Transcript No Slide Title

Brad Martinsen, Ph.D.
Department of Pediatrics
Pediatric Cardiology
Human Embryology
Week 1: Fertilization to Implantation
Week 2: The Bilaminar Embryo
Week 3: The Trilaminar Embryo
Neurulation and Neural Crest
Musculoskeletal System
Head & Neck (brief introduction)
Eye and Ear Development
Heart
Foregut/Midgut/Hindgut
Renal System
Reproductive System
1. Reading assignments for first exam:
Human Embryology, Larsen, 3rd & 2nd ed.
Larson pp1-67 (1-63)
Larson pp 80-93, 98-102 (73-87, 92-96)
Larson pp 315-335 (311-329)
2. Exam #1-->
Handouts are a complete review of the
reading and what I will say in lecture.
Use reading assignments to clarify anything said in
lecture or in the handout. Not all detail in the
reading assignments will be on the exam.
Fertilization
First Days of Development
Day 0-5
Compaction
starts
First Days of Development
Day 6
Review Question.
Which of the following is the
origin of the mitochondrial DNA
of all human Adult Cells?
A) Paternal only
B) Maternal only
C) A combination of paternal and maternal
D) Either paternal or maternal
E) Unknown origin
Review Question.
Which of the following is the
origin of the mitochondrial DNA
of all human Adult Cells?
A) Paternal only
B) Maternal only
C) A combination of paternal and maternal
D) Either paternal or maternal
E) Unknown origin
First Days of Development
Day 7
Week Two
Days 8
Day 9
Day 10
Day 11
Day 12
Days 12-13
Chorion membrane
consists of?
Days 13
Day 14-15
Primary ectoderm:
primordial germ cells,
endothelial cells, and
hematopoietic stem cells.
Extraembryonic mesoderm
of the yolk sac wall is a
major site of hematopoiesis.
Chorion membrane
consists of?
Origin of the germ line
A. Migration of the primordial germ cells.
B. Migration into posterior body wall.
2 Weeks
->ovarian follicle cells
4-6 weeks
10th
Thoracic
Vertebrae
->Sertoli cells
Teratoma:
Clinical Application
Human chorionic gonadotropin (hCG)
•hCG is a 57,000 MW glycoprotein with two subunits
(alpha and beta) produced by the syncytiotrophoblast.
•Enters the maternal blood circulation.
•Prevents degeneration of the corpus luteum.
•Stimulates production of progesterone in the corpus luteum
and chorion, which sustains the placenta.
•Can be assayed in maternal blood at day 8 after fertilization
And in maternal urine at day 10. This is the basis of
early diagnosis of pregnancy.
Clinical Application
Complete hydatidiform mole
Persistent trophoblastic disease
Metastatic choriocarcinoma
IV. Clinical Applications.
F. Genomic Imprinting.
1. Cytogenetic analysis of hydatidiform moles suggests
Paternal genetic complement->placental development.
Maternal genetic complement->embryo development.
2. Methylation of DNA is a mechanism that leads to independent
expression of maternal and paternal genomes during
early development. Female germ line highly methylated.
3. Example of pattern of inheritance:
Father->Prader-Willi Syndrome
Mother->Angelman Syndrome
4. Severity and age of onset of several genetic diseases also differ
on inheritance pattern.
Week Three.
I. Gastrulation and somite/Nt
development.
A. Primitive Streak.
I. Gastrulation and somite/Nt
development.
B. Process of Gastrulation.
I. Gastrulation and somite/Nt
development.
B. Process of Gastrulation.
I. Gastrulation and somite/Nt
development.
B. Process of Gastrulation.
I. Gastrulation and somite/Nt
development.
B. Process of Gastrulation.
I. Gastrulation and somite/Nt
development.
C. Paraxial, intermediate, and lateral plate mesoderm.
Axial skel.
Vol muscl.
Dermis
Splanchnopleuric
Somatopleuric
mesoderm
Urinary system
Genital system
I. Gastrulation and somite/Nt
development.
C. Paraxial, intermediate, and lateral plate mesoderm.
I. Gastrulation and somite/Nt
development.
D. Induction of the neural plate.
I. Gastrulation and somite/Nt
development.
D. Induction of the neural plate.
Id2 gene
expression
I. Gastrulation and somite/Nt
development.
D. Induction of the neural plate.
I. Gastrulation and somite/Nt
development.
D. Induction of the neural plate.
Cranial
Vagal
Trunk
Lumbosacral
I. Gastrulation and somite/Nt
development. E. Clinical Applications.
-->Neural crest cells that give rise to Odontoblasts stop
migrating and settle down against the buccal epithelium
at locations of the future teeth.
--> Teeth are composite structures made up of the
outer white enamal which covers the teeth above the gums
and the inner dentin, a different mineralized tissue forming
the root and interior of the teeth.
--> Dentin and enamel are extracellular products of two
different types of cells, the ameloblasts (enamel) and
odontoblasts (dentin).
I. Gastrulation and somite/Nt
development.
E. Clinical Applications.
Rieger Syndrome:
-->Embryological disturbance of the neural crest ectoderm
results in severe enamel hypoplasia, conical and misshapen
teeth, hypodontia, hyperdonita, and impactions. Abnormalities
of migration along the buccal epithelium results in ectopism.
Gastrulation and somite/Nt
development
Paraxial, intermediate, and lateral plate mesoderm
Axial skel.
Vol muscl.
Dermis
Splanchnopleuric
Somatopleuric
mesoderm
Urinary system
Genital system
Form ~44 pairs of somites then
caudal most 7 somites disapear
giving rise to 37 pairs.
1-4 somites: occipital part of the
skull, bones of nose and eyes, &
muscles of the tongue.
Next 8 pairs: form in the
presumptive cervical region. Give
rise to occipital bone and cervical
vertebrae, and assoc. muscles.
Next 12 pairs: Thoracic somites-->
thoracic vertebrae, and associated
muscles.
5 lumbar somites, 5 sacral somites,
&
Finally 3 coccygeal somites.
Musculoskeletal System
Role of somites…
Somites subdivide into three kinds
of mesodermal primordium.
Dermatome
Myotome
Day 22
Day 28
Day 31
Vertebral Column
5-7 weeks
Adult >25yrs
Vertebral Column
Intersegmental position of the vertebrae
Day 31
How do the spinal nerves escape from the developing vertebral canal?
Why do 8 cervical sclerotomes produce 7 cervical vertebrae?
Vertebral Column
Intervertebral disk: Consists
of the:
nucleus pulposus (remnant of
the notochord) and
annulus fibrosus (outer rim
of fibro-cartilage, derived
from mesoderm/sclerotome).
Skeletal Muscle
Trunk musculature
Back Muscles
Intercostal &
Abdominal muscles
Limb Skeleton and Musculature
development
Somites induce somatopleuric plate to form the limb buds.
Day 24: the upper limb bud appears in the
lower cervical region.
Day 28: the lower limb bud appears in the
lower lumbar region.
AER
Somite, lateral plate mesoderm, and
neural crest contribution to the limb
Bone, tendons, ligaments
Somites->musculature of the limb
N.C. forms the
Melanocytes & Schwann
Cells.
Limb Musculature development
Cervical and thoracic somite cells invade the
upper limb bud to form the limb
musclulature.
Lumbar somite cells invade the lower limb
buds to form the leg musculature.
Dorsal (Posterior) Muscle Mass:
Upper limb-->extensors and supinators
Lower limb-->extensors and abductors
Ventral (Anterior) Muscle Mass:
Upper limb-->flexors and pronators
Lower limb-->flexors and adductors
Rotation of the limbs
Note that the upper limbs rotate laterally 90 degrees, whereas the
lower limbs rotate medially 90 degrees, which sets up the following
anatomic situations:
1.
Flexor compartment of the upper limb is anterior, whereas the
flexor compartment of lower limb is posterior.
2.
Extensor compartment of upper limb is posterior, whereas the
extensor compartment of lower limb is anterior.