1. 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

2. 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

3. Types of oocytes Human oocyte – oligolecytal II isolecytal
Yolk inclusions
Alecytal
Olygolecytal
Polilecytal
Nucleus location
Primary
Secondary

6. Spermatozoa A lot of … Constantly Motile Types Androspermium 22+y
Gynecospermium 22+x

8. Biologic significance of oocyte in fertilization 1
Biologic significance of oocyte in fertilization 1. Gives half of a necessary amount of chromosomes 2. Supplies the nutrition of embryo 3. Protection of embryo at the early stages of development
Biologic significance of spermatozoon in the fertilization
1. Active passage forward to the ovum
2. Gives 23 “father’s” chromosomes
3. Sex of embryo depends on spermatozoon type
4. Gives the centriole
5. Mitochondrial DNA
6. Introduces special cleavage signal protein
7. Stimulies oocyte meiosis

9. 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
Systems of organs

11. Fertilization The biological significances of fertilization:
1. The restoration of karyotype.
2. Determination of the embryo sex.
3. Initiation of a cleavage.
Distant stage
Contact stage

12. Distant stage 1. Capacitation– special activation of spermatozoa .
2. Taxis –active movement of spermatozoa.
A. Chemotaxis (chemo tropism).
B. Rheotaxis.
C. Stigmotaxis.

13. Contact stage 1. Acrosomal reaction – exfusion of acrosomal enzymes.
2. Denudation – dispersion of the corona radiate.
3. Penetration of zona pellucida.
4. Cortical reaction – passage of the oocyte cortical granules content outside.
Tunica of fertilization + perivitelin space

14. 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

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

17. Synkarion, two blastomeres

18. Cleavage (full subequal asynchronic )

19. Morula

20. Blastocyst
Embryoblast
Blastocyst
cavity
Trophoblast

21. Implantation 1. Blastocyst inculcation into the endometrium.
2. Phases of implantation: adhesion and invasion.
3. Duration - 40 hours.
4. Normal site – in the uterine body.
Abnormal implantation sites (ectopic pregnancy)

22. Implantation adhesion
Endometrial
epithelium
Endometrial
stroma
Trophoblast
Trophoblast
cells
Blastocyst
cavity
Embryoblast

23. 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

24. Implantation invasion

25. Late gastrulation 14th 17th days
Early gastrulation th -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 th 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

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

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

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

29. 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

30. 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)