A 23-year-old female is being evaluated for infertility. Hormone studies reveal a normal rise in the blood estradiol level during the first phase of the menstrual cycle. Androgens synthesized in this patient's ovaries are converted to estradiol in which of the following cell types?

Question

A 23-year-old female is being evaluated for infertility.  Hormone studies reveal a normal rise in the blood estradiol level during the first phase of the menstrual cycle.  Androgens synthesized in this patient's ovaries are converted to estradiol in which of the following cell types?

Quizplus · Accepted Answer

11ec160b_3cbc_0967_9249_27a49403fa97_MD0001_00 Estradiol, the predominant estrogen in the human body, is primarily derived from androgens. Androgens and progesterone are synthesized from cholesterol in the theca interna cells under the influence of luteinizing hormone (LH). Androgens released from the theca interna cells migrate into the nearby granulosa cells, which contain the enzyme aromatase. Aromatase converts the androgens into estradiol. This reaction is stimulated by follicle stimulating hormone (FSH). (Choice B) The theca externa lies outside of the theca interna and does not participate in steroidogenesis. The theca externa is composed of a layer of smooth muscle and fibroblast cells. It serves as a connective tissue support structure for the follicle. (Choice D) Oocytes do not make the aromatase enzyme needed for conversion of androgens to estradiol. All female oocytes are formed during embryogenesis and remain arrested in prophase I until ovulation occurs. At each ovulation, a single oocyte completes meiosis I. Meiosis II occurs after fertilization. (Choice E) Leydig cells are found only in the male testes. They are analogous in location and function to the theca interna cells of the ovarian follicle. Leydig cells are stimulated by LH to secrete testosterone. Educational Objective: LH stimulates the theca interna cells of the ovarian follicle to produce androgens. Aromatase within the follicle's granulosa cells subsequently converts these androgens to estradiol under FSH stimulation. The theca externa cells serve as a connective tissue support structure for the follicle.

A 23-Year-Old Female Is Being Evaluated for Infertility