Download Developmental biology (Embryology)

• Developmental biology (Embryology)
Length of pregnancy ?
- 280 days (40weeks) after the onset of last normal menstrual period
- 266 (38weeks) after fertilization
46 chromosomes (diploid), DNA
20 000 genes
meiosis: germ cells
fertilization- diploid again
gamets (haploid) : oocyte, sperms
Developmental biology (Embryology)
Early development (1.- 2. week)
importants terms: fertilization, zygote, cleavage, blastocyst,
implantation
Period of organogenesis = embryonic period (3.- 8. week)
- 3 germ layers: ectoderm, entoderm, mesoderm
- most major organs and organ systems are formed
-Size of the embryo – CRL = crown rump length (mm)
importants terms: gastrulation, neurulation, neural crest, paraaxial
mesoderm, somite, intermedial mesoderm., lateral plate mesoderm,
Fetal period - from the 9th week
-maturation and rapid growth
-Size of the fetus – CHL = crown heel length (mm)
• genetic background of development
• Genes and gene families: HOX, FGF,
FGFR, BMP, BMPR, PAX, SHH
Thomas W. Sadler, Langman's Medical Embryology, LWW
Teratology - study of abnormalities of physiological development (birth defects).
The term stems from the Greek τέρας teras (genitive τέρατος teratos), meaning 'monster' or 'marvel',
and λόγος logos, meaning 'the word' or, more loosely, 'the study of' . (http://en.wikipedia.org/wiki/Teratology )
Gastrulation – beginning of the 3rd week
Important tems: primitive streak, primitive node, epiblast, hypoblast
Invagination of epiblast
3 germ layers
Thomas W. Sadler, Langman's Medical Embryology, LWW
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1/ ECTODERM
EPIDERMIS [INCLUDING HAIR ,NAILS]
NERVOUS SYSTEM
NEURAL CREST AND ITS DERIVATIVES
2/MESODERM:
CONNECTIVE TISSUE
MUSCLES
BONES
CARDIOVASCULAR and LYMPHATIC system
UROGENITAL system
SEROUS LINING (membranes) OF BODY CAVITIES(peritoneal, pleural)
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• 3/ENDODERM :
• GUT (digestive) TUBE EPITHELIUM AND DERIVATIVES
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+ LIVER and PANCREAS
• LUNG
NEURULATION
Neural tube
Neural crest
Epidermis
Scott F. Gilbert, Developmental Biology, Sinauer
Thomas W. Sadler, Langman's Medical Embryology, LWW
Thomas W. Sadler, Langman's Medical Embryology, LWW
Defects of neurulation
anencephalus , spina bifida
Keith L. Moore, Before We Are Born: Essentials of Embryology and Birth Defects, Elsevier
MESODERM
• 1) paraxial mesoderm
• 2) intermediate mesoderm
• 3) lateral plate mesoderm
- parietal layer – body wall, serous mambranes
- visceral layer – gut, blood vessels
Thomas W. Sadler, Langman's Medical Embryology, LWW
Vessels formation
angiogenesis – vessels form from blood islands
vasculogenesis – vessels sprout from existing ones
Endoderm derivatives
Thomas W. Sadler, Langman's Medical Embryology, LWW
Pharyngeal (branchial ) arches – bars of mesenchymal tissue separated by clefts.
No.1,2,3,4-6. A lot of important head and neck structures are derivatives of them
Thomas W. Sadler, Langman's Medical Embryology, LWW
Pharyngeal arches
Somites on each
side of neural tube
(see next slide)
Human embryo (CRL 10 mm, 5th week)
Thomas W. Sadler,
Langman's Medical
Embryology, LWW
Somites - segmented series of tissue blocks on each side of neural tube
from paraxial mesoderm
Thomas W. Sadler, Langman's Medical Embryology, LWW
somite
lateral plate mesoderm somatic
neural
tube
chorda
lateral plate mesoderm splanchnic
Transverse section through somites
Thomas W. Sadler, Langman's Medical Embryology, LWW
Each somite forms:
myotome
dermatome
sclerotome
Thomas W. Sadler,
Langman's Medical
Embryology, LWW