Different techniques showing sperm and egg cells

There are many ways of looking at cells and capturing what they look like. We've chosen 12 different images of sperm and egg cells and the parts of the body in which they develop to show how cells can be visualised with different techniques.

Image research by Laura Pastorelli; captions by Chrissie Giles, adapted from Wellcome Images.

Human egg

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A false-colour scanning electron micrograph of a human egg cell (gold) surrounded by cumulus cells (orange). Cumulus cells are specialised cells that nourish the large egg cell while it grows in the ovarian follicle.
Credit: Yorgos Nikas, Wellcome Images.

Secondary oocyte during in vitro fertilisation

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A human secondary oocyte (which will later become an egg cell) during in vitro fertilisation, viewed with a light microscope using Nomarski optics, a technique used to highlight cell structure. The small cell at the bottom left is a polar body.
Credit: Spike Walker, Wellcome Images.

Egg cell in follicle

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Light microscopy image of a transverse cross-section of an immature egg cell (oocyte) in a maturing follicle. Once a month, during the female menstrual cycle, an oocyte matures in one of the many ovarian follicles. As the follicle matures it increases in size, and different cell types are recruited to the developing follicle to support the oocyte before ovulation.
Credit: Dr Ivor Mason, King’s College London, Wellcome Images.

Egg and sperm

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Light microscopy image showing sperm and an egg cell (or ovum) at the moment of conception during in vitro fertilisation. The egg is surrounded by protective cumulus cells around the outside surface, coloured yellow. The sperm need to penetrate these cells and the membrane surrounding the egg, called the zona pellucida, if successful fertilisation is to occur.
Credit: Spike Walker, Wellcome Images.

Intracytoplasmic sperm injection

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Digital artwork showing intracytoplasmic sperm injection (ICSI). ICSI is a method of in vitro fertilisation (IVF) that is used to treat infertile couples when standard IVF techniques are not likely to be successful. ICSI is the process of injecting a single sperm cell directly into the egg; it is normally used when the male has a low sperm count or sperm motility is low and fertilisation is unlikely to occur naturally. This illustration shows the egg cell (ovum) being held at the end of a micropipette. The egg is surrounded by cumulus cells, which provide nutrients to the egg.
Credit: Maurizio De Angelis, Wellcome Images.

Human sperm sample: average count

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Light microscopy image of human sperm, showing a sample with average sperm count.
Credit: Dr Joyce Harper, UCL, Wellcome Images.

Human sperm sample: exceptional count

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Light microscopy image of human sperm, showing a sample with an exceptional sperm count.
Credit: Dr Joyce Harper, UCL, Wellcome Images.

Abnormal sperm

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Confocal microscopy image showing a variety of abnormal human sperm cells. Sperm with different types of head and tail defects surround a group of normal sperm in the centre.
Credit: Dr David Becker, Wellcome Images.

Sperm on the surface of an egg

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Scanning electron microscopy image of numerous sperm trying to fertilise a human egg. In order to successfully fertilise the egg they need to find their way through the tough zona pellucida, the membrane that surrounds and protects the egg.
Credit: Yorgos Nikas, Wellcome Images.

Seminiferous tubule

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Confocal microscopy image of a cross-section through a seminiferous tubule showing the developing sperm; they can be seen as a row of cells with their tails pointing into the lumen (opening) of the tubule. The nuclei are stained blue, and the mitochondria red. Sperm have a large number of mitochondria for energy to allow them to swim towards the egg.
Credit: MRC NIMR, Wellcome Images

Single sperm

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Digital artwork of a sperm, showing the head, midpiece and tail. The head of the sperm is surrounded by an acrosome ‘cap’ (blue), which contains enzymes that help the sperm penetrate the outer membrane of the egg to permit fertilisation. The midpiece contains large coiled a mitochondrion (gold) to provide energy to the tail, and two centrioloes (green), which are required for a viable embryo.
Credit: Anna Tanczos, Wellcome Images

Section of a testis

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Light microscopy image of a transverse cross-section through a testis. Staining of the tissue reveals the numerous seminiferous tubules - the location of sperm production. Between them are interstitial cells that support sperm production.
Credit: Spike Walker, Wellcome Images.