Chapter 43. Hormonal Balance and Tests For Pregnancy - Review of Medical Embryology Book

BEFORE IMPLANTATION, MAINTENANCE OF PREGNANCY is assured by the ovarian and pituitary hormones
AFTER PREGNANCY, HORMONAL CONTROL OF PREGNANCY is assured by the combined action of the pituitary, ovarian, and placental hormones

Protein hormones are human chorionic gonadotropic hormone (hCG), human chorionic somatomammotropic hormone (hCS), or placental lactogen (hPL)
Steroid hormones: progesterone (from maternal cholesterol or pregnenolone) and estrogen (from 19-carbon precursors)

Chorionic gonadotropins are discernible very early, several days after nidation
Although the levels of estrogen and progesterone increase regularly during pregnancy until term, the gonadotropins, after reaching their peak on about day 60, decrease and are maintained at a relatively low level until the end of pregnancy

Test for pregnancy: biologic diagnosis of pregnancy is based on the detection of chorionic gonadotropins

BIOLOGIC TEST IN ANIMALS can be made in a variety of animal species, namely, the rat, the mouse, the rabbit, the frog, and even the toad. Injected gonadotropins provoke "characteristic" changes in the genital tracts of the animals. As seen in the genital tract of the injected virgin female rabbit

A urine or blood sample from a woman suspected of being pregnant is injected into the rabbit, and its genital tract is examined about 36 hours later

A positive reaction reveals congestion and hyperemia of the uterine horns and one or more hemorrhagic follicles are seen in the rabbit ovaries

IMMUNOLOGIC TEST: the existence of chorionic gonadotropins in the urine of a pregnant female can be demonstrated by anitgonadotropic serum, obtained by immunization of an animal against human gonadotropin

Negative or control reaction: if agent "a" and agent "b" are mixed, antibodies in the serum agglutinate the red blood cells through the gonadotropins which are attached, and this reaction is directly visible on a slide or in a test tube
Positive or no agglutination reaction: if several milliliters of urine containing free gonadotropins from a pregnant woman are mixed with reactive agent "a," these gonadotropins block the serum "a" antibodies and prevent them from agglutinating the red blood cells with the agent "b" on it
Currently, the red blood cells of reactive agent "b" have been replaced by the use of inert particles such as latex, which serve the same role and have the added advantage of not altering or degrading with time

Hormonal equilibrium gives one an idea of the progress of the pregnancy, but also allows the diagnosis of anomalies, particularly of placental degeneration
In hydatidiform mole and its malignant transformation, the chorioepithelioma, chorionic gonadotropins are abnormally high