles added to mixer of hCG antiserum and woman’s urine.
Absence of Agglutination of Latex Particles.
[1]. If hCG is present in urine, it is agglutinated by antibodies of antiserum and all the antibodies are fully used up. No free antibody is available. Agglutination of hCG molecules by antibodies is not visible because it is colorless.
[2]. Later when latex particles are added, these particles are not agglutinated because, free antibody is not available. Thus, absence of agglutination of latex particles indicates that the woman is pregnant.
Presence of Agglutination of Latex Particles.
[1]. If urine without hCG is mixed with antiserum, the antibodies are freely available. When latex particles are added, the antibodies cause agglutination of these latex particles.
[2]. Agglutination of latex particles can be seen clearly even with naked eye. Thus, presence of agglutination of latex particles indicates that, the woman is not pregnant .
Advantages of Immunological test for pregnancy.
1. Immunological tests are more accurate.
2. Result is obtained quickly within few minutes.
3. These tests can be carried out very easily. The procedure is not cumbersome, as in the case of biological tests.
4. Immunological tests can be performed on 5th day of conception. By biological methods, the tests can be performed only after 2 or 3 weeks of conception. It is because, the concentration of hCG required for producing changes in the animals is excreted in urine only after 2 or 3 weeks of pregnancy.
5. Recently available immunological tests are more sensitive and involve single step method. Test kit is available in the form of cards. These pregnancy test cards can be used even in the first few days of conception. Most sensitive test can detect hCG level as low as 20 mIU/mL.
Development of Mammary glands.
Mammary gland at birth.
At the time of birth, mammary gland is rudimentary and consists of only a tiny nipple and few radiating ducts from it.
Mammary gland at Childhood.
Till puberty, there is no difference in the structure of mammary gland between male and female.
Mammary gland at Puberty.
[1]. At the time of puberty and afterwards there is a vast change in the structure of female mammary gland due to hormonal influence.
[2]. The beginning of changes in mammary gland is called thelarche. It occurs at the time of puberty, just before menarche . At puberty, there is growth of duct system and formation of glandular tissue.
[3]. During every sexual cycle, at the time of menstruation there is slight regression and in between the phases of menstruation, proliferative
changes occur. On the whole, progressive enlargement occurs, which is also due to the deposition of fat.
Mammary gland during Pregnancy.
[1]. During pregnancy, the mammary glands enlarge to a great extent accompanied by marked changes in structure.
[2]. During first half of pregnancy, the duct system develops further with appearance of many new alveoli. No milk is secreted by the gland now.
[3]. During the second half, there is enormous growth of glandular tissues and the development is completed for the production of milk just before the end of gestation period.
Role of Hormone in Growth of Mammary glands.
Various hormones are involved in the development and growth of breasts at different stages:
1. Estrogen.
2. Progesterone.
3. Prolactin.
4. Placental hormones.
5. Other hormones.
1. Growth of Ductile System by Estrogen hormone.
Estrogen causes growth and branching of duct system; so the normal development of duct system in breasts at puberty depends upon estrogen. Estrogen is also responsible for the accumulation of fat in breasts.
2. Growth of Glandular Tissue by progesterone hormone.
The development of stroma of the mammary glands depends upon progesterone activity. Progesterone also stimulates the development of glandular tissues.
3. Milk Secretion by Prolactin hormone .
[1]. Prolactin is necessary for milk secretion. However, it also plays an important role in growth of mammary glands during pregnancy. Normally, prolactin is inhibited by prolactin-inhibiting hormone secreted from hypothalamus.
[2]. However, prolactin secretion starts increasing from 5th month of pregnancy. At that time, it acts directly on the mammary glands and causes proliferation of epithelial cells of alveoli.
4. Placental Hormones.
Estrogen and progesterone secreted from placenta are essential for further development of mammary glands during pregnancy. Both the hormones stimulate the proliferation of ducts and glandular cells during pregnancy.
5. Growth Hormone, Thyroxine & Cortisol .
[1]. Growth hormone, thyroxine and cortisol enhance the overall growth and development of mammary glands in all stages. Relaxin also facilitates the development of mammary glands.
[2]. It is secreted by corpus luteum, mammary glands and placenta. Its major function is to facilitate dilatation of cervix during labor .
Lactation.
Lactation means synthesis, secretion and ejection of milk. Lactation involves two processes:
1. Milk secretion.
2. Milk ejection.
1. Milk secretion.
Synthesis of milk by alveolar epithelium and its passage through the duct system is called milk secretion.
Milk secretion occurs in two phases:
1. Initiation of milk secretion or lactogenesis.
2. Maintenance of milk secretion or galactopoiesis.
1. Initiation of Milk Secretion or Lactogenesis.
[1]. Although small amount of milk secretion occurs at later months of pregnancy, a free flow of milk occurs only after the delivery of the child. The milk, which is secreted initially before parturition is called colostrum.
[2]. Colostrum is lemon yellow in color and it is rich in protein (particularly globulins) and salts. But its sugar content is low. It contains almost all the components of milk except fat.
Role of hormones in Lactogenesis.
[1]. Prolactin is responsible for lactogenesis. During pregnancy, particularly in later months, large quantity of prolactin is secreted. But the activity of this hormone is suppressed by estrogen and progesterone secreted by placenta. Because of this, lactation is prevented during pregnancy.
[2]. Immediately after the delivery of the baby and expulsion of placenta, there is sudden loss of estrogen and progesterone. Now, the prolactin is free to exert its action on breasts and to promote lactogenesis.
2. Maintenance of Milk Secretion or Galactopoiesis.
Galactopoiesis depends upon the hormones like growth hormone, thyroxine and cortisol, which are essential for continuous supply of glucose, amino acids, fatty acids, calcium and other substances necessary for the milk production .
Role of hypothalamus in Galactopoiesis.
[1]. Galactopoiesis occurs till 7 to 9 months after delivery of child provided feeding the baby with mother’s milk is continued till then. In fact, the milk production is continued only if feeding the baby is continued. Suckling of nipple by the baby is responsible for continuous milk production.
[2]. When the baby suckles, the impulses from touch receptors around the nipple stimulate hypothalamus. It is suggested that hypothalamus releases some prolactin-releasing factors, which cause the prolactin secretion from anterior pituitary.
[3]. Prolactin acts on glandular tissues and maintains the functional activity of breast for subsequent nursing.
2. Milk ejection.
[1]. Milk ejection is the discharge of milk from mammary gland. It depends upon suckling exerted by the baby and on contractile mechanism in breast, which expels milk from alveoli into the ducts.
[2]. Milk ejection is a reflex phenomenon. It is called milk ejection reflex or milk let-down reflex. It is a neuroendocrine reflex.
Effect of Lactation on Menstrual Cycle .
[1]. Woman who nurses her child regularly does not have menstrual cycle for about 24 to 30 weeks after delivery. It is because, regular nursing the baby stimulates prolactin secretion continuously. Prolactin inhibits GnRH secretion resulting in suppression of gonadotropin secretion.
[2]. In the absence of gonadotropin, the ovaries become inactive and ovulation does not occur. When the frequency of nursing the baby decreases (after about 24 weeks) the secretion of GnRH and gonadotropins starts slowly. When sufficient quantity of gonadotropins is secreted, the menstrual cycle starts.
Breast Milk .
Breast or human milk forms the primary source of nutrition for infants.
Composition of Breast Milk.
Breast milk contains about 88.5% of water and 11.5% of solids. Important solids are lactose, lactalbumin, iron, vitamins A and D and minerals.
Advantages of breast Milk.
[1]. Breast milk is always considered superior to animal milk (cow milk or goat milk) because it consists of sufficient quantity of all the substances necessary for infants like iron, vitamins and minerals.
[2]. Besides nourishment of infant, the breast milk also provides several antibodies, which help the infant resist the infection by lethal bacteria. Even some neutrophils and macrophages are secreted in milk. These phagocytic cells protect the infant by destroying microbes in the infant’s body.
Disadvantages of Animal Milk.
1. It causes irritation of GI tract and anemia.
2. Excess proteins and fats in animal milk are difficult to digest and absorb by the infants.
3. High content of casein is harder to digest resulting in GI bleeding and anemia.
4. High concentrations of sodium and potassium in animal milk causes overstraining of immature kidneys in infants.
5. Low iron content in animal milk develops iron deficiency anemia.
6. It has low content of vitamins and essential fatty acids.
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