[HISTO] Pregnancy & Lactation

• ovum is expelled into peritoneal cavity
• ciliary motion at fimbriated ends of fallopian tubes creates a slow current towards the tube opening called the ostium
• ovum is suspended at metaphase 2
• sperm cells penetrate the egg through the acrosomal reaction
• fertilization occurs mainly at the ampulla of the uterine tube
• after the entry of the sperm, there are cortical granules that empty their contents in the perivitelline space and this action blocks polyspermy
• sperm transport is aided by prostaglandins from the semen and oxytocin released during orgasm causing the reverse peristalsis of the uterus
• orgasm also temporarily opens the cervix
• fallopian tube secretions are the source of nutrition for the early embryo
• blastocyst implantation happens at around 5-7 days after ovulation
• trophoblastic cells invade the endometrium
• implantation bleeding is vaginal bleeding observed during implantation that is usually mistaken for menses. usually short and the amount of blood does not increase in the following days
• trophoblast tumors are from the trophoblast invading the endometrium during the blastocyst implantation
• trophoblasts are one of the most aggressive and highly invasive cells of the human body
• choriocarcinoma is a cancer or malignancy arising from trophoblasts
• trophoblastic tumors metastasize early and widely
• ectopic pregnancy means that implantation occurred outside of the uterine cavity
• only around 98% of the ovum is captured by the fallopian tube and 2% can be implanted outside of the uterine cavity and fallopian tube
• ectopic pregnancy is most commonly found in the fallopian tube
• placental hormones: hCG, progesterone, estrogen, and human somato-mammotropin
• hCG is secreted by the trophoblast cells of the blastocyst and has LH-like effects
• the placenta can secrete adequate amounts of progesterone
• after ovulation, fertilization will take place, followed by implantation after 5-7 days
• once the blastocysts invade the endometrium, it will start to produce hCG
• hCG will maintain the corpus luteum in order for it to not involute
• if fertilization did not happen, there will be no embryo or a blastocyst implanting, no hCG, the corpus luteum will involute. thus menstruation will occur
• pregnancy tests rely on detecting hCG from the urine or blood samples of the female which can be detected 8-9 days post ovulation
• hCG -> maintains corpus luteum -> secretes progesterone and estrogen -> maintains secretory endometrium (decidual cells) and therefore prevents menstruation
• in males, hCG has LH-like effects that stimulate testosterone production in testis
• sources of progesterone: corpus luteum, syncytiotrophoblasts, and placenta
• effects of progesterone

  prevents uterine contractions, increases fallopian tube sections, and causes decidual cells to develop in the endometrium
• sources of estrogen: syncytiotrophoblasts and placenta
• effects of estrogen


  breast ductal structure development and breast enlargement, external genitalia enlargement, uterine enlargement, and pelvic ligament relaxation
• human chorionic somatomammotrophin sources: syncytiotrophoblasts
• effects of human chorionic somatomammotrophins


  somato - decreases maternal insulin sensitivity

  mammo - helps in the development of the breasts
• gestational diabetes


  decrease in insulin sensitivity that becomes exaggerated, causing abnormally increased maternal blood glucose levels
• in gestational diabetes, there is a condition called fetal macrosomia, where the baby is much bigger than usual
• relaxin sources: corpus luteum and placenta
• effects of relaxin: relaxes the pelvic ligaments
• corticosteroid effects are anti-inflammatory agents