Developmental changes of Islet-1 and its co-localization with pituitary hormones in the pituitary gland of chick embryo by immunohistochemistry.
Although Islet-1 expression in the pituitary gland of early mouse embryo has been previously described, there are no reports concerning the correlation of Islet-1 expression with lineage restrictions in cell types at the later stages of pituitary development. The role of Islet-1 in chickens is also unknown. The purpose of this study was to follow, by using immunohistochemistry, the ontogeny of pituitary Islet-1 and the various cell types that contain Islet-1 throughout chick embryo development. A few Islet-1-immunopositive (Islet-1(+)) cells were first detected in the pituitary primordium in two out of six embryos at embryonic day 5.5 (E5.5), most of the Islet-1(+) cells being ventrally located. As development progressed, many more Islet-1(+) cells were observed throughout the pars distalis. The relative percentage of Islet-1(+) cells amongst the total Rathke's pouch cells was 4.4% at E6.5. This increased significantly, reaching 11.1% by E10.5, followed by no significant change until hatching. Dual immunohistochemistry showed that adrenocorticotrophs, somatotrophs and lactotrophs did not express Islet-1. The cellular types expressing Islet-1 included luteinizing-hormone-positive (LH(+)) gonadotrophs and thyroid-stimulating-hormone-positive (TSH(+)) thyrotrophs. The cells co-expressing LH and Islet-1 were initially detected at E6.5, the proportion of LH(+) cells possessing Islet-1 being about 4%; this increased to 63% at E14.5, followed by no significant changes until hatching. TSH and Islet-1 co-localized cells were first observed at E10.5, with about 37% TSH(+) cell expressing Islet-1; this increased to about 50% by E16.5, after which there was no evident change until hatching. These results suggest that Islet-1 is involved in determining the cell lineages, proliferation, differentiation and maintenance of hormone-secreting functions of pituitary gonadotrophs and thyrotrophs of chick embryo.
Liu
Jiali
J
College of Biological Sciences, China Agricultural University, Beijing 100094, People's Republic of China.
He
Yuqin
Y
Wang
Xiumei
X
Zheng
Xing
X
Cui
Sheng
S
D000818:Animals; D002642:Chick Embryo; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000378:metabolism*; D007150:Immunohistochemistry; D060850:LIM-Homeodomain Proteins; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D010902:Pituitary Gland / Q000737:chemistry / Q000166:cytology* / Q000196:embryology / Q000378:metabolism*; D010907:Pituitary Hormones / Q000378:metabolism*; D013972:Thyrotropin / Q000378:metabolism; D014157:Transcription Factors
D018398:Homeodomain Proteins; D060850:LIM-Homeodomain Proteins; D009419:Nerve Tissue Proteins; D010907:Pituitary Hormones; D014157:Transcription Factors; C063843:insulin gene enhancer binding protein Isl-1; D013972:Thyrotropin