Human cumulus cell complexes studied in vitro by light microscopy and scanning electron microscopy

Abstract

SummaryVarious researchers describe the morphology of cumulus cells (CC) in vitro, but few have investigated their behaviour on plastic. Knowledge concerning the behaviour of human CC could be useful in improving the success of in vitro fertilisation procedures. This study aimed to describe the morphology and behaviour of CC in vitro and to investigate movement on a collagen-coated substrate. Following collection some cumulus were mechanically dissected from those surrounding the oocyte. Cumulus aggregates were cultured over 24 h using Earle's medium supplemented with 8% albumin. Substrata were plastic coverslips coated with collagens I, IV, or mixed collagens. Cumulus cultured over corresponding time periods on uncoated coverslips served as controls. Specimens were fixed and prepared for scanning electron microscopy. Over 24 h the controls began exhibiting the morphological features associated with cell movement: cell surface protrusions changed from blebs to microridges, lamellipodia and leading lamellae; cell shape altered from rounded and upright, to flattened. Extracellularmatrix (ECM) transformed from a thick, sheet-like substance to a thin, fibrous material. By 24 h, cells contacting ECM remained rounded showing few features of movement. Collagens enhanced attachment of CC as a monolayer on the substrate. Cell morphology varied according to the collagen type used. On mixed collagens, cells attached rapidly, appearing to be predominantly non-motile. On collagen type I there was less attachment of cells but increased motility. On collagen type IV there was decreased attachment and the cells remained spherical. In conclusion, collagens enhance the settling of cumulus cells on a plastic substrate and the cells exhibit some specificity in attaching to collagens.

Expression of Hyaluronan Synthases and Corresponding Hyaluronan Receptors Is Differentially Regulated During Oocyte Maturation in Cattle1

“…Although RHAMM was unregulated under gonadotropins, possible functions of this HA receptor in the bovine reproductive tract could be important, because basic expression levels during IVM were found to be compared to CD44 expression. The RHAMM may mediate movement and attachment of human cumulus cells [46], or it could modulate ciliary beating of oviduct epithelia, as described for the respiratory system [30]. Recent work discovered CD44 as the essential HA receptor throughout development of the preimplantation human embryo [47] and during trophoblast implantation [48].…”