Learn something new every day
More Info... by email
Glandular epithelium is the membranous tissue made up of cells that covers all the glands in the body. The main function of glandular epithelium is the secretion of fluids into ducts or fluids of the body. Secretion types depend on the location and function of the gland.
Epithelium is a tissue that is made up of different types of cells. It forms the inner lining of body cavities and hollow organs, and it covers the body and organs as well. Epithelial tissue is also referred to as avascular tissue because it has no direct supply of blood. Due to the fact that it covers the whole body and lines organs, the epithelium always has a surface that is either exposed externally, as in skin, or internally to an organ, such as the large intestine, or another open space.
The types of cells that make up epithelium are quite varied. They are classified by how thick they are and their shape. Generally speaking, epithelium cells are tightly packed together and have no space, or very little space, between them. Glandular epithelium has a variety of cells types in its structure, but they are usually columnar or cuboidal in shape.
Functions of the glandular epithelium depend on the type of gland that it covers. There are two types of glands, endocrine and exocrine. Endocrine glands secrete into tissue fluid or blood, such as the thyroid gland. Exocrine glands secrete through ducts onto surfaces, such as the sebaceous glands of the skin, or the glands of the digestive tract lining.
In addition to types of glands, there are also different types of secretion methods that glandular epithelium cells utilize. The exocrine glands have several methods. Most exocrine cells are merocrine glands, which means they release their fluids through exocytosis, a process of guided secretion through the cell. Exocrine cells also secrete by means of partially releasing part of the cells, which happens in apocrine glands, or by totally destroying itself to become part of the fluid, which is the case in a holocrine gland.
Merocrine cells are either serous or mucous. Serous cells release a watery, enzyme filled fluid called serous fluid. Mucuos cells produce mucus, which is a protective fluid.
Glandular epithelium has numerous and complex functions in the body. It is a vital part of the digestive, protective, and hormonal systems. Often times, problems in the glandular epithelium are the source of problems with an organ or gland.
@pleonasm - Really, glandular epithelial tissue is all the same kind of cell, just performing different functions.
So you could just as easily compare milk glands to saliva glands or the glands which secrete hormones.
I think that people just become slightly desensitized to biological functions because they don't really witness any but their own in modern life, and those are considered to be "gross".
We try our hardest not to be seen sweating, or shiny from oil, or whatever.
So it's unsurprising that a comparison between milk glands and sweat glands might make people uncomfortable, because glands in general make people uncomfortable.
@croydon - It's not really something you need to think too hard about unless you are an endocrinologist.
I mean, just because something is a "modified" version of something else doesn't really make much difference in the long run. Nature tends to appropriate things all the time. The nose of the Rhino is made out of hair, when you get right down to it, but it serves a very different purpose now.
And, besides, I've heard that it's still quite controversial to say the mammary glands are made from sweat or sebaceous epithelial cells.
They don't really know which came first, after all, or if one developed separately from the others, or what. It's all just speculation.
I have always found it kind of bizarre and a little bit icky that milk glands are really just modified sweat glands. It's bad enough thinking of this in humans, but really it applies to all mammals, so cows' milk is made from the same thing.
It doesn't make me not want to drink milk but I just try not to think about it too hard.
Really, when you think about milk too hard though, and where it comes from, it seems like a very strange thing for human beings to be drinking in the first place.
But then, drawing sustenance from another animal without killing it is actually a really cool thing to do. So, I suppose it depends on how you think about it.
One of our editors will review your suggestion and make changes if warranted. Note that depending on the number of suggestions we receive, this can take anywhere from a few hours to a few days. Thank you for helping to improve wiseGEEK!