Question

For each aspect A–E of the male and female reproductive systems, select the most appropriate option from the following list of hormones. 

1. Follicle-stimulating hormone. 

2. Gonadotrophin-releasing hormone. 

3. Inhibin. 

4. Luteinizing hormone. 

5. Oestradiol. 

6. Progesterone. 

7. Testosterone. 

A. A peptide hormone formed in testes and ovaries which acts as a local growth factor and also gives negative feedback to the hypothalamic–pituitary axis. 

B. A steroid hormone formed in the testes which is necessary for normal spermatogenesis. 

C. A peptide hormone formed in the hypothalamus which is necessary for normal spermatogenesis. 

D. A steroid hormone which accounts for the rise in metabolic rate in the second half of the menstrual cycle. 

E. A peptide hormone which plays a major role in both ovulation and the activity of the interstitial (Leydig) cells in the testis.

Answer 1

A. Option 3 Inhibin. This hormone (like many others) exists in several forms sometimes referred to as the inhibins; in the testis it is formed by Sertoli cells which nurture spermatozoa, so are a marker for spermatogenesis, completing the feedback loop. 

B. Option 7 Testosterone. Among its widespread effects, testosterone, which is formed by interstitial cells of the testis, is responsible for spermatogenesis in the seminiferous tubules. 

C. Option 2 Gonadotrophin-releasing hormone. This key hormone is required for the release of follicle-stimulating and luteinizing hormones in both sexes, so is responsible for all sexual activity; control by the hypothalamus allows the complicated control which is different in the two sexes, so that, while male sexual activity shows no regular fluctuation, female sexual activity follows the monthly cycle, which can be modified by nutritional and psychological factors. 

D. Option 6 Progesterone. As implied by its name, this hormone is particularly associated with gestation; in the second half of the cycle it stimulates development in the endometrium which favours implantation of a fertilized ovum. 

E. Option 4 Luteinizing hormone. A surge of this hormone is the precursor of ovulation and it also acts in the testis, giving it the secondary name of interstitial cell-stimulating hormone; note that, as in the body generally, hormones are either peptide or steroid based; in the reproductive system the peptides tend to be common to male and female, whereas the steroids make the difference.