Dental Embryology, Histology, and Anatomy Practice test 2023

Dental Embryology, Histology, and Anatomy Practice test 2023 Embryology - study of prenatal development Prenatal development - Begins: start of pregnancy Until: birth of child Three periods of prenatal development - 1. Preimplantation 2. Embryonic 3. Fetal What trimester do each period fall into? - 1. Preimplantation: 1st week - 1st trimester 2. Embryonic: 2nd - 8th week - 1st trimester 3. Fetal period: 3rd-9th month - 2nd and 3rd trimester Primordium - earliest indication of a part or an organ Congenital malformations - "born with" birth defects developmental problems evident at birth occur primarily during preimplantation and embryonic periods Occurrence: 1/700 live births chromosome abnormalities - genetic factors teratogens - environmental factors Preimplantation Period Overview - Period of the unattached conceptus First week of development Fertilization Preimplantation period - Fertilization - Female ovum united with the male sperm (haploid 23) = Meiosis Forms the zygote (fertilized egg) = diploid 46 Morula - solid ball of cells after initial cleavage Blastocyst (or blastula) - Travels from the site of fertilization to the uterus Implantation - end of the first week Blastula becomes embedded in the endomentrium (innermost lining of the uterus) Trophoblast layer (blastocyst) - Outside layer Gives rise to prenatal support tissues Embryoblast layer (blastocyst) - Inside of blastocyst Gives rise to the embryo Preimplantion (meiosis) developmental disturbances - Down syndrome (trisomy 21) Ectopic pregnancy: implantation of the blastocyst in the fallopian tube = not compatible with life Embryonic period - Beginning of 2nd week to the end of the 8th week Blastocyst becomes an embryo Induction (development of the embryo) - interaction between cells Proliferation (development of the embryo) - cellular growth Differentiation (development of the embryo) - change in cells to become distinct structurally and functionally Morphogenesis (development of the embryo) - development of specific tissue morphology Maturation (development of the embryo) - attainment of adult function and size Induction - Interaction between embryological cells that triggers cells to develop into specific structures Not a well understood process