uterus

Examples of uterus in the following topics:

• Female Reproductive Anatomy

  • Internal female reproductive structures include ovaries, oviducts, the uterus, and the vagina.
  • The embryo is moved toward the uterus for further development.
  • The uterus supports the developing embryo and fetus during gestation.
  • The thickest portion of the wall of the uterus is made of smooth muscle.
  • Contractions of the smooth muscle in the uterus aid in passing the baby through the vagina during labor.

• Labor and Birth

  • Labor is the physical effort of expulsion of the fetus and the placenta from the uterus during birth (parturition).
  • At the same time, the placenta releases prostaglandins into the uterus, increasing the contractions.
  • A positive feedback relay occurs between the uterus, hypothalamus, and the posterior pituitary to assure an adequate supply of oxytocin.
  • During stage two, the baby is expelled from the uterus with the umbilical cord still attached.
  • The uterus contracts and the mother pushes as she compresses her abdominal muscles to aid the delivery.

• Infertility

  • A common type of assisted reproductive technology is in vitro fertilization (IVF) where an egg and sperm are combined outside the body and then placed in the uterus.
  • Eggs are obtained from the woman after extensive hormonal treatments that prepare mature eggs for fertilization and prepare the uterus for implantation of the fertilized egg.
  • When the embryos have reached the eight-cell stage, one or more is implanted into the woman's uterus.

• Contraception and Birth Control

  • Barrier methods such as condoms, cervical caps, and diaphragms serve to block sperm from entering the uterus, thereby preventing fertilization.
  • IUDs are inserted into the uterus where they establish an inflammatory condition that prevents fertilized eggs from implanting into the uterine wall .
  • Tubal ligation or tubectomy is a surgical procedure for sterilization in which a woman's fallopian tubes are clamped and blocked, or severed and sealed; either method prevents eggs from reaching the uterus for fertilization.
  • An intrauterine device, or IUD, is implanted inside a woman's uterus, causing the uterus to respond with slight inflammation.

• The Evolution of Reproduction

  • In mammals, there are separate openings for the systems in the female and a uterus for support of developing offspring.
  • Depending on the type of species, there are differences in the uterus.
  • In species that produce large numbers of offspring, the uterus has two chambers.
  • In other species that produce one offspring, such as in primates, there is a single uterus.

• Female Hormones

  • Progesterone maintains the endometrium, the lining of the uterus, to help ensure pregnancy.
  • If pregnancy implantation does not occur, the lining of the uterus is sloughed off, a process known as menstruation.
  • The uterus is again being prepared to accept a fertilized egg, should it occur during this cycle.
  • If no fertilized egg is implanted into the uterus, the corpus luteum degenerates and the levels of estrogen and progesterone decrease.

• Pineal Gland and Gonads

  • Estrogen increases at the time of puberty, causing the growth of the uterus and vagina.
  • It prepares the lining of the uterus for implantation of a fertilized egg and allows for complete shedding of the endometrium at the time of menstruation.

• Human Gestation

  • When fertilized (at conception), the egg, now known as a zygote, travels through the oviduct to the uterus .
  • The developing embryo must implant into the wall of the uterus within seven days or it will deteriorate and die.
  • This ensures adequate levels of progesterone that will maintain the endometrium of the uterus for the support of the developing embryo.

• Fertilization

  • The zygote divides to form a blastocyst and, upon entering the uterus, implants in the endometrium, beginning pregnancy.

• Hormonal Regulation of the Reproductive System

  • The uterine smooth muscles are not very sensitive to oxytocin until late in pregnancy, when the number of oxytocin receptors in the uterus peaks.
  • Stretching of tissues in the uterus and cervix stimulates oxytocin release during childbirth.