Immunohistochemistry of the hypothalamic neuropeptides and anterior pituitary cells in the Japanese quail

Abstract

The pars distalis of the avian adenohypophysis consists of well-defined cephalic and caudal lobes which are distinct in their cellular constituents. Immunocytochemical investigations on the pituitary hormones of the pars distalis of the Japanese quail reveal five types of secretory cells, adenocorticotropin (ACTH) cells, prolactin (PRL) cells, thyroid-stimulating hormone (TSH) cells, growth hormone GH (STH) cells, and FSH/LH (gonadotropic) cells. The ACTH cells, TSH cells, and PRL cells are restricted to the cephalic lobe, and GH (STH) cells are confined to the caudal lobe, while FSH/LH cells are distributed throughout the cephalic and caudal lobes. The median eminence of birds has distinct anterior and posterior divisions, each with different neuronal components. The avian hypophysial portal vessels also consists of two groups, anterior and posterior. The peculiar arrangement and distribution of the avian hypophysial portal vessels are possibly related to the distribution of neuropeptides in the two divisions of the median eminence and to the cytological and functional differentiation of two lobes of the pars distalis. The localization of perikarya and fibers containing luteinizing hormone releasing hormone (LHRH), somatostatin, vasotocin, mesotocin, corticotropin-releasing factor (CRF), vasoactive intestinal polypeptide (VIP), glucagon, metenkephalin, and substance P in the hypothalamus and median eminence of the Japanese quail has been investigated by means of immunohistochemistry using antisera against the respective neuropeptides. LHRH-, somatostatin-, VIP-, met-enkephalin-, and substance P-immunoreactive fibers are localized in the external layer of the anterior and posterior divisions of the median eminence, while CRF- and vasotocin-reactive fibers are demonstrated only in the external layer of the anterior division of the median eminence. The metenkephalin fibers are thicker in the anterior median eminence but the substance P fibers are more abundant in the posterior division. Mesotocin fibers occur only in the internal layer of the median eminence and neural lobe.

Development of Gonadotropes in the Chicken Embryonic Pituitary Gland

“…The anterior lobe of the avian pituitary gland consists of well-defined cephalic and caudal lobes, and the hormoneproducing cells in these lobes show unique distribution patterns; i.e., corticotropes, lactotropes and thyrotropes are mainly distributed in the cephalic lobe (Hansen et al ., 1977;Iturriza et al ., 1980;Mikami et al ., 1984;Thommes et al ., 1983), and somatotropes are found in the caudal lobe (Hansen et al, 1977;Mikami et al, 1984). On the other hand, gonadotropes are localized in both lobes (Ravona et al, 1973;Mikami et al, 1984).…”

“…On the other hand, gonadotropes are localized in both lobes (Ravona et al, 1973;Mikami et al, 1984).…”

Regulation of Prolactin Secretion by Dopamine at the Level of the Hypothalamus in the Turkey

“…VIP is secreted by neurons which are concentrated within the mediobasal hypothalamus, in a comprehensive area referred to as the infundibular nuclear complex (INF). These neurons project to the external layer of the median eminence (ME) [7, 8, 9, 10, 11]. From the ME, VIP is transported via the hypothalamic-pituitary portal blood vessels to the anterior pituitary, where it acts on VIP receptors probably located on lactotrope cells [1, 12].…”

Development of Thyroid-Stimulating Hormone Beta Subunit-Producing Cells in the Chicken Embryonic Pituitary Gland

“…Although the pars distalis of the pituitary gland of hagfish is simply a cell mass, that of vertebrates of an order higher than the lamprey can be divided into some regions that contain the same cell populations. The avian pituitary gland consists of well-defined cephalic and caudal lobes, and it has been shown that hormone-producing cells in these lobes have unique distribution patterns; i.e., gonadotropes are localized in both lobes [Ravona et al, 1973;Mikami and Yamada, 1984;Sasaki et al, 2003], whereas cortico-Nakamura/Iwasawa/Kidokoro/Komoda/ Zheng/Maseki/Inoue/Sakai tropes, lactotropes and thyrotropes are mainly distributed in the cephalic lobe [McKeown, 1973;Ferrand et al, 1974;Hansen and Hansen, 1977;Jozsa et al, 1979;Sharp et al, 1979;Iturriza et al, 1980;Thommes et al, 1983;Mikami and Yamada, 1984;Berghman et al, 1993;Reichardt, 1993;Sasaki et al, 2003]. On the other hand, somatotropes are found only in the caudal lobe [Hansen and Hansen, 1977;Mikami and Yamada, 1984;Sasaki et al, 2003].…”