Cumulus cells and their extracellular matrix affect the quality of the spermatozoa penetrating the cumulus mass.

OBJECTIVE To investigate the role of the cumulus cells and the cumulus matrix in affecting the penetrability, morphology, acrosome reaction, and motility of human spermatozoa penetrating the cumulus oophorus. DESIGN Controlled experimental laboratory study. SETTING University gynecology unit. PATIENT(S) Women undergoing assisted reproduction treatment and men visiting the subfertility clinics. INTERVENTION(S) Human spermatozoa were allowed to penetrate through the cumulus oophorus and cell-depleted cumulus matrix in a capillary, and were treated with cumulus cell extract or hyaluronic acid. MAIN OUTCOME MEASURE(S) The morphology, acrosomal status, and motility of human spermatozoa were determined. RESULT(S) Fewer spermatozoa could penetrate the fresh cell-depleted matrix compared with intact cumulus oophorus. Spermatozoa that penetrated through the cumulus oophorus had higher percentages of normal morphology and acrosome reaction and had specific motility pattern. These effects were lost or reduced in the cell-depleted matrix that had been stored overnight. Hyaluronic acid, a main component of the cumulus matrix at concentration found in the cumulus oophorus, modulated sperm motility but did not affect spontaneous acrosome reaction. Cumulus cell extract did not affect sperm motility, but induced acrosome reaction. CONCLUSION(S) Both the cumulus matrix and the cumulus cells contribute to the effect of cumulus oophorus on spermatozoa penetrating through it.