The English language has always been a promiscuous borrower of words from other languages, and for scientific writing Latin has been one of the most common sources.
Currently, as a standard publishing style, when words that belong to another language are used, they are italicized for clarity. However, with the extensive usage of Latin terms in scientific writing, many style guides and journals now do not insist on Latin terms being italicized in academic articles.
For example, the ACS style guide states that common Latin terms and abbreviations such as ab initio, et al, in situ, in vitro, and in vivo should not be italicized; however, italicization should be used when referring to genus, species, subspecies, and genotypes. The term Streptococcus pneumoniae should be italicized because it is a name of the organism that is a member of the genus Streptococcus and not because the word is derived from Latin.
In fact, in academic usage, italicized terms are generally understood to be scientific convention and not related to a style.
Unfortunately, many journals and publishers are inconsistent in their usage of italicization, e.g., in its Instructions to Authors, the Journal of Electron Microscopy (yes, periodical titles are italicized) does not address the usage of italics in their formatting guidelines.
However, for in-text citations, they insist on the usage of “et al.” for references with more than three authors. Although this many seem to be a minor issue, many first-time authors would have to deal with this when they are creating the initial drafts of the article that they would be submitting.
We suggest that first-time authors should refer to the previous papers of the journal to which they are submitting to make themselves aware of the predominant style and usage. Also, referring to standard style guides such as AMA, CMOS, ACS, and MLA would definitely help when you are working on your initial papers that would be submitted for publication.
This makes the overall process of submission and publication easier for both the author and the journal.