Explain the difference between the following terms:
$(1)$ Prostate gland - Bulbourethral gland
$(2)$ Ovary - Ovarian follicle

(N/A) $(1)$ Prostate gland: It is a single gland located at the base of the urinary bladder in males. Its secretion is alkaline and helps in the activation and nourishment of sperms.
$\Rightarrow$ Bulbourethral gland: These are paired glands located below the prostate gland on the lateral sides of the urethra. Their secretion helps in the lubrication of the penis during coitus.
$(2)$ Ovary: It is the primary female sex organ located on both sides of the uterus. It is responsible for the production of the ovum and the secretion of female sex hormones like estrogen and progesterone.
$\rightarrow$ Ovarian follicle: These are the structural and functional units of the ovary. They represent different stages of development of the tissues surrounding the oocyte (egg cell) within the ovary.