PRELIM - Oral Histology

• Oral Cavity - it is the space bounded by the lips anteriorly, cheeks laterally, floor of the mouth inferiorly, and the pharynx superiorly
• 2 compartments of oral cavity: oral vestibule and oral cavity proper
• oral vestibule - bounded facially: mucosa, labially: mucosa of the lips, bucally: mucosa of the lips, orally: alveolar mucosa, gingiva, and facial surfaces of the teeth
• oral cavity proper - bounded anterolaterally: oral surfaces of the teeth and gingiva, cranially: mucosa of the hard and soft palate, caudally: mucosa of the tongue and floor of the mouth, posteriolaterally: anterior pillar of the fauces and tonsils
• Enumerate the lingual papillae

  
  

  filiform papilla - it has no taste function

  fungiform papilla - it is for the perception of sweet and salty taste

  foliate papilla - it is for the perception of sour taste

  circumvallate papilla - it is for the perception of bitter taste
• enumerate the paraoral tissues

  lips, cheeks, teeth and its supporting structures, tongue, floor of the mouth, floor of the mouth, tonsils, salivary gland
• functions of the paraoral tissues

  Ingestion, Mastication, Deglutition, Speech, Digestion, Respiration, Protection, Taste
• embryology

  • The branch of biology and medicine concerned with the study of embryos and their development.
• embryo

  • An unborn or unhatched offspring in the process of development.
• Fertilization occurs in the ampulla of the uterine tube
• fertilization

  the union of the sperm and ovum that would produce a zygote
• zygote

  the product of the fertilization/ the product of the union of the sperm and ovum
• 3 stages in human development:

  Period of the ovum

  Period of the embryo

  fetal period
• proliferative period

  
  

  Fertilization to two weeks.

  In that two weeks time, implantation has taken place
• Period of the embryo/ embryonic period

  • Weeks 2 to 8
  • That is when all the organ systems have been formed all of the organ systems and cells are there and the heart begins to beat.
• Period of the fetus/ fetal period

  
  

  Weeks 8 to 36

  Period of maturation of the different organ systems
• Law of Differentiation Growth and Development

  • not all cells will develop at the same time
• the sperm undergoes:

  
  

  Capacitation process

  acrosomal reaction
• Capacitation process

  • glycoprotein coat and seminal plasma protein are removed from the spermatozoon head.
• Acrosomal reaction

  • hyaluronidase and trypsin-like substance are released to penetrate the oocyte barriers
• The oocyte finishes the 2nd meiotic division and becomes the female pronucleus.
• The head of the sperm separates from the tail and becomes the male pronucleus.
• During fertilization, the spermatozoa must penetrate the ff:

  • corona radiata
  • Zona pellucida
  • Oocyte cell membrane
• Results of fertilization:

  • Restoration of diploid number of chromosomes
  • determination of chromosomal sex
  • initiation of cleavage
• Embryoblast - Inner cell mass

  Give rise to the embryo
• Trophoblast - Outer cell mass

  Would be the future placenta
• cell layers of throphoblast

  • cytotrophoblas - flattened cell; inner cell layer
  • syncytiotrophoblast - outer cell layer
• Proliferative Period

  • Formation of the bilaminar germ disc

  - Two layers: Embryonic Endoderm & Embryonic Ectoderm
• Embryonic Period

  • Formation of the primitive streak
• Trigeminal Germ Disc:

  3 layers

  • Embryonic endoderm
  • Embryonic ectoderm
  • Embryonic mesoderm
• Neural crest is important because this is where ectomesenchymal cells will come from
• ectomesenchymal cells are one of the primordium of the teeth
• ectoderm and ectomesenchyme will give rise to the teeth

  • ectoderm=>neural crest=> ectomesenchyme
• neural tube will give rise to the future CNS
• Mesodermal germ layer gives rise to muscular tissue, connective tissue, the bone
• Endodermal germ layer gives rise to digestive system
• Stomodeum- future oral cavity

  Lined by 2 cell layer: ectoderm and endoderm called the oropharyngeal membrane.
• Rathke’s pouch

  • Anterior to stomodeum and oropharyngeal membrane
  • Place for future brain
• Branchial Arches (internally) Pharyngeal Pouches (externally) - Gives rise to structures of the head and neck area
• Mandibular arch

  • First branchial arch
  • 2 mandibular processes
  • 2 maxillary processes
  • Future ear area