Which of the following is not a phase in the menstrual cycle?
a. ovulation
b. luteal
c. gastrulation
d. follicular

I believe the correct answer is gastrulation.

The menstrual cycle is divided into the follicular phase, the menstrual phase, ovulation phase and the luteal phase. The Ovulation phase is a phase between the menstrual cycle just before menstruation starts. Gastrulation on the other hand is a phase in embryogenesis after fertilization has occurred.

This is a phase in between the menstrual cycle and is triggered by a hormone produced by the anterior pituitary gland and is called the Luteinizing hormone. The phase is when the egg has matured from the graafian follicle after it bursts. This egg will travel into the fallopian tube by the help of special structures called fimbriae hoping to be fertilized. If fertilized, the egg will attach to the uterus. If not, it is removed as menstrual blood during menstruation. In this stage, the basal body temperature of the lady increases and she will have more "feelings" for sexual intercourse.

It is triggered by the hormone Luteinizing Hormone (LH) that is released by the anterior pituitary gland. After the graafian follicle releases the ovum, it (graafian follicle) matures into the corpus luteum that produces copious amounts of the hormones progesterone and estrogen to prepare the uterus for implantation by thickening it and making the mucus of the cervix more thinner to allow passage of sperms. If the lady does not become pregnant, the corpus luteum will die and the uterine wall sheds in the menstrual phase.

This is the first phase and it starts on the first day the lady sees her period. It starts due to the anterior pituitary gland secreting the hormone follicle stimulating hormone (FSH) .The hormone will stimulate formation of ovarian follicles in the ovaries and only one matures and produces estrogen to inhibit all the other eggs from maturing and also thickening the uterus. It lasts for 14 days. The ovarian follicle matures into the graafian follicle that enters the ovulatory phase.

This is totally unrelated to the menstrual cycle and it is found in embryology after the egg has been fertilized during the menstrual cycle and matures into an embryo. In this stage of embryogenesis, there is formation of the gut of a developing embryo

Level: High School

Subject: Biology

Topic: Reproduction

b - the respond is innate and varies over time.

good luck!

this is math not biology xd