Morphology comparison of individually selected hyperactivated and non-hyperactivated human spermatozoa

Area of Science:

• Reproductive Biology
• Sperm Motility Analysis
• Human Gamete Morphology

Background:

• Sperm hyperactivation is crucial for fertilization, involving characteristic motility patterns.
• Understanding the morphology of hyperactivated sperm is important for assessing male fertility.
• Previous studies have not specifically isolated and analyzed the morphology of live, hyperactivated human sperm.

Purpose of the Study:

• To compare the morphology of in vitro hyperactivated human spermatozoa with non-hyperactivated (non-hyp) spermatozoa.
• To determine if hyperactivated sperm selected in vitro exhibit distinct morphological characteristics.
• To investigate the morphological profile of a homogeneous population of live, hyperactivated human sperm.

Main Methods:

• Utilized the Hobson Sperm Tracker (HST) with specialized software to define and identify hyperactivated sperm based on velocity and displacement parameters.
• Employed micromanipulation with a fine needle to isolate individual hyperactivated sperm from patient ejaculates.
• Conducted detailed morphological analysis on isolated hyperactivated sperm and non-hyperactivated sperm from 56 patient samples.

Main Results:

• Hyperactivated spermatozoa showed a significantly higher percentage of normal head morphology (P < 0.0001) and small acrosomes (P < 0.0001).
• Compared to non-hyperactivated sperm, hyperactivated sperm had significantly fewer defects in head shape (large/round), midpiece, and tail (P values ranging from 0.002 to < 0.0001).
• Demonstrated that a selected population of live, hyperactivated human sperm is predominantly composed of cells with normal morphology.

Conclusions:

• Live human spermatozoa selected for in vitro hyperactivated motility exhibit significantly superior morphology.
• This finding holds true even in patients with varying degrees of teratozoospermia (poor sperm morphology).
• Morphological normality is a key characteristic of the hyperactivated sperm population crucial for successful fertilization.