Embryology 1 PDF

 (1) (3) (2) Fertilization Fetal Embryonic (zygote) stage stage stage  (Proliferation, predifferentiation stage)  It includes of development  It begins with f...

 (1) (3) (2) Fertilization Fetal Embryonic (zygote) stage stage stage  (Proliferation, predifferentiation stage)  It includes of development  It begins with fertilization and ends with formation of bilaminar embryonic disc  The , so this stage involves: - Largely cellular proliferation - Some differentiation results from this stage because: - If injury is sever → embryo is (abortion) - If injury is less sever→  (Differentiation stage)  It extends from of development  It is characterized by of all major external and internal structures  It is because it involves many.  Thus, during this stage may develop.  (Growth stage)  It extends from of development  Development is a matter of  Embryo now is called " " take place  Develop at  Appear as on the future neck & lower head region.  There are of branchial arches formed in lateral wall of pharynx  Numbered in a cranio-caudal sequence (I,II,III,IV& VI)  The is as it disappears after short time ( )  (1) (3) (2) Development Specialization Development of of the dorsal of the mucous surface of the muscles membrane tongue  Lateral lingual swellings 1 1 Tuberculum impar Foramen cecum  Around a median elevation, the median tongue bud appears in the floor of primitive pharynx just (anterior) to (originates from 1st BA)  Two oval distal tongue buds soon develop on each side of median tongue bud (originates from 1st BA)  The two distal tongue buds rapidly increase in size, merge with each other and the median tongue bud  The fused distal tongue buds or oral part of the tongue  Line of fusion of distal tongue buds is indicated by forms identical adult derivative  Early, the developed tongue is totally to the floor of mouth  Then, tongue separates from floor of mouth by all around its periphery  Subsequently it degenerates to form  Degeneration is less extensive at the region of  Foramen cecum Copula Hypobranchial eminence elevations develop to  The first elevation (originates from 2nd BA)  The second elevation develops caudal to the copula (originates from 3rd & 4th BA)  As tongue develops, the is gradually the  So, develops from the  Terminal sulcus The line of fusion of the and parts of the tongue is indicated by called  are blocks of that are located on either side of the (give muscles) Somites Neural tube Sclerotome Dermatome (give axial (give skin) skeleton)  Most of tongue musculature is derived from the (primitive muscle cells) that migrate from  These myoblasts migrate into the tongue where they differentiate into (CN XII) is accompanies the myoblasts during their migration & innervates tongue muscles when they develop.  General sensation by [trigeminal nerve (CN V)]  Special sensation (taste) by [facial nerve (CN VII)]. While is supplied by General and special sensation by Specialized by the development of Specialized by infiltration with lymphoid tissue and development of  Tongue Anomalies Bifid tongue Microglossia fissured tongue Median rhomboid glossitis