Figure 4
From: Placental expression of pituitary hormones is an ancestral feature of therian mammals
Origin of pituitary hormone expression in the mammalian placenta. Expression of the pituitary hormones GH, GH-R, PRL and LH-β in the yolk-sac placenta of the tammar wallaby suggest that these hormones may have provided a general function in the placenta of the common ancestor of therian mammals (blue dot). From this generalized expression, the placentas of some eutherian mammals including humans have developed specific gene copies including HCG, GH-V (red dots; NV indicates no sequence variants in those species; GH, growth hormone; GH-R, growth hormone receptor; GH-V, growth hormone variant; HCG, human chorionic gonadotrophin; LH-β, luteinizing hormone subunit-β; PRL, prolactin; NV, no variants).