ISOLECITHAL Meaning and
Definition
-
Isolecithal is an adjective used in biology to describe a type of egg or cytoplasmic organization found in certain organisms, particularly in the animal kingdom. It refers to the distribution or arrangement of yolk within the egg or the cell. In isolecithal eggs, the yolk is evenly distributed throughout the cytoplasm, resulting in a homogeneous distribution of nutrients. The term "isolecithal" is derived from the Greek words "isos," meaning equal, and "lekythos," meaning yolk.
This type of yolk distribution can be observed in many primitive organisms such as certain types of invertebrates, like sponges, cnidarians (e.g., jellyfish), and flatworms. Fishes also have isolecithal eggs, but with larger amounts of yolk. In isolecithal eggs, the even distribution of yolk allows for a more uniform development of the embryo, as the nutrients are readily available throughout the cytoplasm.
Compared to other types of yolk distribution patterns, such as telolecithal (localized yolk) or centrolecithal (central yolk), isolecithal eggs are generally considered less specialized. They often result in smaller eggs with limited yolk reserves. This is in contrast to telolecithal eggs, which are commonly found in birds and reptiles and have a well-defined concentration of yolk at one pole, allowing for prolonged embryonic development. Overall, isolecithal refers to a specific type of yolk distribution in eggs that plays a crucial role in the development and growth of certain organisms.
Etymology of ISOLECITHAL
The term "isolecithal" is derived from two roots: "iso-" and "lecyth".
The prefix "iso-" comes from the Greek word "ísos", meaning "equal" or "same". It is commonly used in scientific terminology to indicate equality or similarity.
The second part, "lecyth", is derived from the Greek word "lékuthion", which means "yolk" or "egg yolk". It is often used in reference to the yolk of an egg or the storage of nutrients in an egg.
Therefore, when combined, "isolecithal" refers to the condition where the yolk is uniformly distributed throughout the cytoplasm of an egg cell, without any concentration at one particular end. This term is commonly used in the field of embryology to describe certain types of egg development.
