Complex sentence: The cell bodies produce two closely-related peptide hormones, vasopressin and oxytocin, and every supraoptic neuron is thought to make either oxytocin or vasopressin, although a few make both.
Split into simpler sentences: The cell bodies produce two closely-related peptide hormones, vasopressin and oxytocin. Every supraoptic neuron is thought to make either oxytocin or vasopressin, although a few make both.