Articles: Singular vs. Plural

Articles (a, an, the) are adjectives that modify nouns. If they are used incorrectly the reader can be left wondering if you are referring to a specific thing or to a non-specific item or category. Worse, they could interpret the text incorrectly and make a wrong assumption. Incorrect use of articles can also lead to confusion relating to singular vs. plural senses.

Which article?

The word “the” should be used in conjunction with a noun referring to a particular item or group of items (it can be used with both plural and singular nouns). For example, “the sections were then stained with H&E” implies that the sections you had referred to in recent sentences were stained. By contrast, “a” should be used in conjunction with non-specific nouns. For example, “a section was then stained” infers that a single section, any section, was stained. “A” should only be used to refer to a single item or category, and should not be used in conjunction with plural nouns. So saying “a sections” would be incorrect.

Asian authors frequently leave articles out of sentences making them sound awkward and unnatural, which would be the case when omitting the “the” in “adenovirus was injected into the fourth ventricle.”


  • “The antibody was injected into the hippocampus…” (articles required to specify a particular antibody, presumably already referred to in the text, and a specific hippocampus, belonging to a subject already described).
  • “A new method of extraction was devised…” (“a” used rather than “the” because this statement introduces this method to the reader, therefore it is non-specific at that time. Once introduced to the reader, “the new method of extraction” should be used to refer to that method in the specific sense).

Singular or plural?

Nouns are used in the plural sense by adding an “s” to the end (in most cases). In the absence of an article, it can sometimes be unclear if the wrong sense (plural vs. singular) has been used. For example, in the sentence “Acetyl group was added,” the reader is not clear whether the author means “An acetyl group was added,” or perhaps “Acetyl groups were added.”

Thus, when referring to multiple items, the plural sense should be used to avoid potential confusion. This is commonly forgotten when describing figures (use “arrowheads” rather than “arrowhead” where there is more than one in the figure; likewise, use “solid bars” rather than “solid bar” when referring to a bar chart with multiple bars).


  • “A biopsy was obtained…” (describing a single biopsy).
  • “Biopsies were obtained from eight patients…” (no article necessary unless these biopsies had already been introduced to the reader, in which case they would need to be referred to in the specific sense “The biopsies were obtained…”).