embryo

sperm - oocyte - zygote
Blastomere- a cell
zona pellucida-cell envelope
morola-mullberry-like collection of 16+ cells ready for implantation
blastocyst-morola with cavity (blastocele) inside
blastoderm-embryonic disc (embryoblast & trophoblast)
IMPLANT - ideally on upper back wall
trophoblast- embedded in uterine endrometrium
overy progesterone production induced. Human Chorionic Gonadotropin (hCG) produced by trophoblast
d9-chorionic villi

Structures arising from the tree germ layers of gastrulaton
ENDODERM	MESODERM	ECTODERM
Respiratory tract lining Epithelium of the digestive tract, bladder, thyroid Primary tissure of the liver and pancreas	Dermis Muscles Bone, connective tissue, lymphoid tissue, Reproductive organs Cardiovascular system	Epidermis Hair, nails Lens of the eye Central and peripheral nervous system Skin & glands

TERATOGENS-

A. Embryonic Period- Conception - Week 6 From primitive foregut: Trachea bud 4 wks. enoderm lined mesoderm Trachea branch 6 wks Pulmonary Arteries perfuse developing lung tissue by following divided airways. Heart wk 3 - 2 tubes s shape develops muscle contracts wk 4 heartbeat truncus divides 6 wks &	C. Cannalicular Preiod Weeks 17-26 Aiways increase in length and diameter Airways end in blind pouches Few pulmonary Capillaries present in early period Pulmonary Capillaries proliferate rapidly towared the dend of perion Formation of alveolar ducts Appearance of Type 1 and type 2 pneumocytes- immature surfactant
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B. Pseudoglandular Period- Weeks 7-16 Branching continues to the terminal bronchi Muscle, elastic tissue and early cartilage form along the airways cilia wk 10 Goblet cells & bronchial glands wk13 Diaphragm Develops choana breaks down	D. Saccular and Alveolar Period- Weeks 27-term-post term Appearance of Alveoli Merging of the alveolar epithelium and the pulmonary capillaries Appearance of mature surfactant Alveoli continue to increase in size and number
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Heart Development
Pulm Hyper Post Natal<Fetal Circulation