What reproductive organs are present in monotremes?

Monotremes, such as the platypus and echidna, possess unique reproductive organs that include cloaca, which serves as a common opening for excretion and reproduction. Female monotremes have specialized mammary glands that produce milk, though they lack nipples; milk is secreted through openings in the skin and pools in grooves for the young to lap up. Males have testes that remain internal and do not descend into a scrotum, which is unlike most other mammals. Additionally, male monotremes have spurs on their hind limbs that can deliver venom.