Embryology 1. Embryology (the term, varieties) 2. Periods of ontogenesis 3. Germ cells 4. Stages and processes of embryogenesis 5. Extraembryonic organs (fetal membranes…) 6. Types of embryo nutrition 7. Critical (crucial) periods 8. Extracorporal fertilization

General embryology Special embryology Periods of the human life: 1. Progenesis 2. Prenatal (conceptus, embryo, fetus) 3. Postnatal Differences between germ and somatic cells Chromosomal set May fuse Dye without fusion

Biologic significance of oocyte in fertilization 1 Biologic significance of oocyte in fertilization 1. Give half of a necessary amount of chromosomes 2. Supply the nutrition of embryo 3. Protection of embryo at the early stages of development Biologic significance of spermatozoa in the fertilization 1. Active passage forward to the ovum 2. They give 23 “father” chromosomes 3. Sex of embryo depends on spermatozoon type 4. Give the centriole 5. Mitochondrial DNA 6. Introduce special cleavage signal protein 7. Stimuli oocyte meiosis

Stages and processes of embryogenesis Result Place and time Fertilization Zygote Uterine tube ampula (1st day) Cleavage Blastula Uterine tube (2-4th days) and uterine cavity (5-7th days) Gastrulation Gastrula Endometrium (7-14th days) Neurulation Neurula Endometrium (14th -17th days) Histogenesis Tissues Organogenesis Organs Systemogenesis System of organs

Corona radiata cells Stage 1 Stage 2 Polar body division Penetration Acrosome Meiotic division of secondary oocyte Nucleus Cell membrane Fusion of oocyte and spermatozoon membranes Stage 3

Zygote formation Zona Corona pellucida radiata Penetration Male pronucleus Female pronucleus Centrosome Metaphase plate Meiotic division

Synkarion, two blastomeres

Cleavage (full subequal asynchronic )

Morula

Blastocyst Embryoblast Blastocyst cavity Trophoblast

Implantation Endometrial epithelium Endometrial stroma Trophoblast cells Blastocyst cavity Embryoblast

Implantation

Gastrulation appearance and development of germ layers Peculiarities of the human embryo gastrulation 1. Full subequal asynchronic cleavage – blastocyst 2. Forestall development of extraembryonic organs 3. Embryo implantation into endometrium and placenta formation 4. All (three) germ layers are forming from primary ectoderm

Late gastrulation 14th 17th days Early gastrulation 7th -14th days 1. Embryoblast delaminates into epiblast and hypoblast 2. Amnion originate from epiblast (primary ectoderm) 3. Yolk sac – from hypoblast (primary endoderm) 4. Trophoblast differentiates into cytotrophoblast and syncytiotrophoblast 5. Embryonic disc – the attachment of amniotic vesicle bottom and the roof of yolk sac 6. Embryo’s body has one layer – the amniotic vesicle bottom/ Late gastrulation 14th 17th days 1. Migration with primitive streak formation 2. Extraembryonic mesoderm migrate from embryonic disc 3. Three layers of embryo body are formed at the same time from embryonic ectoderm

EXTRAEMBRYONIC ORGANS 1. Amnion 2. Yolk sac 3. Umbilical cord 4. Allantois 5. Chorion 6. Placenta

Vitelotrophic – 30 hours, yolk inclusions Histiotrophic – 2nd day –3rd month Hematotrophic– 3rd month …

Human placenta II discoidal hemochorial Umbilical cord Fetal placenta Maternal plac. Cotyledon Amnion Vessels

CRITICAL (crucial) PERIODS 1944 Norman Gregg (austral) 1960 P Svetlow (rus) 1. Progenesis or gametogenesis 2. Fertilization 3. Implantation 4. Placentation 5. Growth of the brain 6. Organo- and systemogenesis 7. The birth 8. Neonatal period and first year of life 9. Pubertation 10. Menopause

EXTRACORPORAL FERTILIZATION 1976 Luisa Brown (GB) Edvards and Stantow 1. Special surgical manipulation 2. Fertilization “in vitro” 3. Incubation for 3-4 days (cleavage) 4. Blastocyst (18-32 blastomeres) – “free blastocyst” in uterus 5. Implantation begins (15 % successful)