Cytoplasmic droplets: the good, the bad or just confusing?

Area of Science:

• Reproductive Biology
• Spermatogenesis Research
• Veterinary Andrology

Background:

• The term "cytoplasmic droplets" is ambiguously used by basic scientists and clinicians.
• Existing literature lacks consistent terminology regarding cytoplasmic droplets and their association with sperm function and infertility.
• This ambiguity hinders clear communication and accurate interpretation of research findings in animal reproduction.

Purpose of the Study:

• To review the literature on cytoplasmic droplets in animal sperm, focusing on their presence, position, and loss.
• To propose a standardized terminology for structures previously referred to as cytoplasmic droplets.
• To differentiate between normal and abnormal cytoplasmic residues in sperm to improve understanding of infertility.

Main Methods:

• Comprehensive literature review of scientific articles and clinical reports on cytoplasmic droplets in animal sperm.
• Analysis of the presence, location, and implications of cytoplasmic droplets in relation to spermatogenesis and sperm quality.
• Synthesis of findings to identify inconsistencies in current terminology.

Main Results:

• Cytoplasmic droplets are associated with both normal, functional sperm and abnormal, dysfunctional sperm.
• The presence and characteristics of these droplets differ significantly based on the quality of spermatogenesis.
• Current terminology fails to distinguish between these two distinct entities.

Conclusions:

• A clear distinction is needed in the terminology used for sperm cytoplasmic residues.
• Proposed terms: "cytoplasmic droplet" for normal, functional sperm and "excess residual cytoplasm" for abnormal, dysfunctional sperm.
• Adopting this new terminology will enhance clarity in research and clinical practice concerning male infertility in animals.