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Development of the Vertebrate Body Plan. Temple University School of Medicine. Thomas A. Marino, Ph.D. Department of Anatomy and Cell Biology. DEVELOPMENT OF THE VERTEBRATE BODY PLAN. Early Development 1. Development of Ectoderm A. Neural Tube B. Surface Ectoderm
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Development of the Vertebrate Body Plan Temple University School of Medicine Thomas A. Marino, Ph.D. Department of Anatomy and Cell Biology.
DEVELOPMENT OF THE VERTEBRATE BODY PLAN Early Development 1. Development of Ectoderm A. Neural Tube B. Surface Ectoderm 2. Development of Endoderm A. G.I. Tract B. Respiratory Tree C. Pharynx 3. Development of Mesoderm A. Paraxial B. Intermediate C. Lateral
Gastrulation Ectoderm Amniotic Cavity Paraxial mesoderm Intermediate mesoderm Lateral plate mesoderm Yolk Sac Notochord Endoderm
Mesoderm Blood Islands
Mesoderm Three sites of early blood island formation: • cardiogenic area • yolk sac • chorion and connecting stalk
Mesoderm Foregut Dorsal Aorta Heart Body Cavity Amniotic Cavity
Gastrulation Ectoderm Amniotic Cavity Paraxial mesoderm Intermediate mesoderm Lateral plate mesoderm Yolk Sac Notochord Endoderm
Somite (Paraxial Mesoderm) Lateral plate mesoderm Intermediate Mesoderm
Dermamyotome Somite Sclerotome
Dermomyotome WNT PAX3 Scleretome (PAX1) SHH
Neurotrophin 3(NT-3) Back (epaxial) muscles Dermis NT-3 WNT Body wall and Extremity Muscles MYF5 MYOD WNT
Muscles, skeleton except skull dermis of skin connective tissue Mesoderm urogenital system including gonads, ducts, and accessory glands Paraxial Mesoderm Lateral Mesoderm Intermediate Mesoderm connective tissue of viscera and limbs serous membranes of pleura, pericardium and peritoneum blood and lymph cells cardiovascular and lymphatic systems
Homeobox genes &Anteroposterior Axis formation Back Tail Head 3’ 5’ HOX-A HOX-B HOX-C HOX-D Retinoic Acid
Timing of pregnancy • Ovarian follicle matures • Ovulation • Fertilization • Blastocyst • Bilaminar Embryonic Disc • Gastrulation begins • Beginning of last menstrual period • Proliferative phase of menstrual cycle • Secretory phase of menstrual cycle. • Implantation • Primary villi in placenta • First menstrual period missed • Day 0 • Day 1 • Day 6 - 7 • Day 14 • Day 15
Timing of pregnancy Embryology/ Gestational Age Clinical Age
Pregnancy loss • Approximately 30% of the fertilized eggs are carried successfully. • Of the 70% that are unsuccessful almost 1/3 are lost prior to implantation. • About 40% of postimplantation pregnancies abort spontaneously, • Clinically only 10 - 15% are observed.
Pregnancy loss • Studies on aborted material demonstrates 50 - 60% have chromosomal anomalies. • Very early losses closer to 70% • Higher spontaneous loss in older women. • Other reasons for loss: • Genital tract abnormalities. • Infections • Endocrine and metabolic anomalies • Hematologic and immune disorders
In one month In six months In one year Early 20's 25% 75% 94% Late20's/early30's 15% 38-47% 70-85% Late30's 10% 22-24% 65-70% Chances of Conception* * from iVillageHealth.com.
No. of months Early 20's 4-5 Late 20's 5-7 Early 30's 7-10 Late 30's 10-12 Average Time to Conception* * from iVillageHealth.com.
Confirmation of Pregnancy. • Human Chorionic Gonadotropin (hCG) produced by the syncytiotrophoblast cells. • hCG maintains the corpus leuteum for production of progesterone • hCG can be detected by day 14 of pregnancy or 28 days LMP • As soon as lacunae are formed and communicate with maternal blood hCG is detected.