Sebum appears as a result of the formation of sebaceous glands which comes in contact with the grease that seeps out from the hair follicle to fill the cells up. The moment the follicle has been completely filled up, the sebum will be spread all over the surface of the skin, resulting in an oily face. As long as the procedure works as how it normally does, the skin will be oiled properly and remain healthy. However, if it fails to work out as planned, it might result in the skin becoming too dry or oily, and overly oily skin will allow acne to form.

As the skin cells or corneocytes are treated while they are stored in the pore instead of coming out to make sure the skin does not become too oily unnecessarily. The majority of skin cells only form right at the surface of the pore and not around the bottom part area.

There is an increased level of sebum being produced.

Once it reaches this stage, the external part of the pore looks particularly normal. However, there are some distinct differences in the cells right around the pore which might be seeable or not. The fluid inside the pore will start to build up, creating a bottleneck which stops peeling off. In medical terms, this stage is known as microcomedone.

Bacterium Propionibacterium acnes, also known as P. acnes, can be located inside the pores. It uses sebum as nutrients to grow. With an increased level of sebum produced, the number of P.acnes bacteria found in the pore also starts increasing. In the microcomedone stage, the following bacteria do not result in any kind of infection as they are the sole substance found in the pore which under no circumstances, cause any infection to the skin.

In the sebaceous gland and shredded skin cells called corneocytes will create a thick and solid substance. A closed comedone, also called a whitehead (as it consists of a white substance) appears when the hole of the pore is narrow or closed.

Once the sebaceous beings building up, the cells near the pore will start to swell. Whitehead may either be uninfected or infected as it really depends if the other cells all around the pore will be infected by the P.acnes bacteria.

The cells around the pore will start to become swollen when the sebaceous substance builds up. Blackheads may either be uninfected or infected depending on whether the other cells surrounding the pore will be affected by the P.acnes.

Corneocytes are sebum from dry skin cells and the sebaceous gland, they change and form a solid and thick substance. Once the hole of the pore is exposed to the air and opened up, it becomes an open comedone, also known as blackhead (as it comprises of black substance)

The dry skin cells and sebaceous glands produce sebum which is also called corneocytes. They build up and apply pressure on the cells around the pore.

With enough force applied, the pore will split up and the sebaceous liquid will spill all around the skin. Moreover, as the sebaceous substance contains plenty of P.acne bacteria, the skin surrounding the pore will get infected and a red bump, also known as a typical pimple will form. Medically, it is more properly known as an inflammatory papule.

A pimple and a pustule are two separate things as a pustule has white blood cells in it. The immune system fights off the P.acne infection, and at certain points, the white blood cells which are part of the immune system will multiply and create pus (also known as a pustule) in the pore.

We are aware of what part of the immune system form pustules and pimples, but are unsure of the actual reason why these certain pimples or pustules contain pus in them while why some others don’t contain it. It can only be looked at from a scientific approach as both pimples and pustules are treated in the same manner.

In most cases when the bacteria or sebaceous substance begins to flow onto the surrounding the skin, the infection will start to spread much deeper and wider, resulting in scars and the formation of cysts or nodules. These are the kinds of deep acne which can become very aching and has no reaction to over-the-counter methods or treatments.