title: Development of projections of primary afferent fibers from the hindlimb to the gracile nucleus: a WGA-HRP study in the rat.
abstract: The projection of primary afferent fibers to the gracile nucleus was studied during development. Injections of wheat germ agglutinin-horseradish peroxidase were made into the hindlimb of fetal, postnatal and adult rats. In most cases the sections were alternately stained for wheat germ agglutinin-horseradish peroxidase including counter stain with Neutral red and for acetylcholinesterase. At embryonic day 17 labelled fibers could be traced to the mid-cervical spinal cord but not further rostrally. At embryonic days E18 and E19 labelled fibers penetrate the rostral pole of the nucleus, which does not happen more caudally. At embryonic day E21 the caudal-most pole of the gracile nucleus still is not penetrated by labelled fibers. From postnatal day 1 onwards labelled fibers are found throughout the entire rostrocaudal extent of the gracile nucleus. These results suggest that primary afferent fibers from the hindlimb first grow to the rostral pole of the gracile nucleus and penetrate the rostral pole immediately upon their arrival. During further development more caudal parts of the gracile nucleus are gradually penetrated in a rostrocaudal fashion by primary afferent fibers of the hindlimb.
authors.affiliation: Department of Physiology, University of Leiden, The Netherlands.
authors.forename: W J
authors.initials: WJ
authors.lastname: Wessels
authors.forename: H K
authors.initials: HK
authors.lastname: Feirabend
authors.forename: E
authors.initials: E
authors.lastname: Marani
mesh_terms: D000344:Afferent Pathways / Q000502:physiology; D000818:Animals; D006614:Hindlimb / Q000196:embryology / Q000254:growth & development / Q000294:innervation*; D006735:Horseradish Peroxidase; D008526:Medulla Oblongata / Q000196:embryology / Q000254:growth & development / Q000502:physiology*; D009412:Nerve Fibers / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D012584:Sciatic Nerve / Q000502:physiology; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate; D014909:Wheat Germ Agglutinins
chemical_list: D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate; D014909:Wheat Germ Agglutinins; D006735:Horseradish Peroxidase