Which hormone is necessary for the growth of endometrial glands which are important for the sustenance of a growing embryo until its implantation?

The correct answer is estrogen.

Endometrial glands are uterine glands located inside the endometrium. Their appearance varies during the menstrual cycle and it is under the influence of hormones. For example, during the proliferative phase, uterine glands appear due to estrogen secretion by the ovaries while during the secretory phase, due to increase in progesterone secretion, the uterine glands become very coiled with wide lumens and produce a secretion.