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Theme: Up-to-date perspectives of regeneration and transplantation. Biological mechanisms of homeostasis maintenance Lecturer : prof. Fefonyuk L.Ya. Slide 2 Reproduction is the method by which individuals give rise to other individuals of same type. There are two types of reproduction : There are two types of reproduction : asexual and sexual asexual and sexual Slide 3 Types of reproduction asexualsexual Organisms Organisms single-cellular organisms, multi-cellular organisms: one ore more somatic cells of parental organisms; Parental organisms forms gametes Parents Parents One person Two persons Offspring's Offspring's genetically identical to its parent like a xero copy. genetically different from parents Cell formation Cell formationMitosisMeiosis Slide 4 Forms of asexual reproduction in single-cellular organisms: Asexual is a reproduction without the fusion of sexual cells, identical offspring grows directly from a one or few body cells, which divides mitotically Asexual is a reproduction without the fusion of sexual cells, identical offspring grows directly from a one or few body cells, which divides mitotically binary fission parent binary fission parent cell splits in two cells by mitosis cell splits in two cells by mitosis Slide 5 Asexual reproduction endogony - in parent cell forms only two daughter cells by internal budding endogony - in parent cell forms only two daughter cells by internal budding schizogony - formation a great amount of daughter cells in parent cell schizogony - formation a great amount of daughter cells in parent cell Slide 6 Asexual reproduction budding - after karyokinesis the special region in parent cell rapid grows and organized into new organism. budding - after karyokinesis the special region in parent cell rapid grows and organized into new organism. sporogony - is reproduction by the spores sporogony - is reproduction by the spores Slide 7 Forms of asexual reproduction in multi-cellular organisms vegetative (regeneration) a group of cells from the parent organism separates and new organism forms vegetative (regeneration) a group of cells from the parent organism separates and new organism forms Slide 8 Asexual reproduction polyembriony - the production of two or more embryo's from the one zygote polyembriony - the production of two or more embryo's from the one zygote sporogony - is reproduction by the spores sporogony - is reproduction by the spores Slide 9 Sexual - is a reproduction by fusion of sexual cells and formation of zygote In sexual reproduction, genetic material from two individuals combines to begin the life of a third individual who has a new combination of inherited traits In sexual reproduction, genetic material from two individuals combines to begin the life of a third individual who has a new combination of inherited traits Slide 10 Sexual reproduction Forms of sexual reproduction in single-cellular organisms are Conjugation a cytoplasm bridge forms between two organisms, the nuclei transfer across this bridge and after exchange ones forms a new gene combination but no new offspring. Conjugation a cytoplasm bridge forms between two organisms, the nuclei transfer across this bridge and after exchange ones forms a new gene combination but no new offspring. Copulation - two individuals acquire the gametes properties, fuse and form a zygote the life of a new individual begins. Copulation - two individuals acquire the gametes properties, fuse and form a zygote the life of a new individual begins. Slide 11 In multicellular organism sexual reproduction may be two forms: - with fertilization - without fertilization Parthenogenesis is the development of new organism from an egg without fertilization. Parthenogenesis is the development of new organism from an egg without fertilization. Slide 12 Ontogenesis Ontogenesis the development of the individual organism. the development of the individual organism. It includes the set of morphological, phisiological and biochenical transformations from the moment of germing up to death. It includes the set of morphological, phisiological and biochenical transformations from the moment of germing up to death. Slide 13 Types of ontogenesis in animals: Types of ontogenesis in animals: 1. The larval type of an ontogenesis is characterized by development of an organism by metamorphosis. Metamorphosis is change of shape or structure of an organism from one developmental stage to another. F/e mosquito: ovum- larva- pupa - imago; F/e mosquito: ovum- larva- pupa - imago; louses ovum- larva - imago; louses ovum- larva - imago; pincers ovum- larva- nymph - imago. 2. The non-larval type of an ontogenesis is characterized by formation of an organism in an egg (birds) an egg (birds) 3. Intrauterine ontogenesis is development of an organism inside a maternal organism. (mammalian). Slide 14 The ontogenesis of multicellular organisms is divided in two periods 1 embryonic 2 postembryonic. For higher animals and man there are: For higher animals and man there are: 1) prenatal (before birth) 2) posnatal (after birth) periods of development Slide 15 Germ cells The ovum nourishes the embryo with yolk, which contains rich stores of lipids. The ovum nourishes the embryo with yolk, which contains rich stores of lipids. It provides the machinery for protein synthesis It provides the machinery for protein synthesis Slide 16 An ovum is enormous in size. It protects the developing embryo inside jellylike protein coatings and strong membranes (zona pellucida), sacs of fluid, and sometimes hard or leathery shells. An ovum is enormous in size. It protects the developing embryo inside jellylike protein coatings and strong membranes (zona pellucida), sacs of fluid, and sometimes hard or leathery shells. Corona radiata outside the cell consists of the great amount of follicular cells, which produce follicular fluid for attracting the sperms. Corona radiata outside the cell consists of the great amount of follicular cells, which produce follicular fluid for attracting the sperms. Slide 17 Distinguish the following types of ovum cells: Distinguish the following types of ovum cells: The isolecythal ovum contain a little yolk. It is distributed in regular intervals on all cytoplasm of an ovum. The isolecythal ovum contain a little yolk. It is distributed in regular intervals on all cytoplasm of an ovum. (ovum of mollusca, lancelet, mammalian). (ovum of mollusca, lancelet, mammalian). The telolecythal ovum have much yolk of grains. They collect at a vegetative pole. On animal pole there is cytoplasm without yolk and with nucleus.(ovum of fishes, amphibians, reptilie). The telolecythal ovum have much yolk of grains. They collect at a vegetative pole. On animal pole there is cytoplasm without yolk and with nucleus.(ovum of fishes, amphibians, reptilie). The centrolecythal ovum has the central nucleus and around it settles down yolk as grains. (insects). The centrolecythal ovum has the central nucleus and around it settles down yolk as grains. (insects). Slide 18 Slide 19 Unlike the egg, the sperm is one of the smallest cells in the body. Unlike the egg, the sperm is one of the smallest cells in the body. Each sperm consists of: Each sperm consists of: a head region a head region a body or midpiece a body or midpiece a tail or flagellum. a tail or flagellum. The head has a haploid nucleus. An acrosome a small bump on the front end of the head contains enzymes that help the cell penetrate the ovums outer membrane. Slide 20 Sperm cell The body or midpiece has mitochondria to provide the cell energy and centrioles. The body or midpiece has mitochondria to provide the cell energy and centrioles. A tail consists of microtubules for propulsion. A tail consists of microtubules for propulsion. The sperms streamlined size and shape effect its narrow objective: to reach the egg, penetrate its coating, and deliver a haploid nucleus into the eggs cytoplasm The sperms streamlined size and shape effect its narrow objective: to reach the egg, penetrate its coating, and deliver a haploid nucleus into the eggs cytoplasm Slide 21 Oogenesis This process begins in a haploid oogonium. This process begins in a haploid oogonium. An oogonium accumulates cytoplasm, replicates its chromosomes- primary oocyte. An oogonium accumulates cytoplasm, replicates its chromosomes- primary oocyte. In meiosis I, the primary oocyte divides to form a small polar body and a large, haploid secondary oocyte. In meiosis I, the primary oocyte divides to form a small polar body and a large, haploid secondary oocyte. Slide 22 Oogenesis Ovulation dischange (going out) of a secondary oocyte from a follicule of the ovary. Ovulation dischange (going out) of a secondary oocyte from a follicule of the ovary. In meiosis II, the secondary oocyte divides to yield another small polar body and a mature ovum. Therefore, each cell undergoing meiosis in female can potentially divide to yield a maximum of four cells, only one of which will become the ovum In meiosis II, the secondary oocyte divides to yield another small polar body and a mature ovum. Therefore, each cell undergoing meiosis in female can potentially divide to yield a maximum of four cells, only one of which will become the ovum Slide 23 Spermatogenesis Sperm development begins with spermatogonia. Sperm development begins with spermatogonia. A diploid spermatogonium divides mitotically and becomes a primary spermatocyte as it moves toward the lumen of the tubule. A diploid spermatogonium divides mitotically and becomes a primary spermatocyte as it moves toward the lumen of the tubule. In meiosis I- to form two secondary spermatocytes. In meiosis I- to form two secondary spermatocytes. In meiosis II, each secondary spermatocyte divides to yield two equal sized spermatids. In meiosis II, each secondary spermatocyte divides to yield two equal sized spermatids. Therefore, each cell undergoing meiosis in male can potentially divide to yield a maximum of four spermatids. Therefore, each cell undergoing meiosis in male can potentially divide to yield a maximum of four spermatids. Slide 24 GametogenesisPeriodsSpermatogenesisOogenesis Cells Genetic formula Cells Reproduction Cells divides mitoticaly - from puberty to death - strongly at 3-7 m. in embryogeny completed at 3-d year spermatog onia 2n2c 2n4c oogonia2n2c2n4c Slide 25 Cells Genetic formula Cells Growth Cell growth and increase in size. Duplication of DNA. primary spermatoc yte 2n4c primary oocyte 2n4c Slide 26 Cells Genetic formula Cells Maturation Meiosis I- cells halves genetically material Meiosis II two secondary spermatocyt es two spermatids 1n2c1n1cSecondaryOocyte mature ovum 1n2c1n1c Slide 27 Cells Genetic formula Cells Formation (spematogenesis) Spiralization of chromosome s, formation of acrosome,cel l centre, tail sperms1n1c Slide 28 Gametogenesis Slide 29 Ontogenesis abnormalities 1) multynuclear oocytes; 2) 10% ofcan be abnormal; 3) development of germ cells with 22 or 24 chromosomes Ontogenesis abnormalities 1) multynuclear oocytes; 2) 10% of sperms can be abnormal; 3) development of germ cells with 22 or 24 chromosomes Slide 30 The fusion of haploid gametes to form a new diploid cell is called fertilization or syngamy Fertilization may be external and internal Slide 31 Fertilization During fertilization two processes take place: During fertilization two processes take place: Eggs activation a wave of chemical reactions sweeps across the surface of the newly aroused egg, causing that surface to harden and present a barrier to the entry of any additional sperm. The eggs oxygen consumption skyrockets, as does its rate of protein synthesis. Eggs activation a wave of chemical reactions sweeps across the surface of the newly aroused egg, causing that surface to harden and present a barrier to the entry of any additional sperm. The eggs oxygen consumption skyrockets, as does its rate of protein synthesis. Syngamy male and female haploid nuclei converge and fuse to form the zygotes single diploid nucleus Syngamy male and female haploid nuclei converge and fuse to form the zygotes single diploid nucleus Slide 32 Fertilization 3 functions 3 functions transmission of genes restoration of the diploid number of chromosomes reduced during meiosis initiation of development in offspring Slide 33 Fertilization internal fertilization internal fertilization capacitation sperm must penetrate cumulus and zona pellucida extracellular matrix consisting of 3 types of glycoproteins one of these, ZP3, acts as a sperm receptor extracellular matrix consisting of 3 types of glycoproteins one of these, ZP3, acts as a sperm receptor Slide 34 Slide 35 Fertilization activates the egg, initiating metabolic processes activates the egg, initiating metabolic processes acrosomal reaction acrosomal reaction sperm are activated acrosomal process sperm and egg membranes fuse ion channels open, allowing Na + to flow in fast block to polyspermy cortical reaction cortical reaction eggs ER releases Ca 2+ into the cytosol at site of sperm entry Slide 36 Slide 37 Fertilization slow block to polyspermy Ca 2+ causes cortical granules underneath the plasma membrane to fuse Ca 2+ causes cortical granules underneath the plasma membrane to fuse mucopolysaccharides draw water into the space, swelling it mucopolysaccharides draw water into the space, swelling it vitelline layer becomes the fertilization membrane vitelline layer becomes the fertilization membrane Slide 38 Slide 39 Cleavage rapid divisions following fertilization rapid divisions following fertilization often skip G1 and G2 phases blastomeres result most animal eggs have polarity most animal eggs have polarity substances are heterogeneously distributed in cytoplasm vegetal pole vegetal pole animal pole animal pole Slide 40 K inds of cleavage: K inds of cleavage: Holoblastic (total cleavage) the zygote is divided completely. There are 1) uniform and 2) irregular holoblastic cleavage. They are haracteristic for isolecythal and telolecythal cells Holoblastic (total cleavage) the zygote is divided completely. There are 1) uniform and 2) irregular holoblastic cleavage. They are haracteristic for isolecythal and telolecythal cells Meroblastic (incomplete cleavage) the part of cytoplasm of an zygote is divided where yolk is absence. Meroblastic (incomplete cleavage) the part of cytoplasm of an zygote is divided where yolk is absence. There are: 1) discoidal and 2) superficial meroblastic cleavage. There are: 1) discoidal and 2) superficial meroblastic cleavage. In discoidal meroblastic cleavage the segmentation occurs on an animal pole in telolecythal cells. Birds eggs contain so much yolk that the small disc of cytoplasm on the surface is dwarfed by compasion. No cleavage of the massive yolk is possible, and all cell division is restricted to the small cytoplasmic disc, or blastodisc. In discoidal meroblastic cleavage the segmentation occurs on an animal pole in telolecythal cells. Birds eggs contain so much yolk that the small disc of cytoplasm on the surface is dwarfed by compasion. No cleavage of the massive yolk is possible, and all cell division is restricted to the small cytoplasmic disc, or blastodisc. In superficial meroblastic cleavage the segmentation occurs on an peripheric zone of cytoplasm in centrolecital cells. In superficial meroblastic cleavage the segmentation occurs on an peripheric zone of cytoplasm in centrolecital cells. Slide 41 In the man the cleavage of zygote is holoblastic, irregular and asynchronous Slide 42 Slide 43 Mammalian Development implantation implantation ICM forms flat disk with 2 layers (epiblast and hypoblast) embryo develops from epiblast cells, hypoblast forms yolk sac gastrulation gastrulation Slide 44 Slide 45 Gastrulation Gastrulation series of cell migrations to positions where they will form the three primary cell layers: 1) ectoderm (outside germinal layer); 2) endoderm (inside germinal layer) and 3) mesoderm (medium germinal layer) Slide 46 The germinal layers give rice to various tissues and organs of animals. It is called as histogenesis and organogenesis Slide 47 The fate of primary germinal layers is given bellow: The fate of primary germinal layers is given bellow: EctodermMesodermEndoderm Skin (epidermis), hair, nails, the eye lens, the pituitary gland, the epithelium of the nasal cavity, mouth, anal canal, nervous system, sense organs Connective tissue, bones, muscles, dermis, heart, blood vessels, gonads, excretory organs (kidneys) and the notochord (the dorsally located supportive rod found in all chordates, at least in embryonic stages) Digestive tract, lungs, liver, pancreas, thyroid gland, urinary bladder Slide 48 Slide 49 Mammalian Development 4 extraembryonic membranes form: 4 extraembryonic membranes form: chorion- from trophoblast, surrounds embryo and all other membranes amnion- from epiblast, encloses embryo in amniotic fluid yolk sac- from hypoblast, site of early blood cell formation allantois- outpocketing of embryos gut, incorporated into umbilical cord, forms blood vessels of umbilical cord Slide 50 Provisional organs are present during embryonic period and absent after birth. Provisional organs are present during embryonic period and absent after birth. Provisional organs in human embryo are: Provisional organs in human embryo are: an youlk sac an youlk sac an amnion an amnion an allantois an allantois a chorion. a chorion. Slide 51 The youlk sac the extraembryonic membrane that connects with the midgut. In human it is the first site of blood cell formation, but has no nutritive function. Slide 52 Chorion [Gr. membane] in human it is cellular, outermost extraembryonic membrane, composed of trophoblast lined with mesoderm, it develops villi about 2 weeks after fertilization, is vascularized by allantoic vessels a week later. Slide 53 Amnion [Gr. bowl ; membrane enveloping the fetus] the thin but tough extraembryonic membrane of reptilies, birds, and mammals that lines the chorion and contains the embryo and later the fetus, with the amniotic fluid around it. Slide 54 Placenta By the 23-rd day of human embryonic development, two other embryonic membranes the chorion and the allantois to give rise to a placenta By the 23-rd day of human embryonic development, two other embryonic membranes the chorion and the allantois to give rise to a placenta Exchange of material takes place in the placenta by diffusion between the blood of the mother and that of the embryo Exchange of material takes place in the placenta by diffusion between the blood of the mother and that of the embryo Within the placenta there is no mixing of maternal and fetal blood Within the placenta there is no mixing of maternal and fetal blood Slide 55 Human Gestation organogenesis fetus- all major structures are present human chorionic gonadotropin (hCG)- produced by embryo, maintains corpus luteum mucous plug formation in cervix negative feedback- cessation of ovulation and menstrual cycles Slide 56 Human Gestation 2nd trimester 2nd trimester increased movement of fetus hCG levels decline, leading to deterioration of corpus luteum placenta secretes progesterone uterus increases to visible size Slide 57 Human Gestation 3rd trimester 3rd trimester rapid growth of fetus estrogens and oxytocin initiate labor positive feedback- oxytocin stimulates prostaglandin secretion by placenta, leading to increased contractions Slide 58 Slide 59 In embrionic development of man there are following critical periods: In embrionic development of man there are following critical periods: Implantation (7 day after a fertilization) introduction of a zygote in a wall of an uterus Implantation (7 day after a fertilization) introduction of a zygote in a wall of an uterus Placentation (the end of 2 week of pregnancy) form at embryo of a placenta Placentation (the end of 2 week of pregnancy) form at embryo of a placenta Perinatal period (from 28 week of pregnancy to 7 day after birth) is transferring a fetus out of aqueous into air (on the average, about 280 days after the beginning of the mothers last regular menstrual period). Perinatal period (from 28 week of pregnancy to 7 day after birth) is transferring a fetus out of aqueous into air (on the average, about 280 days after the beginning of the mothers last regular menstrual period). Slide 60 Intrauterine pregnancy Slide 61 Any substance that can causes abnormal development of the egg in the mother's womb is called a teratogen. Any substance that can causes abnormal development of the egg in the mother's womb is called a teratogen. Growth is rapid, and each body organ has a critical period in which it is especially sensitive to outside influences. About 7% of all congenital defects are caused by exposure to teratogens. Growth is rapid, and each body organ has a critical period in which it is especially sensitive to outside influences. About 7% of all congenital defects are caused by exposure to teratogens. Drugs Drugs Alcohol. Alcohol. Slide 62 Chances of Down syndrome rapidly increase with parental age starting at about age 35 in women and 55 in men. Previously, it was thought there might be a tendency toward nondisjunction as a women ages because her eggs age as she does - a women is born with all the eggs she will ever have and they remain in suspended animation until one matures each month. Chances of Down syndrome rapidly increase with parental age starting at about age 35 in women and 55 in men. Previously, it was thought there might be a tendency toward nondisjunction as a women ages because her eggs age as she does - a women is born with all the eggs she will ever have and they remain in suspended animation until one matures each month. Ontogenesis abnormalities Slide 63 Slide 64 Slide 65 References: 1. Biology. Sylvia S. Mader, Wm. C. Brown Publishers: Dubuque, Lowa Melbourne, Australia Oxford, England, IV edition. p.169-181, 694-705. 2. Biology. Art notebook Sylvia S.Mader, Wm. C. Brown Publishers: Dubuque, Lowa Melbourne, Australia Oxford, England, IV edition. p.42-47. 3. Human biology. McMillan, Beverly. p. 310-327.