Ly49 knockdown in mice results in aberrant uterine crypt formation and impaired blastocyst implantation

• The role of the Ly49 family of receptors in implantation is investigated.
• Knockdown of Ly49 in mice resulted in aberrant crypt formation.
• Knockdown of Ly49 in mice affected blastocyst implantation.
• Ly49 expressed by non-lymphoid leukocytes is important for implantation.

Genetic knockdown (KD) of the mouse Ly49 receptor family is reported to result in infertility despite the presence of zona-enclosed blastocysts in the uterus. Ly49 receptors regulate leukocyte functions particularly Natural Killer (NK) cell functions and are analogous to human killer immunoglobulin-like receptors (KIRs). Histological analyses of gd3.5–4.5 B6.Ly49KD uteri identified hatched but retarded blastocysts with pyknotic nuclei, aberrant endometrial crypt formation and impaired uterine lumen closure accompanied by a lack of primary decidualization These data support peri-implantation roles for leukocytes expressing the Ly49 receptor repertoire and may give insight into KIR-based regulation of human infertility.