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The 4 types of sex cells

The 4 types of sex cells

March 28, 2024

Human beings, like most other animals, are multicellular organisms that perpetuate our species through the type of reproduction we know as sexual. This type of reproduction, which results in the emergence of individuals with genetic characteristics from two individuals, something that gives species a much greater variability than that offered by asexual reproduction.

For sexual reproduction to produce a new being, it will be necessary for a certain cell type to merge: Sex cells or gametes . It is about these that we are going to talk about in this article.

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The gametes or sex cells

They are called gametes or sex cells to a certain type of cell which Its main function is to generate a new being , perpetuating the species and the genes of the parents.


Sex cells have different forms, specifically finding two types whose union will be generated by the zygote from which a new individual will eventually develop. The specific name of these cells depends on the type of living being that we are talking about, existing a masculine and a feminine one.

This type of cells has half of chromosomes of which the species in question has , something that when the new being appears before the union or fusion of two cells of two different individuals allows the child organism to end up having the same number of chromosomes as its parents, although with a genetic information different from any of the previous ones. After their union, there is a genetic recombination of the genetic information from both cells, generating a unique genetic code through said recombination.


In the case of the human being, we have a total of 46 chromosomes divided into 23 pairs. Of these, 22 of the pairs correspond to somatic chromosomes and are the same regardless of sex. But nevertheless par 23 differs between men and women , these being the sex chromosomes that mark our genetic sex. Specifically, the male has an X and a Y chromosome, while the woman has two X chromosomes.

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Sex cells in animals

When we talk about sex or sexual cells, the first thing we think is the type of reproduction and cells that we humans have and that also have the rest of animal species: sperm and ovules.

The sperm

Denominated sperm to the sex cells of the male gender, and which possess half of the genetic information necessary to train a new living being. It is a type of cell of very small size, inferior to that of female gametes, and that are formed in great quantity within the testicles of the males of each species.


For fertilization to occur it is necessary that the sperm travel to the egg, of which only one (usually, although there are exceptions) will get into the egg and combine its genetic material with it. That is why the sperm has morphological adaptations that allow this displacement.

Its basic morphology is the following:

First we can observe the existence of a large head (the largest part of the sperm) within which we can find the nucleus , in which the genetic information in question can be found, and the acrosome or layer formed by various enzymes that allow it to allow the sperm to enter the female gametes. In addition to this we can find different substances that allow to nourish and allow the movement of the sperm.

The other main part is the tail or flagellum, thanks to which sperm can move through the female body to reach the egg. Inside it we can find first a small neck through which it joins the head, later an intermediate piece in which we can find different mitochondria , which allow to produce enough energy (through the substances present both in the sperm itself and in the rest of the semen) and finally the flagellum or final part, which moves to allow displacement.

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The ovules

The ovules are the female sex cells, which carry half of the genetic information necessary for the genesis of a new being. It is a type of large cell, which have the shape of a sphere and which are produced by the ovaries of the females of the different species .

The ovules present the characteristic that they are not always available for fertilization, there is a whole cycle through which an ovule is produced, mature, remains available for possible reproduction and is released if not fertilized, this being the menstrual cycle. It generates approximately one a month (actually, it's usually 28 days).

Also, unlike sperm that are present in large numbers throughout life, there is only a certain number of them in each female. During the reproduction itself the ovum remains motionless, until the sperm reach it and finally join to penetrate it (if it is achieved).

The structure of this cell is as follows, from inside to outside:

First and inside, highlights the nucleus in which is the genetic information that would allow the formation of a new being to join a sperm. We can also find vitelium inside , a series of substances as an energy reservoir that would allow the survival of the zygote until the formation of a placenta. All this would be surrounded by a plasma membrane that limits the cell and through which chemical elements can enter and exit, allowing its interior to be chemically balanced.

Around the membrane we can find a protective gelatinous layer, called the pellucid layer , which acts as protection while allowing the entry of a first sperm and ends up hardening to prevent more than one from entering. A last layer, the outer one, is the corona radiata. This will have special relevance in regulating sex hormones and generating the placenta if there is fertilization.

Sex cells in vegetables

Spermatozoa and ovules are not the only types of sex cells that exist, being only those of animals. Plants and other plants also have sexual reproduction in many cases , being its sexual cells the oosphere and the pollen.

The oosphere

It receives the name of oósfera to the type of feminine sexual cell of the plants that have the capacity to reproduce sexually. This type of cell can be found inside the so-called seminal rudiments located in the embryonic sacs of the plants, located in the flowers.

Like the animal ovules, it owns half of chromosomes that the rest of cells of the progenitor individuals. The pollen or male gamete at vegetable level comes into contact with it through the stigma of flowers.

The pollen

Pollen would be the vegetable equivalent of sperm: the male sex cell of plants. These are small particles in the form of grains that are formed in the stamens of plants. It joins the oosphere in the process known as pollination (for which they need the wind or the help of animals.

These grains, whose content is half of the genetic information necessary to produce a new being, enter into the stigma and join the oosphere. For this, once in the stigma, pollen generates a small prolongation called a pollen tube in order to transport its genetic material to the oosphere.


Meiosis: Where the Sex Starts - Crash Course Biology #13 (March 2024).


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