Foetus and placenta

High res available on request only, commercial use must be cleared, not for use by pro-life (or similar) organisations Human foetus at 11 to 12 weeks with the placenta in the background. At left is the yolk sac, which provided nutrition for the embryo before the placenta was fully formed.

Foetal head at nine weeks

High res available on request only, commercial use must be cleared, not for use by pro-life (or similar) organisations Human foetal head at nine weeks. Large numbers of V-shaped blood vessels are developing where the skull bones are fusing.

Foetus, 17 weeks

High res available on request only, commercial use must be cleared, not for use by pro-life (or similar) organisations Human foetus, 17 weeks. The developing fingernails can be seen.

Foetus, 20 weeks

High res available on request only, commercial use must be cleared, not for use by pro-life (or similar) organisations Human foetus at 20 weeks. At this stage the embryo measures approximately 20 centimetres.

Foetus, six months

High res available on request only, commercial use must be cleared, not for use by pro-life (or similar) organisations Human foetus at six months. At this stage the foetus measures approximately 30 centimetres.

Human foetus at four months

It measures around 20 centimetres.

Human foetus in amniotic sac at ten weeks

It measures approximately 30 millimetres. At this stage internal sexual differentiation takes place but external differences are not yet obvious. The placenta is at bottom.

Human foetus in amniotic sac at eight weeks

Human foetus at ten weeks

There is now more of the face below the eyes, but the lower jaw is not yet fully developed.

Close-up of the face of a human foetus at 17 weeks

The eyes are shut and will not open again until week twenty-six.

Human foetus in amniotic sac at eight weeks

The foetus at this stage is around 30 millimetres long and weighs about 8 grams. The heart, hand, head and feet have developed. The placenta is at bottom right.

Human foetus at ten weeks

At this stage the foetus measures about 4 centimetres in length. The eyelids are semi-shut. They will close completely in a few days. Human foetal movements begin at this time, but are not usually felt by the mother. Internal sexual differentiation takes place but external differences are not yet obvious.

Human foetal legs at 16 weeks

The foetus can now grab and pull the long umbilical cord. The skeleton consists mainly of flexible cartilage.

Human eye

Close-up of a human eye showing the iris and pupil. The iris, a coloured muscular ring, regulates the amount of light that enters the eye through the pupil (black).

Eye anatomy

Coloured scanning electron micrograph (SEM) showing part of the ciliary body (right) and iris (green) of an eye. The ciliary body is a ring-shaped structure that surrounds the iris and joins to ligaments that hold the lens in place behind the iris. It also contains the ciliary muscle that is contracted to alter the curvature of the lens and focus light on the retina at the back of the eye.

Cranial suture

Sutures are a type of rigid fibrous joint where the bones of the skull join. Sutures are only found in the skull.

Small intestine and mesentery

The mesentery is the connective tissue that attaches the small intestine and other organs to the rear abdominal wall.

Abdominal organs

Close-up of the abdominal organs of a newborn viewed from below. The coiled structure is the small intestine. The liver is red.

Infundibulum of the fallopian tube in a mature female

The infundibulum is the abdominal opening of the fallopian tube.

Epiglottis, endoscope view

The epiglottis is a flap of tissue located at the top of the larynx (voice box). During swallowing the larynx moves upwards so the epiglottis folds forward to form a lid, closing it off. This prevents food going down into the lungs and causing choking. Here it is in the open, or respiratory, position. The back of the tongue is in the foreground.

Human embryonic eye at 30 days

Coloured scanning electron micrograph (SEM).

Human embryonic brain at 22 days

Coloured scanning electron micrograph (SEM). Primitive nerve cells are already in place in the brain.

First cellular division, light micrograph

The first cell division of the zygote 24 hours after the egg cell was fertilised.

First cellular division, light micrograph

The first cell division of the zygote 24 hours after the egg cell was fertilised.

Fertilised egg

Light micrograph of the egg and sperm nuclei beginning to fuse.

Egg cell, light micrograph

At ovulation the egg rids itself of half its genetic information, sending it off to a peripheral polar body. Twenty-three chromosomes are left in the nucleus. The egg is surrounded by a layer of nutrient cells that will be transported along with it after ovulation into the fallopian tube.

ICSI in vitro fertilisation

Light micrograph of a human egg cell (ovum, round) being fertilised with a sperm cell (spermatozoon, centre) through the process of intracytoplasmic sperm injection (ICSI). ICSI is an in vitro fertilisation (IVF) procedure in which a single sperm is injected directly into an egg using a microinjector hermetic syringe (right). At left, a micromanipulator is being used to support the egg during the injection process.

Sperm and egg

Coloured scanning electron micrograph (SEM). Three to seven hours after ejaculation the sperm reaches the egg.

Human embryo in amniotic sac at six weeks

At this stage the embryo measures approximately 11 millimetres.

Human embryo at 46 days

The blood vessels of the umbilical cord can be seen. At this stage the embryo measures around 20 millimetres.