Sperm Pairing in the Gray Short-tailed Opossum, Monodelphis domestica

In this study, I investigate the mechanism of sperm pairing in the gray short-tailed opossum, Monodelphis domestica. During maturation in the epididymis, M. domestica spermatozoa pair up, adhering at their acrosomal faces. Paired spermatozoa traverse the female reproductive tract, unpairing just before fertilization. I hypothesize that extramembranous sugar residues mediate pairing, and that sperm unpair in crypts in the oviductal isthmus. I examine reproductive tissues histologically to identify when and where sperm unpair. My results suggest that unpairing occurs in the oviductal crypts, and that N-acetyl-galactosamine residues may play a role in sperm adhesion