Development & Inheritance

• What are the main steps in the development of the ovum?

  Fertilization, pre-embryonic cleavage, and implantation

  
• Where does fertilization occur in the female reproductive system?

  In the uterine tubes (fallopian tubes)
• What prevents polyspermy during fertilization?

  The oocyte depolarizes the membrane and destroys sperm receptors
• What is formed at the point of fertilization?

  A single-celled diploid zygote
• What happens to the oocyte upon fertilization?

  It completes meiosis and becomes an ovum
• What can result from the release of more than one egg during ovulation?

  Fraternal (non-identical) twins
• What is gestation?

  The period of time required for full development of a fetus in utero

  
• What is the morula?

  A 16-cell structure formed after fertilization
• What is the blastocyst?

  A structure that contains an inner cell mass and an outer layer

  
• What do trophoblasts develop into?

  The chorionic sac and the fetal portion of the placenta
• What is totipotency in embryonic cells?

  The ability of each cell to differentiate into any cell type
• What hormone does the syncytiotropoblast secrete?

  Human chorionic gonadotropin (hCG)
• What does hCG do in the body during pregnancy?

  It directs the corpus luteum to continue releasing progesterone and estrogen

  
• What is implantation?

  The process where the blastocyst adheres to the endometrium

  
• What happens if implantation fails?

  The blastocyst is shed with the endometrial lining

  
• What is placenta previa?

  A condition where the placenta grows over the opening of the cervix
• What are the extra-embryonic membranes formed during the second week of development?

  The amnion, yolk sac, allantois, and chorion

  
• What does the epiblast and amnion do?

  They fill with amniotic fluid to protect the embryo
• What does the hypoblast and yolk sac provide to the embryo?

  Nutrients and primitive blood circulation
• What happens to the yolk sac during development?

  It diminishes into the allantois when the placenta takes over

  
• What is gastrulation?

  The process where totipotent cells differentiate into multipotent cells
• What are the three germ layers formed during gastrulation?

  Endoderm, mesoderm, and ectoderm

  
• What does the endoderm differentiate into?

  The gastrointestinal tract, liver, pancreas, and inner layer of the lungs
• What does the mesoderm differentiate into?

  The skeleton, muscles, connective tissue, heart, blood vessels, and kidneys
• What does the ectoderm differentiate into?

  The nervous system, sensory organs, epidermis, hair, and nails
• What are the changes in the maternal body during pregnancy, parturition, and breastfeeding?

  • Hormonal changes:
  • Human chorionic gonadotropin (hCG)
  • Progesterone
  • Estrogen
  • Changes during parturition:
  • Increased oxytocin
  • Relaxin for pelvic flexibility
  • Changes during breastfeeding:
  • Prolactin for milk production
  • Oxytocin for milk ejection

  
• What are the stages of gestation?

  1. Pre-embryonic stage
  2. Embryonic stage
  3. Fetal stage

  
• What are the key functions of the embryonic disc layers?

  • Epiblast and amnion: Protect the embryo with amniotic fluid
  • Hypoblast and yolk sac: Provide nutrients and primitive blood circulation

  
• What are the functions of the three germ layers formed during gastrulation?

  • Endoderm: Forms gastrointestinal tract, liver, pancreas, and lungs
  • Mesoderm: Forms skeleton, muscles, connective tissue, heart, blood vessels, and kidneys
  • Ectoderm: Forms nervous system, sensory organs, epidermis, hair, and nails

  
• What hormone is secreted by the placenta shortly after fertilization?

  Human Chorionic Gonadotropin (hCG)
• What is the role of hCG during early pregnancy?

  It maintains the corpus luteum to ensure progesterone production

  
• When do hCG levels peak during pregnancy?

  In the first trimester
• What is the function of progesterone during pregnancy?

  It maintains the uterine lining and prevents contractions
• What hormone prepares the breasts for milk production?

  Progesterone
• How does estrogen contribute during pregnancy?

  It stimulates uterine growth and enhances blood flow to the uterus
• What is the primary role of relaxin during pregnancy?

  To relax ligaments in the pelvis and soften the cervix
• What is the role of Human Placental Lactogen (hPL)?

  It adjusts the mother's metabolism to supply glucose and nutrients to the fetus
• What hormone stimulates uterine contractions during labor?

  Oxytocin
• How do prostaglandins contribute to labor?

  They soften and dilate the cervix and increase uterine sensitivity to oxytocin
• What happens to estrogen levels before labor?

  Estrogen levels increase significantly, enhancing uterine sensitivity to oxytocin