1) The document discusses various mechanisms of sexual and asexual reproduction in organisms. It describes gametogenesis, fertilization, and the main stages of ontogenesis including cleavage, gastrulation, and formation of organs and systems.
2) The two main types of reproduction are asexual, which produces offspring genetically identical to the parent, and sexual, which involves meiosis and fusion of male and female gametes to create offspring with genetic material from both parents.
3) Fertilization is the fusion of haploid gametes to form a diploid zygote, which then undergoes cleavage, gastrulation, and organogenesis during development.
INTRODUCTION
DEFINATION
GAMETES
STRUCTURE OF GAMETES
SPERM
OVUM
RECOGNITION OF EGG AND SPERM
CAPACITATION
ACROSOME REACTION
SPECIES-SPECIFIC RECOGNITION
GAMETE BINDING AND RECOGNITION
GAMETE FUSION
PREVENTION OF POLYSPERMY
ACTIVATION OF GAMETE METABOLISM
FUSION OF THE GENETIC MATERIAL
SIGNIFICANCE OF FERTILIZATION
CONCLUSIONS
REFERENCES
INTRODUCTION
DEFINATION
GAMETES
STRUCTURE OF GAMETES
SPERM
OVUM
RECOGNITION OF EGG AND SPERM
CAPACITATION
ACROSOME REACTION
SPECIES-SPECIFIC RECOGNITION
GAMETE BINDING AND RECOGNITION
GAMETE FUSION
PREVENTION OF POLYSPERMY
ACTIVATION OF GAMETE METABOLISM
FUSION OF THE GENETIC MATERIAL
SIGNIFICANCE OF FERTILIZATION
CONCLUSIONS
REFERENCES
An oocyte is a female gametocyte or germ cell involved in reproduction.It is an immature ovum or an egg
An oocyte is produced in the ovary during female gametogenesis.The female germ cells produce a primordial germ cell pgc which undergoes mitosis to form an oogonium
During oogenesis the oogonium becomes a primary oocyte
Oogenesis consists of several sub processes – oocytogenesis, ootidogenesis and the maturation to form an ovum
Folliculogenesis is a separate sub process and supports all three oogenetic sub process
An oocyte is a female gametocyte or germ cell involved in reproduction.It is an immature ovum or an egg
An oocyte is produced in the ovary during female gametogenesis.The female germ cells produce a primordial germ cell pgc which undergoes mitosis to form an oogonium
During oogenesis the oogonium becomes a primary oocyte
Oogenesis consists of several sub processes – oocytogenesis, ootidogenesis and the maturation to form an ovum
Folliculogenesis is a separate sub process and supports all three oogenetic sub process
Ethanol (CH3CH2OH), or beverage alcohol, is a two-carbon alcohol
that is rapidly distributed in the body and brain. Ethanol alters many
neurochemical systems and has rewarding and addictive properties. It
is the oldest recreational drug and likely contributes to more morbidity,
mortality, and public health costs than all illicit drugs combined. The
5th edition of the Diagnostic and Statistical Manual of Mental Disorders
(DSM-5) integrates alcohol abuse and alcohol dependence into a single
disorder called alcohol use disorder (AUD), with mild, moderate,
and severe subclassifications (American Psychiatric Association, 2013).
In the DSM-5, all types of substance abuse and dependence have been
combined into a single substance use disorder (SUD) on a continuum
from mild to severe. A diagnosis of AUD requires that at least two of
the 11 DSM-5 behaviors be present within a 12-month period (mild
AUD: 2–3 criteria; moderate AUD: 4–5 criteria; severe AUD: 6–11 criteria).
The four main behavioral effects of AUD are impaired control over
drinking, negative social consequences, risky use, and altered physiological
effects (tolerance, withdrawal). This chapter presents an overview
of the prevalence and harmful consequences of AUD in the U.S.,
the systemic nature of the disease, neurocircuitry and stages of AUD,
comorbidities, fetal alcohol spectrum disorders, genetic risk factors, and
pharmacotherapies for AUD.
Ozempic: Preoperative Management of Patients on GLP-1 Receptor Agonists Saeid Safari
Preoperative Management of Patients on GLP-1 Receptor Agonists like Ozempic and Semiglutide
ASA GUIDELINE
NYSORA Guideline
2 Case Reports of Gastric Ultrasound
Explore natural remedies for syphilis treatment in Singapore. Discover alternative therapies, herbal remedies, and lifestyle changes that may complement conventional treatments. Learn about holistic approaches to managing syphilis symptoms and supporting overall health.
Title: Sense of Smell
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the primary categories of smells and the concept of odor blindness.
Explain the structure and location of the olfactory membrane and mucosa, including the types and roles of cells involved in olfaction.
Describe the pathway and mechanisms of olfactory signal transmission from the olfactory receptors to the brain.
Illustrate the biochemical cascade triggered by odorant binding to olfactory receptors, including the role of G-proteins and second messengers in generating an action potential.
Identify different types of olfactory disorders such as anosmia, hyposmia, hyperosmia, and dysosmia, including their potential causes.
Key Topics:
Olfactory Genes:
3% of the human genome accounts for olfactory genes.
400 genes for odorant receptors.
Olfactory Membrane:
Located in the superior part of the nasal cavity.
Medially: Folds downward along the superior septum.
Laterally: Folds over the superior turbinate and upper surface of the middle turbinate.
Total surface area: 5-10 square centimeters.
Olfactory Mucosa:
Olfactory Cells: Bipolar nerve cells derived from the CNS (100 million), with 4-25 olfactory cilia per cell.
Sustentacular Cells: Produce mucus and maintain ionic and molecular environment.
Basal Cells: Replace worn-out olfactory cells with an average lifespan of 1-2 months.
Bowman’s Gland: Secretes mucus.
Stimulation of Olfactory Cells:
Odorant dissolves in mucus and attaches to receptors on olfactory cilia.
Involves a cascade effect through G-proteins and second messengers, leading to depolarization and action potential generation in the olfactory nerve.
Quality of a Good Odorant:
Small (3-20 Carbon atoms), volatile, water-soluble, and lipid-soluble.
Facilitated by odorant-binding proteins in mucus.
Membrane Potential and Action Potential:
Resting membrane potential: -55mV.
Action potential frequency in the olfactory nerve increases with odorant strength.
Adaptation Towards the Sense of Smell:
Rapid adaptation within the first second, with further slow adaptation.
Psychological adaptation greater than receptor adaptation, involving feedback inhibition from the central nervous system.
Primary Sensations of Smell:
Camphoraceous, Musky, Floral, Pepperminty, Ethereal, Pungent, Putrid.
Odor Detection Threshold:
Examples: Hydrogen sulfide (0.0005 ppm), Methyl-mercaptan (0.002 ppm).
Some toxic substances are odorless at lethal concentrations.
Characteristics of Smell:
Odor blindness for single substances due to lack of appropriate receptor protein.
Behavioral and emotional influences of smell.
Transmission of Olfactory Signals:
From olfactory cells to glomeruli in the olfactory bulb, involving lateral inhibition.
Primitive, less old, and new olfactory systems with different path
Report Back from SGO 2024: What’s the Latest in Cervical Cancer?bkling
Are you curious about what’s new in cervical cancer research or unsure what the findings mean? Join Dr. Emily Ko, a gynecologic oncologist at Penn Medicine, to learn about the latest updates from the Society of Gynecologic Oncology (SGO) 2024 Annual Meeting on Women’s Cancer. Dr. Ko will discuss what the research presented at the conference means for you and answer your questions about the new developments.
These lecture slides, by Dr Sidra Arshad, offer a quick overview of physiological basis of a normal electrocardiogram.
Learning objectives:
1. Define an electrocardiogram (ECG) and electrocardiography
2. Describe how dipoles generated by the heart produce the waveforms of the ECG
3. Describe the components of a normal electrocardiogram of a typical bipolar leads (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
Study Resources:
1. Chapter 11, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 9, Human Physiology - From Cells to Systems, Lauralee Sherwood, 9th edition
3. Chapter 29, Ganong’s Review of Medical Physiology, 26th edition
4. Electrocardiogram, StatPearls - https://www.ncbi.nlm.nih.gov/books/NBK549803/
5. ECG in Medical Practice by ABM Abdullah, 4th edition
6. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
New Drug Discovery and Development .....NEHA GUPTA
The "New Drug Discovery and Development" process involves the identification, design, testing, and manufacturing of novel pharmaceutical compounds with the aim of introducing new and improved treatments for various medical conditions. This comprehensive endeavor encompasses various stages, including target identification, preclinical studies, clinical trials, regulatory approval, and post-market surveillance. It involves multidisciplinary collaboration among scientists, researchers, clinicians, regulatory experts, and pharmaceutical companies to bring innovative therapies to market and address unmet medical needs.
Pulmonary Thromboembolism - etilogy, types, medical- Surgical and nursing man...VarunMahajani
Disruption of blood supply to lung alveoli due to blockage of one or more pulmonary blood vessels is called as Pulmonary thromboembolism. In this presentation we will discuss its causes, types and its management in depth.
Lung Cancer: Artificial Intelligence, Synergetics, Complex System Analysis, S...Oleg Kshivets
RESULTS: Overall life span (LS) was 2252.1±1742.5 days and cumulative 5-year survival (5YS) reached 73.2%, 10 years – 64.8%, 20 years – 42.5%. 513 LCP lived more than 5 years (LS=3124.6±1525.6 days), 148 LCP – more than 10 years (LS=5054.4±1504.1 days).199 LCP died because of LC (LS=562.7±374.5 days). 5YS of LCP after bi/lobectomies was significantly superior in comparison with LCP after pneumonectomies (78.1% vs.63.7%, P=0.00001 by log-rank test). AT significantly improved 5YS (66.3% vs. 34.8%) (P=0.00000 by log-rank test) only for LCP with N1-2. Cox modeling displayed that 5YS of LCP significantly depended on: phase transition (PT) early-invasive LC in terms of synergetics, PT N0—N12, cell ratio factors (ratio between cancer cells- CC and blood cells subpopulations), G1-3, histology, glucose, AT, blood cell circuit, prothrombin index, heparin tolerance, recalcification time (P=0.000-0.038). Neural networks, genetic algorithm selection and bootstrap simulation revealed relationships between 5YS and PT early-invasive LC (rank=1), PT N0—N12 (rank=2), thrombocytes/CC (3), erythrocytes/CC (4), eosinophils/CC (5), healthy cells/CC (6), lymphocytes/CC (7), segmented neutrophils/CC (8), stick neutrophils/CC (9), monocytes/CC (10); leucocytes/CC (11). Correct prediction of 5YS was 100% by neural networks computing (area under ROC curve=1.0; error=0.0).
CONCLUSIONS: 5YS of LCP after radical procedures significantly depended on: 1) PT early-invasive cancer; 2) PT N0--N12; 3) cell ratio factors; 4) blood cell circuit; 5) biochemical factors; 6) hemostasis system; 7) AT; 8) LC characteristics; 9) LC cell dynamics; 10) surgery type: lobectomy/pneumonectomy; 11) anthropometric data. Optimal diagnosis and treatment strategies for LC are: 1) screening and early detection of LC; 2) availability of experienced thoracic surgeons because of complexity of radical procedures; 3) aggressive en block surgery and adequate lymph node dissection for completeness; 4) precise prediction; 5) adjuvant chemoimmunoradiotherapy for LCP with unfavorable prognosis.
Acute scrotum is a general term referring to an emergency condition affecting the contents or the wall of the scrotum.
There are a number of conditions that present acutely, predominantly with pain and/or swelling
A careful and detailed history and examination, and in some cases, investigations allow differentiation between these diagnoses. A prompt diagnosis is essential as the patient may require urgent surgical intervention
Testicular torsion refers to twisting of the spermatic cord, causing ischaemia of the testicle.
Testicular torsion results from inadequate fixation of the testis to the tunica vaginalis producing ischemia from reduced arterial inflow and venous outflow obstruction.
The prevalence of testicular torsion in adult patients hospitalized with acute scrotal pain is approximately 25 to 50 percent
The prostate is an exocrine gland of the male mammalian reproductive system
It is a walnut-sized gland that forms part of the male reproductive system and is located in front of the rectum and just below the urinary bladder
Function is to store and secrete a clear, slightly alkaline fluid that constitutes 10-30% of the volume of the seminal fluid that along with the spermatozoa, constitutes semen
A healthy human prostate measures (4cm-vertical, by 3cm-horizontal, 2cm ant-post ).
It surrounds the urethra just below the urinary bladder. It has anterior, median, posterior and two lateral lobes
It’s work is regulated by androgens which are responsible for male sex characteristics
Generalised disease of the prostate due to hormonal derangement which leads to non malignant enlargement of the gland (increase in the number of epithelial cells and stromal tissue)to cause compression of the urethra leading to symptoms (LUTS
New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
Target Audience
Hematology/oncology fellows, attending faculty, and other health care professionals involved in the treatment of patients with mantle cell lymphoma (MCL).
Learning Objectives
1.) Identify clinical and biological prognostic factors that can guide treatment decision making for older adults with MCL
2.) Evaluate emerging data on targeted therapeutic approaches for treatment-naive and relapsed/refractory MCL and their applicability to older adults
3.) Assess mechanisms of resistance to targeted therapies for MCL and their implications for treatment selection
2. PLAN
• Asexual and sexual reproductions in
unicellular and multicellular organisms
• Gametogenesis: spermatogenesis and
oogenesis
• Morphogenetic specialization of sex cells:
a sperm and an ovum
• Fertilization.
• The periods of ontogenesis
6. Types of reproduction
asexual sexual
Organisms single-cellular organisms,
multi-cellular organisms:
one ore more somatic
cells of parental
organisms;
Parental organisms
forms gametes
Parents One person Two persons
Offspring's genetically identical to its
parent like a xero copy.
genetically different
from parents
Cell formation Mitosis Meiosis
7. Asexual is a reproduction without
the fusion of sexual cells,
identical offspring grows directly
from a one or few body cells,
which divides mitotically
9. Forms of asexual reproduction
in single-cellular organisms:
• binary fission – parent cell splits in two
cells by mitosis
• endogony -endogony - in parent cell forms only twoin parent cell forms only two
daughter cells by internal buddingdaughter cells by internal budding
• schizogony -schizogony - formation a great amount offormation a great amount of
daughter cells in parent celldaughter cells in parent cell
13. asexual reproduction
• budding - after karyokinesis the special
region in parent cell rapid grows and
organized into new organism.
• sporogony -sporogony - is reproduction by theis reproduction by the
sporesspores
15. Forms of asexual reproduction in
multi-cellular organisms
• sporogony - is reproduction by the spores
• budding -parent produces a bud, bud gets
detached and develops into offspring
which is identical to parent
• polyembrionypolyembriony -- the production of two orthe production of two or
more embryo's from the one zygotemore embryo's from the one zygote
18. Fragmentation
In this form, the body of the parent
breaks into distinct pieces, each of
which can produce an offspring.
Pieces of coral broken off in storms
can grow into new colonies.
A new starfish can grow from
one detached arm.
23. 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
24. Forms of sexual reproduction
in single-cellular organisms
• Conjugation
• Copulation
25. 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
32. Methods of sexual reproduction:
Pollination
External Fertilization
Internal Fertilization
33. Sexual Reproduction in Plants
(Pistil)
Male Parts
Female Parts
pollen (male) + ovule (female) → single-celled zygote → multi-celled
embryo (contained in a seed) → new individual
34. External Fertilization
• External fertilization usually requires a
medium such as water, which the
sperms can use to swim towards the
egg cell. External fertilization usually
occur in fish and amphibians.
• The females lay the eggs in the water
and the male squirts the sperm
in the same area.
36. Sexual Reproduction in Animals
• involves specialized sex cells called gametes
• the union of a male and female gamete results in the
formation of a zygote that develops into a new individual
37. Sexual Reproduction Summary
MaleMale
GameteGamete
FemaleFemale
GameteGamete
Type ofType of
UnionUnion
Result ofResult of
UnionUnion
FinalFinal
ResultResult
PlantsPlants pollen ovule
(egg)
pollination single cell
zygote
multi-cell
embryo
(in seed)
AnimalsAnimals sperm egg fertilization single cell
zygote
multi-cell
embryo
38. Asexual
Reproduction
– involves only 1 parent
– offspring genetically
identical to parent
– involves regular body
cells
– its quick
Sexual
Reproduction
– involves 2 parents
– offspring genetic mix
of both parents
– involves specialized
sex cells
– its slow
39. Some Organisms do Both
• most plants that produce seeds (sexual
reproduction) can also reproduce
asexually by things like cuttings or runners
• this gives them an advantage for survival
sponges and hydra mosses
40. Gametogenesis
• process of formation and development of
sex cells
• the aim is to prepare sex cells to their
assimilation or fusion that is a basis of
fertilization
• during gametogenesis, the chromosome
number is reduced by half and shape of
cells is altered
41. Spermatogenesis
maturation process of male gametes; includes
the series of events leading to transformation
of spermatogonia into haploid spermatids;
these then develop into ripe (mature) sperms
by gradual process known as spermiogenesis
(= histological differentiation of spermatids)
42.
43. Oogenesis
maturation process of female
gametes
is bound to the ovary (ovarian cortex) -
ovarian follicles
2 phases:
oocytogenesis
meiosis
46. Two types of sex cells are
distinguished:
• Male cell is spermatozoon or sperm
• Female cell is ovum or ovocyte
47.
48. 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.
(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 centrolecythal ovum has the central
nucleus and around it settles down yolk as
grains. (insects).
49.
50. The fusion of haploid gametes to form a new
diploid cell is called fertilization or syngamy
During fertilization two processes take place:During fertilization two processes take place:
Egg’s activationEgg’s activation – a wave of chemical reactions sweeps across the– a wave of chemical reactions sweeps across the
surface of the newly aroused egg, causing that surface to harden andsurface of the newly aroused egg, causing that surface to harden and
present a barrier to the entry of any additional sperm. The egg’s oxygenpresent a barrier to the entry of any additional sperm. The egg’s oxygen
consumption skyrockets, as does its rate of protein synthesis.consumption skyrockets, as does its rate of protein synthesis.
SyngamySyngamy – male and female haploid nuclei converge and fuse to form– male and female haploid nuclei converge and fuse to form
the zygote’s single diploid nucleusthe zygote’s single diploid nucleus
51.
52. Ontogenesis
• the development of the individual
organism.
• It includes the set of morphological,
phisiological and biochenical
transformations from the moment of
germing up to death.
53. The ontogenesis of multicellular
organisms is divided in two periods
1 embryonic
2 postembryonic.
For higher animals and man there are:
1) prenatal (before birth)
2) posnatal (after birth) periods of development
54. Human developmental periods
• Progenesis - is a period of
maturation of specialized
generative cells- gametes. This
maturation process is called
spermatogenesis in males and
oogenesis in female
55. Prenatal period
Prenatal period begins when an oocyte from female is fertilized
by a sperm from male with the formation of zygote.
Main stages of prenatal period:
• Fertilization is fusion of a female and male gamete.
• Cleavage is the series of rapid cell divisions of the zygote with
the formation of blastula
• Gastrulation is the formative process by which the three germ
embryonic layers are established in embryos (ectoderm,
mesoderm and endoderm).
• Formation of axial organs: notochord, neural tube, and
primordial gut.
• Histogenesis
• Organogenesis
• Systemogenesis
56. Kinds 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
• 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.
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.
57.
58. In the man the cleavage of zygote is
holoblastic, irregular and asynchronous
59. - morula (from latin morus – mulberry) the solid ball
consisting of 12 to 16 blastomeres blastomeres = cells that
result in process of cleavage of the zygote, blastomeres are
genetic equal and they do not substantially differ each other,
prospective properties or developmental potency of
blastomeres are the same, each of them can give rise to a new
individuum
-
60. gastrula - the bilaminar pre-embryonic stage, in which the main
body axis and polarity begin to become apparent, the bilaminar
stage develops on day 7 and lasts to the end of the second week
after fertilization
blastocyst the stage with a cavity inside that is filled with fluid, 2
different cell populations differentiate at the first time in
development: trophoblast cells + inner cell mass or embryoblast
cells, during the day 5
61.
62. Gastrulation - 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)
63. The germinal layers give rice
to various tissues and organs
of animals. It is called as
histogenesis and
organogenesis
64. The fate of primary germinal layers is given bellow:
Ectoderm Mesoderm Endoderm
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
65.
66. Mammalian Development
• 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 embryo’s gut,
incorporated into umbilical cord, forms blood
vessels of umbilical cord
67. • Provisional organs
are present during
embryonic period
and absent after
birth.
• Provisional organs
in human embryo
are:
an youlk sac
an amnion
an allantois
a chorion.
68. 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
• Within the placenta there is
no mixing of maternal and
fetal blood
69.
70.
71. 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;
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)
3. Intrauterine ontogenesis – is development of an
organism inside a maternal organism. (mammalian).
72.
73. Phases of the postnatal development in the human
infancy – from the birth to the end of the first year of the age (the first two
weeks of infancy are called as the newborn or neonatal period)
childhood - from 13 month until 12 to 13 years; the primary teeth appear
and are replaced by the secondary or permanent teeth
puberty - is the period between 12-15 years in girls and 13-16 years in
boys, during which secondary sexual characteristics develop
adolescence - follows the puberty and ends 3-4 years after it; the
organism reaches sexual but also physical, mental and emotional maturity
adulthood - a period in which developmental changes occur very slowly
and are mostly characterized by selective loss of highly specialized cells
and tissues
postnatal development of the human is studied and treated with various
medical branches
74. 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
• 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 mother’s
last regular menstrual period).
75. • Any substance that can causes abnormal
development of is called a teratogen.
Editor's Notes
Mosses produce asexual spores in the early part of their life cycle and then egg and sperm cells are produced in a later part of the same cycle.