Dictionary > Pinealocyte


noun, plural: pinealocytes
The major cell type component of the pineal gland, and is involved in the production of melatonin
The pineal gland is a small endocrine gland. It resembles a pinecone in terms of shape (thus, the name). In humans, it is reddish-gray in color and about 5 to 8 mm in size. It is comprised mainly of pinealocytes, neuronal-like peptidergic cells, pineal neurons, perivascular phagocytes, and interstitial cells. The pinealocyte is a cell body with 4 to 6 processes. Its main function is to secrete melatonin. Melatonin is a hormone involved in the regulation of biorhythms, colour changes in the skin of reptiles, and reproductive cycles in mammals.
There are two types of pinealocytes: (1) type 1 pinealocytes and (2) type 2 pinealocytes. The type 1 pinealocytes (also called as light pinealocytes) are round or oval in shape. Their diameter ranges from 7 to 11 μm. They are typically more numerous in number and also the more active than type 2. The type 2 pinealocytes (also called as dark pinealocytes) appear round, oval, or elongated. Their diameter is about 7 to 11.2 μm. 1
Histologically, the pinealocytes are stained using silver impregnation techniques. They would appear as cells with elongated and branched cytoplasmic processes. The type 1 pinealocytes appear light whereas the type 2 appear dark under a light microscope.
See also:


1 Al-Hussain, S. M (2006). “The Pinealocytes of the Human Pineal Gland: A Light and Electron Microscopic Study”. Folia Morphologica. 65 (3): 181–87.

You will also like...

Origins of Life on Earth
Origins of Life on Earth

Earth was created around 4.5 billion years ago and life began not long after. Primitive life likely possessed the elemen..

The Human Physiology
The Human Physiology

Physiology is the study of how living organisms function. Thus, human physiology deals specifically with the physiologic..

Buttress roots

This study guide tackles plant roots in greater detail. It delves into the development of plant roots, the root structur..

Water in Plants

The movement of molecules (specifically, water and solutes) is vital to the understanding of plant processes. This tuto..

Protein (illustration)
Protein Variety

The sequence of amino acids determines the type of protein. Protein is synthesized according to the sequence of nucleoti..

Cambial cells
Plant Tissues

Plant organs are comprised of tissues working together for a common function. The different types of plant tissues are m..