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18 Cards in this Set

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Fertilization --> Blastocyst (Intermediates)
-Fertilization -> Cleavage -> Blastula -> Blastomeres -> Morula (compaction) -> Blastocyst -> Occurs while surrounded by zona pellucida
Blastocyst Pathway
-Cleavage and blastocyst formation occurs on way to uterus
-Blastocyst hatches
-Blastocyst implants in wall of uterus
-Blastocyst secretes proteins that degrade zona pellucida -> Implantation
Human Chorionic Gonadotropin (hCG) - what is it secreted by, what are its 2 subunits, pregnancy tests
-Secreted by STB (trophoblast)
-hCG has alpha- and beta-subunits; alpha-subunit common to several hormones, beta-subunit unique to hCG
-Pregnancy tests accurate within 7 days of fertilization via sensitive RIA (radioimmunoassay) for blood beta-hCG
-Home test kits less sensitive colorimetric assays- soon after missed period, can detect beta-hCG in urine
If Fertilization Occurs, what happens to hCG and STB
-STB becomes source of hCG
-hCG stimulates continued progesterone secretion by Corpus Luteum
-No menses (menstrual flow)
-First missed period and pregnancy
Changes in the Uterine Mucosa
-Early developing follicles secrete estrogen that support growth in thickness of endometrium lining, length of glandular endometrium, thickening of blood vessels
-Ovulation: remnants of ovarian follicle become corpus luteum which secrete progesterone and continue glandular and vessel elongation and increase sensory activity of the endometrium
-Implanted embryo: source of HcG – feeds back to maternal bloodstream which stimulates ongoing growth for hospital environment of embryo
If No Fertilization Occurs, what happens to hCG and corpus luteum
-No hCG
-Corpus luteum regresses, progesterone falls
-Menses occur
The pituitary gland secretes gonatropins (hormones) of LH and FSH - what does each affect
FSH - Maturation of follicle and ovulation
LH - Maturation of follicle, ovulation, and corpus luteum
Implantation - Blastocyst pathway and resulting formations (2)
-Blastocyst (loosens the matrix and cause degeneration of zona pellucida) hatches from Zona Pellucida (fibrous mixture of glycoproteins)
-Blastocyst attaches at pole containing inner cell mass
-Outer trophoblastic cells proliferate and fuse to form outer syncytium
-Results in formation of Inner Cytotrophoblast (CTB) and superficial Syncytiotrophoblast (STB)
Syncytium and its components' functions
-Large mass of cytoplasm containing nuclei of many cells formed by fusion of many uninucleate cells -> merge and form tissue layers:
-Cytotrophoboast (CTB): function is to attach the baby to the mother's uterus. It provides the anchor
-Syncytiotrophoblast (STB): persist up to placenta (respiratory/waste exchange for fetus)
-Both are part of trophoblast
Implantation - Role of STB (LOOK AT SLIDES 13-15)
-STB is an Invasive, motile layer
-STB breaks down endometrial epithelium and degrades stroma
-Maternal Blood Vessels open, bathing STB
-STB continues to invade and expand, forming irregular surface with Lacunae (bathed by RBC) = surface irregularities


STB: highly mobile, sends out projections into CT; causes rupture of blood vessels so that maternal blood is pouring onto STB surface
o Meanwhile STB is also burrowing into and degrading the wall of female reproductive tract
o Developing system closely attached with maternal blood vessels -> source of nutrients, food, oxygen and expels fetus’ CO2, nitrogenous wastes, etc
Bilaminar Disc
Inner cell mass forms 2 layers spontaneously during STB's activities: epiblast (columnar) and hypoblast (cuboidal) -> known as Bilaminar Disc
Peculiarities of Human Implantation (3)
-Hemochorial Placenta-free surface of pre-embryo (chorion) bathed directly in maternal blood
-Human implantation is Interstitial- pre-embryo completely surround by maternal tissue
-Necessary or maternal blood will leak into lumen of reproductive tract (uterine cavity)
Abnormal Implantation, Ectopic Implantation, and most common type of abnormal implantation
-An Abnormal Implantation is one that occurs in any site other than the upper, posterior portion of the uterine body.
-An Ectopic Implantation (pregnancy) is any abnormal implantation where development occurs outside of the uterine lumen.
-About 95% of all abnormal implantations are ectopic implantations but the two are not synonymous
-Placenta Previa is the most common type of abnormal implantation
Placenta Previa and Solution
-Placenta forms across “internal os” of cervix. -During normal birth, first baby, then placenta exits so that while in transit, baby is still breathing via placenta. With placenta previa, placenta can detach as birth occurs, and the fetus will suffocate.
-Solution = Caesarian Section
Ectopic Pregnancy - most common
-Defined as an Implantation where development of conceptus occurs outside uterine lumen
-About 95% of ectopic pregnancies occur in the Uterine Tubes, but tubal pregnancy and ectopic pregnancy not synonymous
-Rest of ectopics occur at scattered sites, e.g., mesentery, rectouterine pouch, ovary, etc.
Predisposing Factors to Ectopic Pregnancy (3)
-Prior pelvic surgery (e.g. appendicitis) -> may have compromised functional tubes
-Past history of use of IUD (Intrauterine birth control device, which prevents implantation of an embryo into the uterus should fertilization occur.)
-Pelvic inflammatory disease (PID): explains why ectopic pregnancies are more prevalent in urban populations, e.g., Chlamydia trachomatis infections, syphilis, gonorrhea
Signs and Symptoms of Rupture (3)
-Reproductively competent, sexually active, sudden onset of unilateral lower quadrant pain
-Distended firm abdomen with rebound tenderness -> indicates bleeding out into abdomen
-Normal temp, tachycardia (fast heart rate), decreased BP, decreased hematocrit, positive beta-hCG
Treatment
-Early Ultrasound when pregnant establishes implantation site and can rule out or diagnose ectopic pregnancy
-If unruptured, then use of Methotrexate (antimetabolite drug that inhibits DNA synthesis, then need to remove compromised tube) or surgical removal and repair
-If ruptured, then Surgical Removal and repair