Immunoreactive luteinizing hormone (ir-LH) cells in the lung and stomach of chick embryos

Abstract

Luteinizing hormone (LH) immunoreactivity was detected in the lung and stomach of chick embryos by the immunoperoxidase staining technique using specific antiserum to chicken LH. Immunoreactive LH (ir-LH) cells first appeared in the primordial cells of the epithelial layer of lung bud and foregut as well as of Rathke s pouch in the 3-day-old embryo, Hamburger and Hamilton stage 21. Ir-LH cells increased in number with advancing age of embryos in the lung, stomach, and pituitary gland. In the lung of 7-day-old embryos, stage 31, the ir-LH cells were distributed in the epithelium of primary, secondary, and tertiary bronchi, and their shapes were pseudostratified columnar, simple columnar, and simple cuboidal, depending on their sites in the intrapulmonary airway. Ir-LH cells were more numerous in the median part than in the lateral part of the lung, and the population in the epithelial layer of entobronchi of the secondary bronchi was 4 times higher than that in ectobronchi and laterobronchi of the secondary bronchi and in the primary bronchi. The immunoreactive products were found, either in the entire cell or in the apical part, facing the lumina of bronchi. In the stomach, ir-LH cells were found in the epithelial layer of gastric glands. No ir-LH cells were observed in interstitial regions, which consisted of mesenchymal cells and blood vessels, in the lung and stomach tissues. With advancing age, ir-LH cells changed their shapes to flat or squamous, coincident with the formation of parabronchi. Other pituitary hormones were not observed immunohistochemically in either the lung or stomach before hatching. Preabsorption of the antiserum against avian LH with the purified chicken LH or the extract of pituitaries from 10-day-old embryos completely destroyed the immunoreactivity to the cells in the lung and the pituitary. A single band of the immunoreaction products, whose molecular weight was around 25 K daltons, was shown by the immunostaining of nitrocellulose membrane transblotted after sodium dodecylsulphate-polyacrylamide gel electrophoresis of the purified pituitary LH, extracts of pituitaries from 10-day-old embryos, and the extracts of lungs from 7-, 10-, and 14-day-old chick embryos. These results demonstrated that ir-LH cells are present in extrapituitary tissues, and may play an important role during the development of chick embryonic lung and stomach.

Extra-pituitary growth hormone in peripheral tissues of early chick embryos

“…The expression of GH in pituitary tissue is also a phylogenetic development, since GH-like proteins are present in primitive vertebrates and in invertebrates lacking pituitary glands (Wright 1986, Inestrosa et al 1990, Swinnen et al 1990. Moreover, as luteinizing hormone immunoreactivity also occurs in the stomach and lungs of early chick embryos (Shirasawa et al 1996), the extra-pituitary production of pituitary hormones prior to pituitary differentiation may be a general phenomenon.…”

Parotid gland tissue is able partially to assume pituitary functions under the influence of hypothalamic factors: in vivo and in vitro studies

“…Pituitary hormones have been found to be produced during ontogeny (Shirasawa et al 1996) in lung and stomach cells of chick embryos, thus confirming that at least over a certain period, pituitary hormones can be produced in normal extra-pituitary tissues. GH has also been demonstrated in human thymomas by immunohistochemistry and in situ hybridization (Lauriola et al 1997).…”

Extrapituitary production of anterior pituitary hormones: an overview

“…In the chick embryo, luteinizing hormone (LH) is found in the epithelial cells of the developing lung and stomach as early as ED3 of the 21-day incubation period, indicating a potential paracrine role for LH in early embryogenesis [131]. There are also indications that LH and LH receptors [132] are present in the developing retina [69], suggesting possible roles in early retinal development or maintenance.…”