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