1-Fertilization, stages of the intrauterine growth of fetus, development of mother and fetal parts of membrane. Placenta, its anatomy and function.pptx

Gynaecology

1. Fertilization, stages of the intrauterine growth of fetus, development of mother and fetal parts of membrane. Placenta, its anatomy and function Ganeeva Albina V. Teaching and research assistant of the department of obstetrics and gynecology

2. Introduction Pregnancy , also known as gestation , is the time during which one or more offspring develops inside a woman. Pregnancy usually occurs by  sexual intercourse , but can occur through  assisted reproductive technology   procedures . A pregnancy may end in a live birth , a spontaneous miscarriage , an induced abortion , or a stillbirth .

3. Introduction Pregnancy is divided into three trimesters . The first trimester – 0 – 13 weeks The second trimester – 14 – 27 weeks The third trimester – 28 w - until childbirth https://en.wikipedia.org/

4. So from what does it all start?

5. Menstrual cycle Menstrual cycle is a complex of cyclic functional processes in the female genital system that takes place each month. It starts from the 1 st day of menstruation and finishes when the next m enstruation starts . Physiologic menstrual cycle includes 2 main processes : the growth and maturation of follicle ; Changes in endometrium for implantation of the fertilized egg . Every normal menstrual cycle is a preparation of the female organism to pregnancy. Menstruation is a periodic bleeding from the uterus. Menstruation is a component of menstrual cycle. Menstrual discharge consist of the mixture of endometrium, fragments and different amounts of liquid, sometimes with clots, blood .

6. Levels of regulation of menstrual function Highest levels: Cortex and limbic system hypothalamus Pituitary gland Lower levels: ovaries u terus and other target tissues: (mammary glands, vagina, hair follicles, skin, bones, adipose tissue)

7. The first level of regulation Hormonal system ‘s management of reproductive function begins with the level of specialized neurons in the brain ( suprahypothalamic structures ). They receive information about the state of the external environment, convert it into neurohumoral signals, which through a neurotransmitter connection enter the secretory cells of the hypothalamus. Among the neurotransmitters the key role play: dophamine , norepinephrine and serotonin , opioid peptides, endorphins and enkephalins . neurotransmitters The 1 st level The target (the 2 nd level)

8. The second level of regulation i s hypophysotrophic zone of hypothalamus : ventrolateral, dorsomedial and arch-shaped nuclei where gonadotrophic releasing-hormones are produced (GTRH). 2 main variants of GTRH are known: stimulating – liberins (they stimulate excretion of hormones by adenohypophysis), inhibitory – statins (they inhibite excretion of hormones by adenohypophysis). Gonadoliberines enter the blood in a pulsating circhoral mode: 1 pulsation in 60 - 90 minutes. GTRH

9. The third level of regulation is presented with the influence of the anterior part of pituitary body ( adenohypophysis ). Adenohypophysis produces gonadotropic hormones : folliculstimulating hormon (FSH), luteinizing hormone (LH), prolactin and others.

10. FSH: stimulates the growth of the follicle, stimulates the proliferation of granulosa cells (that produce estrogens), produces the formation of LH receptors on the surface of granulosa cells. FSH, LH The 3 rd level of regulation The target (the 4th level of regulation) LH : stimulates ovulation stimulates the formation of the corpus luteum and, together with prolactin, promotes secretion of progesterone in the granulosa-lutein cells .

11. The fourth level of regulation is depicted by the ovaries . The cyclic changes in the ovaries are called ovarian cycle . They distinguish two phases of the ovarian cycle, they are: the follicular phase – maturation of a dominant follicle the lutein phase when an endocrine gland - the corpus luteum is forming.

12. From the 1 st day of menstrual cycle one follicle (rarely two ) develops the following stages: primordial — primary — secondary — tertiary (Graafian vesicle). FSH stimulates this process.

13. The 5 th level of regulation is presented by endometrium. The cyclic changes in uterus are called uterine cycle . They distinguish 3 phases of the uterine cycle, they are: Desquamation (Menstruation) Proliferative phase Secretory phase

14. Ovum An ovum (Latin: "egg", plural: ova) is the name for the haploid female reproductive cell, or gamete. The ovum contains the X sex chromosome. The ovum is surrounded by three coats: • yolk memb rane which is the superfi cial layer of the ovum cytoplasm; • a thick luminous coat of the follicular epithelium, zona pellucida ; • radiate crown ( corona radiata ) — granulosa cells placed in a radial fashion in 2–3 layers; they adhere to the ovum immediately. https://picgalleria.com/

15. Fertilization The process of union of a haploid male gamete or sperm with a haploid female gamete or ovum to form a diploid cell, the zygote, is called fertilization . oocyte ovulation and release with associated cells, from ovary into fimbria then into uterine tube (oviduct, uterine horn, fallopian tube) and epithelial cilia mediated movement. spermatozoa ejaculation, deposited in vagina, movement of tail to "swim" in uterine secretions through cervix, uterine body and into uterine tube, have approximately 24-72h to fertilize oocyte. Fertilization takes place usually in the ampulla of the fallopian tube.

16. Fertilization Fertilization takes place usually in the ampulla of the fallopian tube. Fertilization can also occur outside oviduct, associated with In Vitro Fertilization (IVF, GIFT, ZIFT...) and ectopic pregnancy The majority of fertilized eggs do not go on to form an embryo

17. Fertilization Events of Fertilization: 1. Activation of sperm and ovum: The sperms can fertilize an ovum only they are able to secrete the chemical hyaluronidase and possess a surface protein called antifertilizin (composed of acidic amino acid). The ovum secretes a chemical named fertilizin (composed of glycoprotein = mono saccharides + amino acids). It mixes with the water to form egg water which attracts the sperms of its own species.

18. Fertilization 2. Penetration of sperm: The fertilizin of an egg interacts with the anti fertilizin of sperm of the same species. This attraction between fertilizin and antifertilizin makes the sperms stick to the egg surface. The process of acquiring the capacity to fertilize the egg by the sperm is called capacitation. In this process, the membrane surrounding the acrosome of the sperm breaks and releases its contents, the sperm lysin . S perm lysin dissolves zona pellucida as a result of which the sperm reaches the plasma membrane of the egg. The above changes on the sperm head are called acrosome reaction . Once one sperm has entered the egg (ovum) the vitelline membrane thickens and is converted into fertilization membrane. This membrane is rigid and never allows other sperms to pass through this membrane.

19. Fertilization 3. Amphimixis : Mixing up of the chromosomes of a sperm and an ovum resulting in a diploid zygote nucleus is known as amphimixis or karyogamy . The mother is now said to be pregnant. The centrosome form asters and spindle fibres . The paternal and maternal chromosomes move to lie in the equator of the spindle and the zygote is ready for division by cleavage. https://www.pinterest.co.uk/pin/125749014571735735/

20. Post-fertilization Events The first cleavage of fertilized egg takes place over 24 hours, others — every 12 hours. For three days the morula persists in the uterine tube. For 4 days, as the outer layer of blastomeres grows thicker, an inner cavity, blastocoel, forms in the morula. This is the way the blastocyst , or the third presomite stage, develops. The superficial light cells of the blastocyst give rise to an external thin layer thus forming the primary trophoblast while the dark cells give rise to the embryoblas t. The primary trophoblast is a stem cell for most placental cells and tissues; the embryoblast is a source of all fetal cells, tissues and related membranes.

21. Post-fertilization Events

22. Implantation From day 6–7, once the blastocyst hatches out of the partially dissolved zona pellucida , its implantation ( nidation , from Latin nidus, nest) takes place. Implantation proceeds in two stages: adhesion and invasion . First the trophoblast adheres to the endometrium and starts differentiating into cytotrophoblast still connected to the embryo wall, and syncytiotrophoblast , a peripheral layer in the form of cytoplasm mass. Implantation can only occur during the implantation window , a period of time limited to day 19-22 of the period when the endometrium is sensitive to the blastocyst to the utmost.

23. Stages of the intrauterine growth of fetus • Embryonic stage starting at the moment of fertilization (at two weeks of pregnancy)1 to full 10 weeks of pregnancy (full 8 weeks after fertilization) sees the following events: – 3–8 weeks: formation of rudiment organs in the fetus; – 2–4 weeks: formation of the heart and vessels; – 4–5 weeks: beginning of lung formation, early development of the nervous system; – 7–8 weeks: kidney formation. • Fetal (syn.: antenatal) stage lasting from 11th-week of pregnancy until birth (8–38 full weeks from fertilization or 10–40 weeks from the fi rst day of the last menstrual period): – 8–12 weeks: sex differentiation; – 15–20 weeks: intensive growth and maturation of the cerebral cortex; – 20–24 weeks: formation of major functional systems of the fetus.

24. Fetal Membranes and Placenta

25. Placenta Placenta, or the child’s place, is an extremely important organ, which connects the functional systems of the mother and fetus .

26. At the end of pregnancy the placenta weighs 500– 600 g, diameter — 15–18 cm, thickness — 2–3 cm. There are maternal (turned to the uterine wall) and fetal (turned to the amnion’s cavity) surfaces in the placenta .

27. C otyledon is the structural unit of placenta. It is formed by the stem villus and its branches (anchor, liber and ending villi). The mature placenta has 40–70 parts (cotyledons). In each part anchor chorial villi are washed by the maternal blood , which circulates in the intervillous lacuna .

28. Placenta accomplish a great number of functions The respiratory function is in the transport by the simple diffusion of oxygen from the mother to the fetus and discharge of the carbon oxide in the reverse direction . The function of the nutrition and excretion of the products of metabolism . transport, accumulation and excretory functions as to the majority of the electrolytes, including important macro- and microelements ( ferrum , cuprum, zinc, manganese, cobalt, etc.). Hormonal function of the placenta consists in the synthesis, secretion and transforming of the protein and steroid hormones in syncytiotrophoblast .

29. the function of immunobiological protection of the fetus . It is an immune barrier, which separates two genetically heterologous organisms (mother’s and fetal), preventing the development of the immune conflict. The barrier function of the placenta consists in the protection of the organism of the fetus from the injury factors of the environment (microorganisms, chemical factors, medicines, etc.), but in some cases it is insufficient. Placenta accomplish a great number of functions

30. Umbilical cord

31. Thank you!