Sperm Phenotyping

Functional sperm are produced through a complicated process within the testes called spermatogenesis and progress to the epididymis where the gametes mature and are stored until ejaculation. A breakdown at any one of these stages can lead to male infertility or subfertility. The production of mutant mouse models often yields unexpected male infertility or subfertility phenotypes. Our mouse sperm phenotyping services can help you identify, characterize, and define the male infertility and subfertility phenotypes caused by genetic modification. Publication quality images and professional reports will also be provided for requested sperm phenotyping services.

Sperm Motility and Morphology Assessments

Computer assisted sperm analysis for assessments of cauda epididymal sperm count, total motility (% of motile sperm), rapid motility (% of motile sperm with VAP ≥10 µm/s), and progressive motility (% of motile sperm with VAP ≥ 50 µm/s and STR ≥50%) at 37 °C. VAP = Average cell path velocity in µm/s; VSL = Straight line velocity in µm/s; STR: The Straightness ratio of VSL/VAP, expressed as a percent. Sperm morphology are assessed manually and % of sperm with abnormal heads, % of sperm with abnormal tails and digital sperm pictures of different abnormal types are obtained. Each service will assess sperm from 3 mutant male mice of a mouse line and sperm from 3 wildtype male mice on the same genetic background as a control.

Sperm Count and Production Measurement

Measuring epididymal sperm count and daily sperm production in testes are quite important criterions in reproduction. Epididymides are weighted individually, and testes are decapsulated and weighted individually. Then epididymal sperm count and the count of testicular sperm and spermatids are obtained after tissue homogenizations. The values for the number of sperm and spermatid heads per testis and per g testis are divided by 4.84, respectively, to obtain the daily sperm production (per testis) and efficiency of sperm production (per gram testis). Each service will assess sperm from 3 mutant male mice of a mouse line and sperm from 3 wildtype male mice on the same genetic background as a control.

Sperm in vitro fertility assessment

For the purpose to identify the causes of male factor infertility, four types of in vitro fertilization (IVF) methods including conventional IVF using wildtype sperm, conventional IVF using mutant sperm, cumulus-free IVF (cumulus layer is removed from each oocyte), and laser-zona-drilling (LZD)-assisted IVF are performed and compared side by side to determine if sperm fertilization defect, cumulus-penetration defect or zona-penetration defect are present. Embryos from each of the IVF procedures will be cultured in vitro for 4 days to obtain blastocyst formation rate. Each type of the IVF procedures will be repeated 3 times using 3 wildtype males, 3 mutant males, and up to 4 x 3 x 10 = 120 wildtype females as egg donors, and therefore total 3×4 = 12 IVF procedures will be performed.

To learn more about our Mouse Sperm Phenotyping Services or how to start your project today contact us at: mbp@ucdavis.edu.

Sperm DNA Fragmentation Assessment

Sperm DNA integrity is essential for embryo development, although sperm with minimal DNA damage retain fertilizing ability. Mouse sperm DNA fragmentation index (DFI) will be obtained by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-nick end labeling (TUNEL) assay. Total 6 male mice are analyzed per service (3 mutant males and 3 wildtype males as control), and a minimum of 200 sperm per male from at least 5 fields will be analyzed at 1000× magnification under a Nikon Eclipse Ci-FL fluorescence microscope.


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Li MW, and Lloyd KCK et al. Safety, efficacy and efficiency of laser-assisted IVF in subfertile mutant mouse strains. Reproduction 2013; 145: 245-54.

Li MW and Lloyd KCK et al. (2014) IVF recovery of mutant mouse lines using sperm cryopreserved with MTG in cryovials. CryoLetters 2014; CryoLetters 35:145-153.