Reproductive cells in human

Present by: m.nafly(HND in Biomedical scientist)

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EGG CELL

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• The production of eggs in females begins before birth.

• Women are born with a specific and limited quantity of eggs. Usually one to two million.

• In humans, the egg cell is the largest cell.• It is visible to naked eye, it is about

0.1mm in size in humans.

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•It is produced in the OVARY and eventually released into the fallopian tube during OVULATION.

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•It is consist of protoplasm surrounded by a thin cell membrane.

•It may also have a noncellular covering called ZONAPELLUCIDA.

•Within the large nucleus with a nucleolusThe cell is haploid so that when a sperm cell fertilizes it, it forms a DIPLOID ZYGOTE.

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•The ovum is fertilized inside the female body, and the embryo then develops inside the uterus, receiving nutrition directly from the mother.

•The human egg cell grow from primitive germ cells that are embedded in the substance of the ovaries.

•Each of them divided repeatedly to give rise to several smaller cells, the OOGONIA.

•The oogonia develop into the ova, the PRIMARY OOCYTES.

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•It has many lysosomes (cortical granules).

•Lipid droplets for food reserved.

Structure of a secondary oocyte

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•Microvilli found all around the surface, they absorb nutrients from the follicle cells.•Zona pellucida, jelly like coat secreted by the granulosa cells.•It has first polar body.•Cytoplasm.•Nucleolus.•Nucleus.

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Adaptation of egg cells to its function.

•It has lots of cytoplasm, to support the many divisions that it undergoes and the second adaptation when a sperm cell interacts With it, the cell membrane changes immediately, to become impenetrable to any other sperm cells.

•Also it contains cytoplasm to survive on for the couple of hours it takes the egg cell to reach the womb.

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Adaptation of egg cells to its function.

•The egg cell is much bigger than the sperm and has a chemical around the out side to stop more sperm getting in.

•Egg is large to contain food store for embryo.

•It is haploid, has a single set of chromosomes. This ensures the uniqueness.

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Adaptation of egg cells to its function.

•Egg cell is thin enough to let the pointy headed sperm inside itself and with that it reproduces to create children.

•The egg can grown along with the baby and it can just feed the baby and look after the baby.

•The egg cell is also big round and it looks like a big bird nest.

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Coloured image of a 6 day old human implanting

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Human embryo and sperm

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No of sperm trying to fertilize an egg

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SPERM CELL

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Structure

•It is the male reproductive cell. •The sperm cell has a head a body and a tail.•The head contains the 23 chromosomes. •The body contains mitochondria.•The tail is what enables it to swim up the females cervix and fallopian tube(s) to her egg.

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Lifespan

•Sperm swim in and are nourished in the semen. •Once inside the fallopian tube(s) they have a life span of about 5 days.•This means they can be in the fallopian tube for 5 days in advance of ovulation and still fertilize the egg. The egg, unfertilized, has a life span of only about 24 hours.•In the vagina, they die in only a few hours.•In the open air, they die rapidly.* Nafly Hussain*

Temperature Requirements

•To develop, they need a temperature of about 3-5 degrees (Fahrenheit) below the rest of the body. •That is why the testicles hang (in the scrotum) outside the body.•The scrotum has a built in thermostat.

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Motility and Pregnancy

•Once inside the woman, they swim from the vagina, to the cervix, to the fallopian tubes. •The egg is fertilized in the fallopian tubes.•If they don't make it to the egg, there is no fertilization and no baby.* Nafly Hussain*

Chromosomes

Unlike every cell of the male body, which has 46 chromosomes (in 23 pairs), these cells have only 23 (not in pairs). The same is true for the female eggs.When a sperm and an egg combine they once again form a perfect cell with 46 chromosomes in 23 pairs. This one cell now has all the information (DNA) necessary to produce a complete human being. The combined DNA now has all the information of the physical characteristics of both parents.* Nafly Hussain*

Adaptation of sperm cells to its function.

• A sperm cell has a long tail to help it swim to the egg.• mid- piece which contains large amount of mitochondria to release energy needed to make the tail move.• The head of the sperm also contain enzymes to break down and digest the zona pellucida of the egg so that it can fertilize it. * Nafly Hussain*

Adaptation of sperm cells to its function.

• They also have a pointed front end so they are able to penetrate the egg.

• The also have half genetic information inside them so that they can swim to the egg and complete the full genetic information which makes the baby.

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END

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