Human oocyte-cumulus complexes stimulate the human acrosome reaction

Abstract

Oocyte-cumulus complexes were obtained, after induced ovulation, from infertile patients participating in an in-vitro fertilization programme. About 6 h after retrieval and depending on the expansion of the cumulus, 100,000 motile spermatozoa, prepared by a migration-centrifugation method, were added. After 14-18 h incubation at 37 degrees C, oocytes were examined for signs of fertilization (pronuclei and polar body formation) and then removed; spermatozoa remaining in the incubation medium were fixed for transmission electron microscopy. To provide an adequate number of cells for observation, spermatozoa from a minimum of 3-5 oocytes from the same patient were pooled. When sufficient spermatozoa were available after insemination, the remainder of the suspension was incubated at 37 degrees C and fixed along with the corresponding oocyte-incubated sample. In all, 32 sperm samples were assessed and fertilized oocytes were obtained with 29 of these. In the 24 samples in which greater than 100 spermatozoa (mean of 192) could be assessed, 32% of spermatozoa had initiated or completed the acrosome reaction. In the 15 of these 24 samples for which oocyte-free controls were available, 31% of cells were reacting or reacted, compared with 15% of cells (P less than 0.001) in the controls. In the remaining 8 samples, incubated with oocyte-cumulus complexes, less than 100 but greater than or equal to 20 spermatozoa (mean of 42) were assessed and again 32% of spermatozoa were reacted.(ABSTRACT TRUNCATED AT 250 WORDS)

Inter-α-Inhibitor Binding to Hyaluronan in the Cumulus Extracellular Matrix Is Required for Optimal Ovulation and Development of Mouse Oocytes1

“…Additionally, the viscoelastic properties of the cumulus mass apparently aid in protecting the oocyte from the mechanical stress produced by the process of extrusion. The results of these and other studies support the possibility that the presence of an intact and successfully expanded cumulus mass aids in oocyte maturation, optimal ovulation and fertilizability [26], oocyte transport to the oviduct [33], the zona reaction [34], sperm motility [35][36][37], sperm attraction [38], sperm selection [39,40], and the acrosome reaction [41].…”

“…It has been established here and in previous studies that an intact cumulus mass protects developing oocytes before and after fertilization [25,26,[33][34][35][36][37][38][39][40][41]. For example, Sato et al [48] demonstrated that cumulus-produced component(s) (i.e., glycosaminoglycans) delay the degenerative process during in vitro oocyte culturing.…”

Redistribution of the intra-acrosomal EGFP before acrosomal exocytosis in mouse spermatozoa

“…Another unresolved question concerns the real inducer(s) of the AR in fertilizing spermatozoa in vivo. Although the cumulus oophorus surrounding oocytes has been implicated as the site of the AR in some mammalian species such as human (Stock et al , 1989) and shrew (Kaneko et al , 2001) there is no unequivocal evidence to support this view in mouse. In a previous work from our group using in vitro fertilization (IVF), we observed that the AR, as shown by a loss of EGFP fluorescence in the acrosome, rarely begins while spermatozoa are traveling through the cumulus (Hirohashi et al , 2011).…”

Further indications of the multicomponent nature of the acrosome reaction‐inducing substance of human follicular fluid

“…In addition to the zona pellucida (Cross et al, 1988) and cumulus oophorus (Siiteri et al, 1988a;Stock et al, 1989), various components of follicular fluid from several mammalian species have been discussed as possible initiators of the AR in vitro (Meizel, 1985).…”