embronic development for f.y
TRANSCRIPT
EMBRYONIC DEVELOPMENT
Ravi Ranjan & Gunjan MehtaDept. of Biotechnology
Spermatogenesis
Oogenesis
1st Week of Development
Fertilization
Cleavage
Blastocyst Formation
Implantation
Cleavage
Implantation of the
Blastocyst
SPONTANEOUS ABORTION (Miscarriage)
• Can occur for many reasons:• 1. Implantation did not occur (woman never knows
she’s pregnant)• 2. Not enough hCG (menses occurs)• 3. Developmental problem in fetus death in utero• 4. Not enough progesterone lining breaks down• 5. Improper implantation• 6. Improper placenta
Summary
• Cleavage is a series of mitotic divisions that results in an increase in cells, blastomeres,which become smaller with each division. After three divisions, blastomeres undergo compaction to become a tightly grouped ball of cells with inner and outer layers. Compacted blastomeres divide to forma 16-cell morula.
• As the morula enters the uterus on the third or fourth day after fertilization, a cavity begins to appear, and the blastocyst forms. The inner cell mass, which is formed at the time of compaction and will develop into the embryo proper, is at one pole of the blastocyst. The outer cell mass, which surrounds the inner cells and the blastocyst cavity, will form the trophoblast.
Summary
• The uterus at the time of implantation is in the secretory phase, and the blastocyst implants in the endometrium along the anterior or posterior wall. If fertilization does not occur, then the menstrual phase begins and the spongy and compact endometrial layers are shed. The basal layer remains to regenerate the other layers during the next cycle.
2nd Week of Development
Development of Trophoblast
Development of Bilaminar Embryonic disc
Development of Amnion
Development of Yolk sac
Development of Sinusoids
Development of Extra embryonic mesoderm
Development of Chorions
Bilaminar layer, Exocoelomic membrane & Amnion
Maternalsinusoid
Endometrium capillaries around the developing embro becomes dialted and reffered as Maternal Sinusoids.
Gastrulation
Neurulation
Development of Chorionic Villi
Development of Placenta
3rd Week of Development
3rd Week of Development
Gastrulation
Primitive Stalk formation
Primitive Node formation
Trilaminar Disk formation
Notochordal process
Notochord
Oropharangeal & Cloacal membrane
Trilaminar Disk formation
Differentiation of Primary Germ Layers (from the gastrula)
Ectoderm Mesoderm Endoderm
Nervous system Skeleton Digestive tract
Epidermis of skin Muscles, Dermis of skin
Respiratory system, Bladder
Ear, lens, cornea Circulatory system Liver, pancreas
Salivary & Pituitary gland
Gonads Epithelial lining of Cowper’s, parathyroid glands, pancreas
Caudal (posterior)
Surface Ectoderm
Hollow tube
3rd Week of Development
NeurulationEctodermal cell Notochord Neural plateMesodermal cell Notochord Vertebral bodies
Neural plate, fold, groove, tube.
Development of somitesMyotome- Skeletal muscle of neck, limbDermatome- Connective tissue, Skin dermisSclerotome- Vertebrate
Development of Intraembryonic Coelom
Development of Cardiovasular System
3rd Week of DevelopmentDevelopment of Chorionic Villi
Development of Placenta
Gestation period• During first trimester individual starts out as a zygote, then
morula, blastocyst, and after implantation, is called an embryo.• Embryonic phase of development lasts from fertilization until
the 8th week of gestation, when it becomes a fetus.• By day 35 the heart is beating, and eye and limb buds are
present.• By the end of the third month the placenta is functioning.• By month four, the rudiments of all organ systems are formed
and functioning, and from then on, fetal development is primarily a matter of growth.
Functions of the placenta:1 Transfer gasses
2 Transport nutrients
3 Excretion of wastes
4 Hormone production – temporary endocrine organ – estrogen and progesterone
5 Formation of a barrier – incomplete, nonselective – alcohol, steroids, narcotics, anesthetics, some antibiotics and some organisms can cross
Development of the Placenta
4th Week of DevelopmentOrganogenesis
Embryonic folding
Median plane- fold- Head fold, tail fold & Horizontal fold
Lateral fold- Fore gut, Mid gut, Hind gut
Otic placode- Internal Ear
Lens placode- Eyes
Pharangeal arch- Head & Neck
Embryonic Period 1st to 4th week, 5th to 8th week
Fetal Period
Human Fetus at
Ten Weeks
THANKS