Fetal development and genetics

Stages of Fetal Development

Pre-embryonic stage, Embryonic stage, and Fetal stage

Fetal stage

end of eighth week until birth

Pre-embryonic stage

fertilization through second week

Pre-embryonic stage: Cells

Fertilization; Cleavage; Morula

Pre-embryonic stage: after fertilization embryo

Blastocyst and trophoblast

Pre-embryonic stage: is the stage of

Implantation

Embryonic stage

End of second week through eighth week

Embryonic stage: Basic structure of

major body organs and main external features are formed

Fetal stage

end of eighth week until birth

Embryonic Layers

Ectoderm, Mesoderm and Endoderm

Endoderm

forms the respiratory system, liver, pancreas and digestive system

Mesoderm

forms the skeletal, urinary, circulatory
and reproductive organs

Ectoderm

forms the central nervous system, special
senses, skin and the glands

Hormones produced by the Placenta

HCG, Prolactin, Human placental lactogen (hPL), Estrogen, Progesterone, Relaxin

Functions of the Placenta: Serving as

the interface between the mother and fetus

Functions of the Placenta: making

hormones to control the physiology of the mother

Functions of the Placenta: Protecting

the fetus from immune attack by the mother

Functions of the Placenta: Removing

the waste products from the fetus

Functions of the Placenta: Inducing

the mother to bring more food to the placenta

Functions of the Placenta: Producing

hormones that mature into fetal organs

Umbilical Cord: formed

from the amnion

Umbilical Cord: lifeline

from the mother to the growing embryo

Umbilical Cord: contains

one large vein and two small arteries

Umbilical Cord: A special type of tissue called

Wharton jelly surrounds the vein and arteries to prevent cord compression

Umbilical Cord: At term

the average cord will be about 22 inchlength and about 1inch width

Role of Amniotic Fluid: Helps maintain

a constant body temperature for the fetus

Role of Amniotic Fluid: Permits

symmetric growth and development

Role of Amniotic Fluid: Cushions

the fetus from trauma

Role of Amniotic Fluid: Allows

the umbilical cord to be relatively free of compression

Role of Amniotic Fluid: Promotes

fetal movement to enhance musculoskeletal

Fetal Circulation

Blood from the placenta to and through the fetus and then back to the placenta

Fetal Circulation: Three shunts

Ductus venous, Ductus arteriosus, Foramen ovale

Foramen ovale

anatomic opening between the right and left atrium

Ductus arteriosus

connects the main pulmonary artery to the aorta

Ductus venous

connects the umbilical vein to the inferior vena cava

Genetics and Advances in Genetic Knowledge

Study of heredity and its variation, Part of perinatal care for decades, Genetic testing, Gene therapy

Pharmacogenomics

study of genetic and genomic influences on pharmacodynamics and pharmacotherapeutics

Human Genome Project

Internal 13-year effort started in 1990 to produce a comprehensive sequence of the human genome

Human Genome Project: The goal

map, sequence, and determine the function of all human genes

Human Genome Project: Genome

a person’s genetic blueprint determining:
Genotype and Phenotype

Phenotype

observed outward characteristics

Genotype

genes inherited from parents

Inheritance

Genes, chromosome, Karyotype

Inheritance: chromosome

long, continuous strand of DNA carrying genetic information

Inheritance: Karyotype

pictorial analysis of number, form and size of chromosomes

Inheritance: Genes

individual units of heredity of all traits

Genes: Organized into

long segments of DNA that occupies a specific location on a chromosome

Genes: Determination of a

particular characteristic in an organism; physical and mental characteristics of human

Karyotype: Commonly uses

white blood cells and fetal cells in amniotic fluid

Karyotype: Chromosomes are numbered from

largest to smallest, 1 to 22

Karyotype: Chromosomes with

sex chromosomes by X and Y