Oral Histology & Embryology Terms PDF

**CARLOS, MEAGAN SAM C.** **DMD2C** **Oral Histology & Embryology: TERMS** 1. **Embryogenesis** -- process by which a fertilized egg develops into a fully formed organism, involving stages such as fertilization, cleavage (cell division), gastrulation, and organogenesis. 2. **Gastrulati...

**CARLOS, MEAGAN SAM C.** **DMD2C** **Oral Histology & Embryology: TERMS** 1. **Embryogenesis** -- process by which a fertilized egg develops into a fully formed organism, involving stages such as fertilization, cleavage (cell division), gastrulation, and organogenesis. 2. **Gastrulation** -- where the embryo forms three primary germ layers: ectoderm, mesoderm, & endoderm, which later develop into all body tissues and organs. 3. **Neurulation** -- process during embryonic development in which the neural plate folds to form the neural tube, which later develops into the brain and spinal cord. 4. **Amniotic Cavity** -- fluid-filled space surrounding the developing embryo, providing protection and support during development. 5. **Blastula** -- hollow ball of cells formed during early embryonic development after the morula stage, which later develops into the embryo. 6. **Cleavage** -- series of rapid cell divisions after fertilization, resulting in a cluster of cells known as the blastocyst. 7. **Ectoderm** -- outermost germ layer that forms the skin, nervous system, and sensory organs. 8. **Embryoblast** -- inner cell mass of the blastocyst that will develop into the embryo. 9. **Embryonic Disc** -- flat, bilayered structure formed from the embryoblast, giving rise to the ectoderm, mesoderm, and endoderm. 10. **Endoderm** -- innermost germ layer that forms the digestive system, lungs, and other internal organs. 11. **Epiblast** -- upper layer of the embryonic disc, which gives rise to the ectoderm and mesoderm. 12. **Fertilization** -- process in which a sperm cell and an egg cell combine to form a zygote, initiating embryonic development. 13. **Gametes** -- reproductive cells (sperm and egg) that combine during fertilization to form a zygote. 14. **Hypoblast** -- lower layer of cells in the early embryo that contributes to the formation of extraembryonic tissues. 15. **Intermediate Mesoderm** -- region of the mesoderm that gives rise to structures like the kidneys and parts of the reproductive system. 16. **Lateral Plate Mesoderm** -- part of the mesoderm that forms the heart, blood vessels, and parts of the limbs. 17. **Mesoderm** -- middle germ layer that develops into muscles, bones, the circulatory system, and more. 18. **Morula** -- ball of about 16 cells formed after the zygote undergoes several divisions; it enters the uterus around 3 days after fertilization. 19. **Neural Crest Cells** -- group of cells that migrate from the developing neural tube and give rise to a variety of structures, including peripheral nerves and facial bones. 20. **Notochord** -- rod-like structure that forms the basis for the vertebral column and signals the development of surrounding tissues. 21. **Occipital Somites** -- segmented blocks of mesoderm located near the head, contributing to the development of the muscles and vertebrae of the neck. 22. **Paraxial Mesoderm** -- mesodermal layer located alongside the neural tube, responsible for forming the somites, which give rise to muscles, bones, and skin. 23. **Primitive Node** -- cluster of cells at the anterior end of the primitive streak, involved in the formation of the notochord and patterning of the body axis. 24. **Primitive Streak** -- linear structure that forms during early development and helps establish the body's left-right and anterior-posterior axes. 25. **Trophoblast** -- outer layer of cells of the blastocyst, which helps implant the embryo into the uterine wall and forms part of the placenta. 26. **Yolk Sac** -- extraembryonic structure that provides early nourishment and is involved in blood cell formation. 27. **Blastocyst** -- fluid-filled cavity formed in the morula, separating the cells into two parts: the trophoblast and the inner cell mass. 28. **Trophoblast** -- outer layer of cells in the blastocyst that will form the placenta and support implantation into the uterine wall. 29. **Embryoblast (Inner Cell Mass)** -- group of centrally located cells in the blastocyst that will develop into the embryo. 30. **Zona Pellucida** -- glycoprotein layer surrounding the egg, which disappears when the blastocyst implants into the uterine lining. 31. **Endometrial Lining** -- lining of the uterus, where the blastocyst implants, marking the beginning of pregnancy. 32. **Stomodeum**/**Stomatodeum** -- depression in the ectoderm of an embryo between the brain and pericardium, which becomes the precursor to the mouth. 33. **Chorion** -- outermost membrane surrounding the developing embryo, which contributes to the formation of the placenta. 34. **Mandible** -- lower jawbone, crucial for the development of the face and mouth. 35. **Pharynx** -- throat region in the embryo, which gives rise to structures like the mouth and parts of the respiratory system. 36. **Groove** -- depression or indentation in a structure, in embryology, it can refer to a developmental groove where tissues or organs will form. 37. **Cheeks** -- fleshy parts of the face, located on either side of the mouth, involved in facial development. 38. **Primitive** -- early or original stages of development in an embryo, such as the primitive streak or primitive cells, from which more specialized structures arise. 39. **Pharyngeal Arches** -- tissue bands that form during early development, located beneath the brain, giving rise to structures of the head and neck, such as the jaw, ears, and throat. 40. **Branchial Arch** -- another term for pharyngeal arches, named for their similarity to gills in fish, but in humans, they form key structures in the head and neck. 41. **Cheiloschisis (Cleft lip)** -- condition where the upper or lower lip does not form properly due to the non-union of facial processes, often called hare-lip in bilateral cases. 42. **Micrognathia** -- abnormally small jaw. 43. **Macrognathia** -- abnormally large jaw. 44. **Agnathia** -- congenital absence of the upper or lower jaw. 45. **Microstomia** -- abnormally small mouth due to excessive fusion of the maxillary and mandibular processes. 46. **Astomia** -- complete closure of the mouth. 47. **Oblique Facial Cleft** -- slanted cleft extending from the mouth to the cheek, possibly reaching the lower eyelid. 48. **Aprosopus** -- condition where the face lacks features. 49. **Craniosynostosis** -- premature closure of skull sutures, affecting head shape and brain growth. 50. **Treacher Collins Syndrome** -- genetic disorder causing underdeveloped facial bones and tissues. 51. **Macrocephaly** -- abnormally large head due to brain enlargement or excess fluid. 52. **Microcephaly** -- smaller-than-normal head, usually from abnormal brain development. 53. **Staphyloschisis** -- bifid uvula, with or without cleft of the soft palate. 54. **Microstomia** -- abnormally small mouth due to excessive fusion of the maxillary and mandibular processes. 55. **Macrostomia** -- abnormally large mouth caused by incomplete fusion of the facial processes. 56. **Tuberculum Impar** -- initial medial swelling from the first pharyngeal arch that starts the formation of the tongue.