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An investigation of excess residual cytoplasm in human spermatozoa and its distinction from the cytoplasmic droplet

Anil K Rengan1, Ashok Agarwal1, Michelle van der Linde2 and Stefan S du Plessis2*

Author Affiliations

1 Center for Reproductive Medicine, Glickman Urological and Kidney Institute, Cleveland Clinic Foundation, Cleveland, Ohio, 44195, USA

2 Medical Physiology, Faculty of Medicine and Health Sciences, Stellenbosch University, Francie van Zijl Avenue, Tygerberg, 7507, South Africa

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Reproductive Biology and Endocrinology 2012, 10:92  doi:10.1186/1477-7827-10-92

Published: 17 November 2012


Recent studies have shown cytoplasmic droplets to be normal morphological occurrences in human male spermatozoa. When the cytoplasm around the sperm midpiece is present in large amounts, however, pathological effects may transpire. The cytoplasmic droplet then becomes known as excess residual cytoplasm, which can impair overall sperm function and produce higher levels of reactive oxygen species, potentially leading to male infertility. Though the distinction between cytoplasmic droplets and excess residual cytoplasm has been made, some studies fail to recognize the difference and incorrectly label the latter as a cytoplasmic droplet. This review attempts to clarify excess residual cytoplasm’s effect on fertility, examine the enzymes responsible, and suggest tests and possible treatment options for those affected by this defect.

Cytoplasmic droplet; Excess residual cytoplasm; Midpiece; Spermiogenesis; Cytoplasmic extrusion; Residual body; Regulatory volume decrease; Reactive oxygen species; Oxidative stress; Peroxidative damage