Development of the ectopically transplanted primordium of epithelial hypophysis (anterior neural ridge) in Bufo japonicus embryos.
It has recently been demonstrated that the epithelial pituitary of the toad is not stomodeal, but placodal, in origin. The placodal cells in the anterior part of the neural ridge (ANR) of the open neurulae are the exclusive source of the epithelial pituitary gland. The present study was undertaken to see the self-differentiating ability of these cells in an ectopic environment. Bufo japonicus embryos at the tailbud stage received implants of either the ANR from open-neurula-stage embryos, or the pituitary primordium from tailbud-stage embryos (the ANR derivative beneath the forebrain floor) into the tail. Development of the pars intermedia and the pars distalis was monitored immunohistochemically using antisera against both synthetic alpha melanophore-stimulating hormone (alpha MSH) and bullfrog prolactin (PRL). Neither the immunoreactive alpha MSH cells nor the immunoreactive PRL cells differentiated from the neural ridge when it was dislocated from the original site at the open neurula stage. On the other hand, in grafts of the pituitary primordium transplanted from the tailbud-stage embryos, immunoreactive PRL cells developed invariably and immunoreactive alpha MSH cells were detected at an incidence of 72%. The significance of the role of brain tissue surrounding the pituitary anlage in differentiation of the pars intermedia and pars distalis is discussed.
Department of Biology, School of Education, Waseda University, Tokyo, Japan.
S
S
Kikuyama
H
H
Inaco
B G
BG
Jenks
K
K
Kawamura
D000818:Animals; D002025:Bufonidae; D004848:Epithelium / Q000196:embryology / Q000637:transplantation; D005260:Female; D007158:Immunologic Techniques; D009074:Melanocyte-Stimulating Hormones / Q000276:immunology; D010902:Pituitary Gland / Q000196:embryology* / Q000637:transplantation; D011388:Prolactin / Q000276:immunology
D011388:Prolactin; D009074:Melanocyte-Stimulating Hormones