Ontogeny of gamma-melanocyte-stimulating hormone in the brain and hypophysis of the rat: an immunohistochemical analysis.
The ontogeny of gamma-melanocyte stimulating hormone (gamma-MSH)-like immunoreactive (gamma-MSHI) structures in the brain and hypophysis was investigated in the rat by means of indirect immunofluorescence. gamma-MSHI neurons in the arcuate nucleus appeared at Day 13 of gestation, in the anterior hypophysis at Day 16, in the intermediate lobe at Day 18, and in the nucleus commissuralis after birth. gamma-MSHI fibers first appeared at Day 15 of gestation in the hypothalamic area and extended dorsally to reach the surface of the diencephalon. At Day 16 of gestation, another gamma-MSHI fiber bundle was found that ran laterally along the ventral surface of the diencephalon. At Day 19, immunoreactive fibers first appeared in the forebrain, diencephalon, midbrain and upper pons, and thereafter they increased in number, reaching a maximum at postnatal Day 15. gamma-MSHI fibers in the lower pons and medulla oblongata first appeared after birth. They also increased in number with age and reached a maximum at postnatal Day 15. The present ontogenetical study has demonstrated the different times of first appearance of each of the 3 major gamma-MSHI structures-containing cell groups in the brain, i.e., the arcuate nucleus, hypophysis and nucleus commissuralis. These findings may reflect the different functions of 3 groups of cells.
D000818:Animals; D001111:Arcuate Nucleus of Hypothalamus / Q000378:metabolism; D001921:Brain / Q000254:growth & development / Q000502:physiology*; D005455:Fluorescent Antibody Technique; D009074:Melanocyte-Stimulating Hormones / Q000502:physiology*; D009434:Neural Pathways / Q000378:metabolism; D018377:Neurotransmitter Agents / Q000378:metabolism; D010902:Pituitary Gland / Q000254:growth & development / Q000502:physiology*; D051381:Rats
D018377:Neurotransmitter Agents; D009074:Melanocyte-Stimulating Hormones