Differentiate between the following:
$1.$ External reproductive characteristics of male and female.
$2.$ Internal reproductive characteristics of male and female.

(N/A) The differences between male and female reproductive characteristics are as follows:
$1.$ External reproductive characteristics:

Male	Female
$(1)$ Mammary glands are rudimentary.	$(1)$ Mammary glands are well-developed.
$(2)$ Beard and moustache are present.	$(2)$ Beard and moustache are absent.
$(3)$ Muscles are generally stronger.	$(3)$ Muscles are comparatively weaker.
$(4)$ Voice is deep (low pitch).	$(4)$ Voice is sharp (high pitch).

$2.$ Internal reproductive characteristics:

Male	Female
$(1)$ Primary sex organs are testes.	$(1)$ Primary sex organs are ovaries.
$(2)$ Testes are located outside the abdominal cavity in the scrotum.	$(2)$ Ovaries are located inside the abdominal cavity.
$(3)$ Produce sperms.	$(3)$ Produce ova.
$(4)$ Produce male sex hormone,testosterone.	$(4)$ Produce female sex hormones,estrogen and progesterone.