Embryonic development

Human Embryonic Development

Embryology The study of changes that take place in the embryo is known as embryology. Tooth buds appear for the baby teeth.

Half the DNA comes from the mother's egg and half from the father's sperm. Soon pockets form in the reticulum, which ultimately coalesce to form the chorionic cavity or extraembryonic coelom.

It is about 3 inches 7. These segmented tissue blocks differentiate into skeletal muscle, vertebrae, and dermis of all vertebrates. At one time, that idea may have seemed absurd.

The technique is similar to the one used by submarines to locate underwater structures. They are rich in both embryonic and maternal blood cells.

Embryonic Development

This lining of the uterine cavity or womb is now known as the deciduaand it produces a great number of large decidual cells in its increased interglandular tissue. The presomitic mesoderm gives rise to successive pairs of somites, identical in appearance that differentiate into the same cell types but the structures formed by the cells vary depending upon the anteroposterior e.

Near the narrow, posterior end, an opaque streak, called the primitive streakmakes its appearance and extends along the middle of the disk for about one-half of its length; at the anterior end of the streak there is a knob-like thickening termed the primitive node or knot, known as Hensen's knot in birds.

A normal gestation lasts anywhere from 37 to 42 weeks. Heavy RNA transcription using embryonic genes; up to this point the RNAs used were maternal stored in the unfertilized egg. Mammary and pituitary gland buds appear.

Although much less common than in vitro fertilization, embryonic transfer offers couples a higher success rate. Although this is not completly accurate, the document goes on to describe various stages of embryo development. Next the embryos are flushed from the uterus with a saline salt-water solution.

The embryo is what will develop into your baby. Baby begins to move and stretch. Cells begin to collect along the embryo's back in a formation known as the neural tube, a structure that will eventually develop into the brain and spinal cord.

Embryo and embryonic development

Today, the practice is common. The implantation is assisted by hydrolytic enzymes that erode the epithelium. Weeks 31 to 34 Your baby grows quickly and gains a lot of fat.

Nails grow to the end of baby's fingers. The embryo appears more human by this point. The lungs start to form. Finally, inthe discovery of the molecular structure of DNA deoxyribonucleic acid by the American biologist James Watson — and the English chemist Francis Crick — provided a chemical explanation of changes that take place during fertilization and development.

In humans, embryonic transfer is sometimes used as part of a fertility program. It divides to form two cells, then four, then eight, and so on.

This period is also considered the organogenic period, when most organs within the embryo have begun to form. The identical cells formed by the early divisions of the zygote are beginning to take on the different characteristic of muscle, blood, nerve, bone, and other kinds of cells.

These techniques can be used to determine the presence of problems in the growing embryo. This is when you are most likely to conceive if you have unprotected intercourse.

Rhythmic breathing occurs, but baby's lungs are not fully mature. This substance helps the air sacs fill with air. A process used to obtain "pictures" of the developing embryo using ultrasound. The inner cell mass remains in contact, however, with the trophoblast at one pole of the ovum; this is named the embryonic polesince it indicates the location where the future embryo will develop.

During the eighth week, remarkable development occurs.


As the zygote and its daughter cells divide, they start to become specialized, meaning they begin to take on characteristic structures and functions that will be needed in the adult plant or animal.

The earliest formal writings on embryology can be traced to about B. The skin is not as wrinkled as fat forms under the skin.


Early in this week, tooth buds appear. Waste products from the embryo will diffuse across the placenta.Pre-Embryonic Development. Ovulation, fertilization, pre-embryonic development, and implantation occur at specific locations within the female reproductive system in a time span of approximately 1 week.

Human prenatal development is divided into an embryonic period and a fetal period. The embryonic period begins with fertilization and ends eight weeks later. The staging of human embryos was introduced in by Franklin P.

Mall at the Department of Embryology of the Carnegie Institution of Washington. Chorionic villus sampling (CVS) is the most sophisticated modern technique used to assess possible inherited, genetic defects.

Fetal development

This test is usually performed between the sixth and eighth week of embryonic development. Embryogenesis is the process by which the embryo forms and develops.

In mammals, the term refers chiefly to early stages of prenatal development, whereas the terms fetus and fetal development describe later stages. Embryogenesis starts with the fertilization of the egg cell (ovum) by a sperm cell, (spermatozoon).

Once fertilized, the ovum is referred. Human embryonic development depends on stem cells. During the course of development, cells divide, migrate, and specialize. Early in development, a group of cells called the inner cell mass (ICM) forms.

These cells are able to produce all the tissues of the body. Later in development, during. This page shows some key events of human development during the embryonic period of the first eight weeks (weeks 1 - 8) following fertilization.

This period is also considered the organogenic period, when most organs within the embryo have begun to form.

Embryonic development
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