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EMBRYOLOGY INTRODUCTION
Dr. Hina KhanAssistant Professor
Anatomy
Objectives
Definition of Developmental
Anatomy
Brief history of Developmental
Anatomy
Nomenclatures in
developmental Anatomy
Embryology in the Middle Ages
Holy Quran (seventh century AD), mentions that
human beings are produced from a mixture of
secretions from the male and female. Several
references are made to the creation of a human
being from a nutfa (small drop). It also states that
the resulting organism settles in the womb like a
seed, 6 days after its beginning.
Ancient Views of Human Embryology
Egyptians approximately 3000 B. C., knew of methods for
incubating birds' eggs, but did not produce record.
Sanskrit treatise Hindi holy book also describes ancient
ideas concerning the embryo.
Greek scholars made many important contributions to the
science of embryology.
The first recorded embryologic studies are in the books of
Hippocrates of Cos, the famous Greek physician (circa
460-377 B. C.), who is regarded as the Father of Medicine.
He explained the developed of embryo.
Terms
Developmental Embryo
It is the field of embryology
concerned with the changes that
cells, tissues, organs, and the body as a
whole undergo from a germ cell of
each parent to the resulting adult.
Trait
Any genetically determined
characteristics is called trait
HOMOZYGOTE
Relating to a cell that has two identical
alleles for a particular trait at
corresponding positions on homologous
chromosomes.
Heterozygote
An individual having different alleles at a
given locus on the homologous
chromosomes is called heterozygote
Dominant Triat
A trait expressed in the homozygous as
well as in the heterozygous
Recessive triat
A trait expressed only in the heterozygote
Genotype
The genetic constitution of an organisum
Phenotype
The observable characteristics of an
individual
Gene Expression
A process by which the information
contained in the gene is converted to
molecules that determine the properties
of cells.
Replication
Production of exact copy of strand of
DNA or (RNA)
Transcription
In which the Single strand of RNA is
synthesized from double strand of DNA
Translation
The conversion of genetic information
contained in RNA in to (protein)
polypeptide chain
In Vivo – In Vitro
In Vitro: any
sequence of
events occur
outside the body
In Vivo: any sequence
of events occur inside
the body
Oocyte (L. ovum, egg)
The female germ or sex
cells are produced in
the ovaries. When
mature, the oocytes are
called secondary
oocytes or mature
oocytes.
Ovaries
Paired female internal
Reproductive organs,
present near the
Uterus
Uterus
Female Internal
Reproductive
organ, divided into:
Fallopian Tubes
Body of Uterus
Cervix
Fallopian Tubes
They are tube like
structures, lying near
to the ovaries, help in
the transport of ovum,
Fallopian tube divided
into four parts
This tube is also site
for the fertilization of
Ovum by male gametes
the “sperms”
Male Gametes
Male Gametes are
called as sperms,
they are produced
in the seminiferous
tubules of testis
Testes
Paired male internal
genitilia present in the
scrotum outside the body
Containing seminiferous
tubules which provide the
male gametes
Fertilization
Male gametes produced by
the Seminiferous tubules
of testis, deposited into
female genital tract and
only one penetrate the
ovum in the ampulla of
fallopian tube to form the
Zygote
Zygote.
This cell results from
the union of an oocyte
and a sperm during
fertilization. A zygote
or embryo is the
beginning of a new
human being.
Embryo (Gr. embryon)
The developing human during its
early stages of development.
The embryonic period extends to
the end of the eighth week (56
days), by which time the
beginnings of all major
structures are present.
Size of Embryo
The size of embryos is
given as crown-rump
length, which is measured
from the vertex of the
cranium (crown of head) to
the rump (buttocks).
Fetus (L., unborn offspring)
From 9th week to 40th week of
gestational age or 11th week to
38th week after fertilization the
developing baby is called as the
fetus.
During the fetal period (ninth
week to birth), differentiation and
growth of the tissues and organs
formed during the embryonic
period occur.
Conceptus
Conceptus (L. conceptio,
derivatives of zygote). The
embryo and its adnexa (L.,
appendages or adjunct
parts) or associated
membranes (i.e., the
products of conception).
The conceptus includes all
structures that develop
from the zygote, both
embryonic and
extraembryonic.
Implantation
The process during which the
blastocyst attaches to the
endometrium, the mucous
membrane or lining of uterus,
and subsequently embeds in it.
The preimplantation period of
embryonic development is the
time between fertilization and
the beginning of implantation, a
period of approximately 6 days.
Age of Developing Baby Gestational Age: the age of
baby from the first day of
last menstrual cycle to the
birth of bay. It is about 40
weeks or 10 lunar months or
380 days.
Fertilization Age: age of
baby after the fertilization up
to birth of baby. It is 38
weeks or 366 days. It is two
week shorter than the
gestational age.
Trimester The entire pregnancy
divided into three trimesters, each trimester consists of three moths.
The first trimester is very important in which most of organs of embryo developed.
In second and third trimester of pregnancy the differentiation and morphogenesis of already formed organs will occur
Postnatal Period
The period
occurring after
birth. Explanations
of frequently used
developmental
terms and periods
follow.
Abortion (L. aboriri, to miscarry)
A premature stoppage of
development and expulsion of a
conceptus from the uterus or
expulsion of an embryo or fetus
before it is viable-capable of living
outside the uterus.
Abortion occurs before the fetus
becomes viable that is before the six
months of development
Premature
Birth of baby, usually
after six months.
Baby can survive by
keeping in an incubator
by providing the
artificial respiration
The survival rates
depends upon the age
of fetus
Parturition
It is the process
of birth of baby
through the birth
canal of woman