The term serum refers to the fluid and solvent component of blood that does not play a role in clotting. It can be defined as blood plasma stripped of its clotting factors, or as blood with all cellular components and clotting factors removed. This fluid contains all proteins except those involved in blood clotting, encompassing electrolytes, antibodies, antigens, hormones, and any exogenous substances such as drugs or microorganisms.
The scientific study of serum is known as serology. Serum finds extensive application in numerous diagnostic tests and in blood typing procedures. The process of obtaining serum involves allowing a blood sample to clot, a process called coagulation.
In the realm of biopharmaceuticals, the serum from convalescent patients-those who are successfully recovering or have already recovered from an infectious disease-can be utilized in treating others afflicted with the same illness. This is due to the presence of antibodies generated during the patient's recovery, which act as potent agents against the pathogen.
A widely used variant is Fetal Bovine Serum (FBS), which is exceptionally rich in growth factors. It is frequently incorporated into growth media designed for the culture of eukaryotic cells. Similarly, vertebrate sera, such as FBS, and invertebrate hemolymph have historically served as essential sources of nutrients and growth factors for cultivating insect cell lines.
Blood serum and plasma are recognized as significant sources of biomarkers, valuable for both diagnostic and therapeutic purposes. However, their complex nature, characterized by a vast dynamic range, further complicated by the presence of lipids, salts, post-translational modifications, and various degradation mechanisms, presents considerable challenges in achieving analytical reproducibility, sensitivity, resolution, and assessing potential efficacy.
The Plural Form of Serum
Similar to many other mass nouns, the word serum has the capacity to be pluralized when used in specific contexts. The plural form commonly used is sera.
This pluralization is particularly relevant when discussing multiple distinct samples of serum, different types of sera, or when referring to serum in a general sense across various studies or applications.
Examples of Usage
- Researchers analyzed different sera from patients to identify specific antibodies.
- The laboratory requires various sera for a range of diagnostic tests.
- The study compared the efficacy of different sera in cell culture experiments.
While "serum" can be used as a mass noun, indicating an uncountable substance, the existence of the plural form "sera" acknowledges instances where multiple discrete units or types of serum are being considered.
Blood components
Etymological Considerations
The Latin word serum has conventionally been linked to the Greek word orós, which shares an identical meaning. Both have been compared to the Sanskrit verbal base sar-, purportedly meaning "flow" in Vedic texts. However, more recent linguistic scholarship has challenged this interpretation. The base sar- is now often read as "run off," supported by Vedic Sanskrit examples like ásarat ("ran off") and prasísarti ("lets run, stretches, extends"). These are not considered akin to sáraḥ ("lake, pond") and related words, which describe still water.
Further comparisons have been made between the Sanskrit etymon and the Greek verb hállomai ("I spring, hop") and the Latin verb salīre ("to jump," as seen in the English word "sally"). If these connections are accurate, the proposed Indo-European base is *sel-. In this scenario, any link between "serum," "orós," and the "flow" meaning becomes uncertain, leaving "serum" and "orós" without a definitive etymology.
