There are several different mother/daughter relationship facets occuring in Sylvia Plath's Bell Jar. I will briefly reference each of the facets and then dive into the implications for Esther and how this is significant.
First, the actual relationship between Esther and her mother has very little attention.
Secondly, Esther looks for a mother in other places, primarily in Dr. Nolan and Jay Cee (especially here).
Third, Jay Cee is initially taken with Esther, seeing a lot of talent in the girl, however Jay Cee has a lot of ambition and criticizes Esther for not having much ambition.
The significance lies in Esther. Through a combination of her distant relationship (and rather strange one at that) with her own mother and the relationship with Jay Cee which is built on Jay Cee's own ambition, Esther never truly has a solid mother figure in her life. Think back to Esther's visit to the hospital when the baby is born. This does not paint a nice picture of motherhood--instead, Esther is completely repulsed. ULtimately, Esther rejects the typical path for a woman. She does not marry and become a mother, but instead she simply finds herself by rejecting that path. Plath is leaving a heavy commentary on the idea that traditional expectations are not always beneficial for the individual. Just because individuals A, B, C, D, etc, through Y all succeeded when they followed a specific plan does not mean that Z will succeed as well.