Sema7A and plexinC1 expression in the developing hypothalamus and pituitary. In situ hybridization for Sema7A and plexinC1 on consecutive coronal (A-C, H-K) and sagittal (D-G) sections of the hypothalamus and pituitary. Dorsal is to the top. (A, B) Sema7A and plexinC1 are expressed in highly overlapping patterns during hypothalamic development including in the anterior hypothalamus (AHA) and medial preoptic area (MPO). (C) Sema7A is strongly expressed in several adult hypothalamic nuclei including the suprachiasmatic nucleus (SCN), paraventricular nucleus (PVN) and supraoptic nucleus (SON). In contrast, plexinC1 expression in the adult hypothalamus is largely restricted to the PVN (insert in panel C). (D, E) In the E14 pituitary, Sema7A expression is strongest in Rathke's pouch (RP), whereas plexinC1 labels the neural part of the pituitary (IN). (F, G) At E19, Sema7A is strongly expressed in the anterior (AL) and intermediate (IL) lobes of the pituitary and plexinC1 is largely confined to the neural lobe (NL). The weak plexinC1 signals observed in the intermediate lobe at E19 are not detected at later developmental stages (H). (H, I) In situ hybridization for plexinC1 and immunohistochemistry for α-melanophore-stimulating hormone (α-MSH), a marker of the intermediate and anterior pituitary, on consecutive sections. Note that plexinC1 is confined to the neural, i.e α-MSH-negative, part of the pituitary at P0. (J, K) At P0, Sema7A and plexinC1 are expressed in the projection area of LHRH axons, the median eminence (ME). Sema7A and plexinC1 expression can also be detected in the arcuate nucleus (ARC). 3 V, third ventricle; 7A, Sema7A; C1, plexinC1; HY, hypothalamus; IN, infundibulum; nLOT, nucleus of the lateral olfactory tract; opt, optic nerve. Scale bar 390 μm (A, B), 425 μm (C), 750 μm (insert C), 211 μm (D, E), 360 μm (F, G), 425 μm (H, I), and 40 μm (J, K).