Search

Gonadotropins GTH I and GTH II from the pituitary of Mediterranean (M.) yellowtail (Seriola dumerilii) were isolated and characterized, and antisera to the whole GTH II molecule (anti-My α,βGTH II) and to its β-subunit (anti-My βGTH II) were obtained. At the light microscopic level, anti-My α,βGTH II reacted with My βGTH II-immunoreactive cells (GTH II cells), thyroid-stimulating hormone (TSH) cells, and a third cell population, which could have been GTH I cells. The aim of this study was the ultrastructural characterization of GTH and TSH cells in M. yellowtail using the immunogold method in order to provide a basis for future research into reproduction of this species. Pituitaries from mature male and female specimens reared in captivity were disected out and processed for electron microscopy. The immunogold method was carried out by using anti-My α,βGTH II, anti-My α,βGTH II preabsorbed with the α subunit of the M. yellowtail GTH (My αGTH-subunit), anti-My βGTH II, anti-human (h) α,βTSH, and anti-h βTSH sera to reveal gonadotropic and thyrotropic cells. M. yellowtail gonadotropic cells were very heterogeneous with regard to their size, shape, and ultrastructural features. Cells were found with numerous, round, variably electron-dense, secretory granules and globules; others were found with their cytoplasm occupied mostly by dilated cisternae of rough endoplasmic reticulum (RER) and scarce secretory granules; and other intermediate cell forms were found that showed varying proportions of secretory granules and dilated RER. The secretory granules and globules were immunogold labeled with anti-My α,βGTH II, and the reaction was weaker in the latter. A similar immunogold-labeling pattern was found with anti-My βGTH II and with anti-My α,βGTH II preabsorbed with the My αGTH-subunit, although some cells that showed the same ultrastructural features described above were not immunogold labeled and could have been GTH I cells. Thyrotropic cells had small, round, secretory granules of medium or high electron density that were immunogold labeled with anti-My α,βGTH II, anti-h α,βTSH, and anti-h βTSH sera, but not with anti-My βGTH II or anti-My α,βGTH II serum preabsorbed with the My αGTH-subunit. All of the cell forms described for gonadotropes and thyrotropes were also found in a state of involution. Gonadotropes that are of a single morphological type but that vary in ultrastructure are present in the pituitary of captive M. yellowtail. GTH II- and putative GTH I-producing cells were distinguishable from one another and from TSH cells by their different reactions to anti-My α,βGTH II, anti-My βGTH II, and anti-My α,βGTH II preabsorbed with the My αGTH-subunit. Anat. Rec. 250:448–458, 1998. © 1998 Wiley-Liss, Inc.

Melanotropin (MSH) and adrenocorticotropin (ACTH) are pituitary hormones derived from a common precursor: the proopiomelanocortin (POMC), which is processed differently in the melanotropic and corticotropic cells of several vertebrates. While ACTH is a major final product in corticotropes, it is further processed into α-MSH and corticotropin-like intermediate lobe peptide (CLIP) in melanotropes. Cells which are immunoreactive to ACTH (ACTH cells) and to both α-MSH and ACTH (MSH cells) have been described in a number of teleosts, including the Mediterranean yellowtail, by light microscopic immunocytochemistry. However, these cells have been ultrastructurally characterized only in a few species. In this paper, we use electron microscopy to identify and characterize the cells producing MSH and ACTH in M. yellowtail (Seriola dumerilii). Pituitaries from adult specimens were dissected and processed for conventional and immunocytochemical electron microscopy. An immunogold technique was performed using anti-synthetic α-MSH and anti-human (h) ACTH (1-24) sera. MSH cells had round secretory granules with a granular content of varying electron density and compactness, which were immunogold-labeled with anti-α-MSH. Homogeneous and electron-dense secretory granules found in the Golgi area of these cells reacted with both anti-α-MSH and anti-hACTH (1-24). ACTH cells had round secretory granules with a homogeneous and medium or high electron-dense core and narrow clear halo, which were grouped in the cell area near the neurohypophysis (NH). Some granules showed an osmiophilic semicore in the medium electron-dense content, which has not been described in other teleost pituitary cells. Immunogold-labeling over the secretory granules only was obtained with all the antisera used. Some ACTH cells showed involutive features. MSH and ACTH are respective final products of the POMC in two ultrastructurally different cells of the pituitary of M. yellowtail, MSH and ACTH cells. The immature granules in the Golgi area of MSH cells seem to be the site of proteolitic cleavage of ACTH into α-MSH and CLIP. Anat. Rec. 249:74–80, 1997. © 1997 Wiley-Liss, Inc.

Prolactin (PRL), growth hormone (GH), and somatolactin (SL) are structurally related pituitary hormones that belong to a peptide family. Whereas growth hormone and prolactin are present in the hypophysis of all vertebrates, somatolactin, a recently discovered hormone, has been found only in fish. It has been demonstrated immunocytochemically in a few teleost species; ultrastructurally, cells producing this hormone have been characterized only in one species of salmon. In this paper, we identify and characterize ultrastructurally the cells producing these three hormones in Mediterranean yellowtail (Seriola dumerilii). Pituitaries from adult specimens were dissected out and processed for electron microscopy. The immunogold technique was performed in some ultrathin sections using fish primary antibodies. PRL cells had round, peripherally distributed, very electrondense, homogeneous secretory granules of variable size. GH cells had dense, round secretory granules with a conspicuous scalloped membrane, which were grouped in the cell area near the neurohypophysis. SL cells had round, polymorphic, or very irregularly shaped secretory granules, the last seeming to arise from the fusion of various secretory granules. The population of secretory granules varied greatly from one cell to another. In all cases, immunogold labeling was seen exclusively in the secretory granules. Exocytosis was observed in all cell types. Some of the PRL, GH, and SL cells showed involutive features. PRL, GH, and SL, although structurally and functionally related, are secreted by ultrastructurally different cells in the pituitary of M. yellowtail. Anat. Rec. 247:395–404, 1997 © 1997 Wiley-Liss, Inc.

During the last 4 years we have come to verify that some patients under treatment with 3% minoxidil and 0.01% tretinoin developed sunburns following sun exposure. We related these to the effects of UV radiation on the scalp previously irritated by tretinoin, so the treatment was stopped for 15 to 20 days. About 3 to 4 months later these patients suffered increased hair loss, which first was interpreted as a consequence of having temporarily stopped the medication. Consequently, in our protocol of treatment for male androgenetic alopecia we usually advise patients to avoid using tretinoin in the morning of sunny days, and especially if they plan to go to the beach. REPORT OF A CASE. Recently, a young woman consulted us because she had begun to notice a great loss of hair 4 months after an episode of quite severe sunburns on the scalp during the summer. At that time