ex. 44 [embryonic development]

• fertilization: sperm penetrates egg and their nuclei fuses to form a single nucleus
• zygote: a diploid cell resulting from the fusion of two haploid gametes; a fertilized ovum.
• cleavage: mitotic division where cells get smaller and smaller without intervening growth periods
• gastrulation: the process of the formation of the three germ layers from the inner cell mass
• blastocyst: final product of cleavage stage, 3-5 day old embryo
• implantation occurs seven days after ovulation, blastocyst adheres to uterine wall over embryoblast area -> trophoblast secrete enzymes to break down endometrium to reach blood supply to help with implantation; complete twelve days after fertilization
• decidua basalis: part of endometrium below embryo
• decidua capsularis: part of endometrium on luminal face of uterus
• mesoderm

  • dermis
  • skeleton
  • all muscle tissue types
  • cartilage
  • blood vessels
  • kidneys and ureters
  • lymphoid organs and tissues
  • internal reproductive organs
  • serous membranes
  • adrenal cortex
• endoderm

  • respiratory, GI, urinary and reproductive tract epithelial linings
  • liver, gallbladder and pancreas
  • thymus, parathyroid, thyroid glands
• placenta

  A) decidua basalis

  B) placenta

  C) chorionic villi

  D) decidua capsularis

  E) maternal arteries

  F) maternal veins

  G) maternal portion of placenta (decidua basalis)

  H) fetal portion of placenta (chorion)

  I) umbilical arteries and veins

  J) fetal arteriole and venule

  K) chorionic villus w/ fetal capillaries

  L) maternal blood

  
• early embryonic development

  A) synctiotrophoblast

  B) cytotrophoblast

  C) amniotic cavity

  D) epiblast

  E) hypoblast

  F) blood-filled lacunae

  G) chorionic villus

  H) chorion

  I) amnion

  J) yolk sac

  K) extraembryonic mesoderm

  L) amniotic cavity

  M) ectoderm

  N) mesoderm

  O) endoderm

  P) allantois

  
• 4.5 week embryo

  A) decidua basalis

  B) chorionic villus

  C) amnion

  D) amniotic cavity

  E) yolk sac

  F) extraembryonic coelom

  G) chorion

  H) decidua capsularis

  
• early embryo development

  A) zygote

  B) morula

  C) early blastocyst

  D) implanting blastocyst

  E) embryoblast

  F) trophoblast

  
• embryoblast: the inner cell mass of the blastocyst that gives rise to the embryo
• trophoblast: flattened cells enclosing embryoblast
• chorionic villi: creates the placenta
• amnion: a membrane that surrounds the embryo and protects it from physical trauma, temp extremes, prevents adhesion during growth
• yolk sac: first blood cells originates here, seed gonadal tissue, forms part of digestive tube
• allantois: structural basis where mesoderm migrates to form umbilical cord
• ectoderm

  • epidermis and accessory skin structures
  • nervous system and special sense organs
  • oral cavity, nasal cavity and anal canal epithelia
  • adrenal medulla, pituitary and pineal glands