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At least 19 recordsLinked to original sources

PubMed1997

Characteristics of GnRH binding in the gonads and effects of lamprey GnRH-I and -III on reproduction in the adult sea lamprey.

In the present study, both lamprey GnRH-I and -III stimulated steroidogenesis and induced ovulation in adult female sea lampreys during their final reproductive stage. One injection of lamprey GnRH-III at 0.1 or 0.2 microg/g lamprey stimulated plasma estradiol levels in lampreys held at each of three water temperatures, 13 degrees , 17 degrees , and 19 degrees , corresponding to increasing stages of maturation. Four successive injections, 3 to 4 days apart, of lamprey GnRH-III at 0.1 or 0.2 microg/g body weight induced ovulation in 100 or 88% of lampreys, respectively, compared to 21% in controls by Day 31. Lamprey GnRH-III also had a direct stimulatory effect on estradiol production in the sea lamprey gonads in vitro. Lamprey GnRH-III at 100 or 1000 ng/ml stimulated estradiol levels in media incubated with either lamprey ovaries or testes. In contrast to a previous finding in which lamprey GnRH-III was more potent than lamprey GnRH-I in inducing spermiation in adult male sea lampreys (Deragon and Sower, 1994), the results from the present study indicate that lamprey GnRH-I and -III are equally potent in inducing ovulation and stimulating steroidogenesis in female sea lampreys. In addition, GnRH binding sites have been demonstrated for the first time in both the testis and the ovary of the adult sea lamprey using an analog of mammalian GnRH ([D-Lys6] mammalian GnRH) as a labeled ligand. Scatchard analysis suggested the presence of a high affinity binding site in both the testis and the ovary. In summary, lamprey GnRH-III is biologically active in stimulating the pituitary-gonadal axis in adult female sea lampreys. This is the first report demonstrating the presence of a GnRH binding site in the gonads of an Agnathan. The evidence for a direct stimulatory effect of lamprey GnRH in the gonads, the presence of GnRH binding site, and the absence of GnRH in the plasma suggest that, like other vertebrates including rat, rabbit, teleost fish, and human, there may be a GnRH-like factor produced in the gonads of the lamprey and it may act as a paracrine/autocrine modulator of gonadal function. This study further strengthens the paracrine regulatory role of GnRH peptides in the gonads of vertebrates, which appear to be evolutionarily conserved.

Animals↗

PubMed2006

Functional characterization and kinetic studies of an ancestral lamprey GnRH-III selective type II GnRH receptor from the sea lamprey, Petromyzon marinus.

The recently cloned lamprey GnRH receptor was shown to have several unique features, including the longest intracellular C-terminal tail (120 amino acids (aa)) of any previously described GnRH receptor. In the current study, a series of experiments were performed examining cAMP responses, binding kinetics, whole cell competitive binding assays and internalization studies of the lamprey GnRH receptor using a series of three C-terminal tail truncations (80 aa, 40 aa and 0 aa) to better describe the functional significance of this unique vertebrate GnRH receptor. Activation of the lamprey GnRH receptor was shown to stimulate cAMP production in a dose-dependent manner when treated with either lamprey GnRH-I (LogEC50 -6.57+/-0.15) or lamprey GnRH-III (LogEC(50) -8.29+/-0.09). Truncation analysis indicated that the membrane proximal 40 aa of the lamprey GnRH receptor C-terminal tail contain a motif required for cAMP accumulation. Saturation binding assays using the wild type and truncated lamprey GnRH receptors revealed that all of three truncated lamprey GnRH receptors were capable of binding lamprey GnRH-I. Competitive, intact cell-binding assays suggested that the lamprey GnRH receptor is lamprey GnRH-III selective, based on the observed pharmacological profile: lamprey GnRH-III (Inhibitory constant (Ki) 0.708+/-0.245 nM)=chicken GnRH-II (Ki 0.765+/-0.160 nM) > mammalian GnRH (Ki 12.9+/-1.96 nM) > dAla(6)Pro(9)NEt mammalian GnRH (Ki 21.6+/-9.68 nM) > lamprey GnRH-I (Ki 118.0+/-23.6). Finally, the lamprey GnRH receptor was shown to undergo rapid ligand-dependent internalization, which was significantly diminished in the tail-less truncated form. We have shown from our current and our previous structural studies that this unique lamprey GnRH receptor shares several characteristics of both type I and type II GnRH receptors which suggests that this receptor has retained ancestral characteristics that can provide insight into the function and evolution of the vertebrate GnRH receptor family.

Amino Acid Sequence↗

PubMed1997

Lamprey but not porcine insulin binds with different affinity to lamprey and rat hepatocytes.

The displacement of porcine [125I] insulin bound to rat and lamprey isolated hepatocytes with unlabeled lamprey and porcine insulins was investigated. Binding affinity of lamprey insulin for insulin receptor of rat was similar to that of porcine insulin. In contrast, the binding affinity of lamprey insulin for its own insulin receptor was higher than for a rat receptor. To determine the binding affinity constants of lamprey insulin receptor, the competition binding experiments were carried out on isolated lamprey hepatocytes using lamprey insulin as unlabeled ligand and tracer. The affinity of the same binding sites on lamprey hepatocytes was assessed in similar experiments but employing porcine insulin as unlabeled ligand and tracer. It was found that while Kd of low affinity binding sites on lamprey hepatocytes were similar for lamprey and porcine insulins, the Kd of high affinity binding sites was different: the displacement curve for lamprey insulin being shifted to the left as compared to the curve for porcine insulin. The number of high and low affinity binding sites, calculated independently in Scatchard plots, was equal. We conclude that the high affinity insulin binding sites of lamprey but not of rat hepatocytes reveal some species specificity in ligand-receptor interaction.

Animals↗

PubMed2000

Evidence for lamprey GnRH-I and -III-like molecules in the brains of the southern hemisphere lampreys Geotria australis and Mordacia mordax.

The present study has characterized gonadotropic releasing hormone (GnRH)-like molecules in the brains of representatives of the two southern hemisphere families of lampreys, Geotriidae and Mordaciidae. Chromatographic and immunocytochemical evidence showed that the brains of Geotria australis and Mordacia mordax contain two forms of GnRH-like molecules. These two forms correspond to lamprey GnRH-I and -III, which were first sequenced from the brain of the anadromous sea lamprey Petromyzon marinus, a representative of the family Petromyzontidae that is found only in the northern hemisphere. In chromatographic studies (HPLC) using lamprey GnRH-I and -III antiserum, two early eluting GnRH forms coeluted with synthetic lamprey GnRH-I and -III standards. Our studies thus indicate that, despite their apparently long period of separation, the three families of extant lampreys have each retained both of the lamprey GnRH (-I and -III forms) molecules. Moreover, immunocytochemical localization of lamprey GnRH indicated that the pattern of its distribution in the adult brain of at least one of these southern hemisphere lampreys (G. australis) is similar to that previously described for P. marinus. Distribution of GnRH in the brain of larval G. australis was not as extensive as that in larval P. marinus, which may account for the later gonadal development in the former species. The fact that lamprey GnRH-I and -III are the dominant GnRH forms in all three families of lampreys implies that these neurohormones have an ancient origin.

Animals↗

PubMed2004

Cloning and analysis of the lamprey GnRH-III cDNA from eight species of lamprey representing the three families of Petromyzoniformes.

The lamprey, which are divided into three families, including the Petromyzonidae, Geotriidae, and Mordaciidae, have been shown to regulate the reproductive axis through a functional hypothalamic-pituitary-gonadal axis. To date, two forms of gonadotropin-releasing hormone (GnRH) have been identified in the sea lamprey (Petromyzon marinus), lamprey GnRH-I (decapeptide and cDNA) and lamprey GnRH-III (decapeptide), both of which have been shown to be expressed in the preoptic-anterior hypothalamic region and both forms have been demonstrated to regulate reproductive function (i.e. steroidogenesis and gametogenesis). The objective of this study was to isolate the cDNA encoding the prepro-lamprey GnRH-III from eight species of lamprey using a PCR based subcloning procedure. A degenerate primer designed to the lamprey GnRH-III decapeptide was used to amplify the 3' end of each transcript, while gene specific primers were used to amplify the 5' ends. Phylogenetic analysis using the prepro-lamprey GnRH-III amino acid sequences was performed, in which the lamprey GnRH-III sequences divided into three groups, supporting the current view of the lamprey lineage at the family level. Finally, a phylogenetic analysis of these newly identified deduced amino acid sequences together with 64 previously described GnRH sequences suggests that the lamprey GnRHs are unique, as they group together separately from the three previously described paralogous lineages of the GnRH family.

Amino Acid Sequence↗

PubMed1976

Amino acid sequences of lamprey fibrinopeptides A and B and characterizations of the junctions split by lamprey and mammalian thrombins.

The amino acid sequences of the fibrinopeptides A and B from lamprey fibrinogen have been determined. The fibrinopeptide A is the shortest fibrinopeptide ever isolated, being comprised of only six amino acids. The fibrinopeptide B, on the other hand, is the largest fibrinopeptide characterized to date, having 36 amino acid residues and a cluster of covalently bound carbohydrate. As reported previously, lamprey fibrinogen is readily clotted by mammalian thrombins, but only the fibrinopeptide B is released during the process. Lamprey fibrinopeptide A is not released by mammalian thrombins and could only be removed with the use of lamprey thrombin. Firm proof that the lamprey fibrinopeptides A and B are the amino segments of the alpha and beta-chains respectively was obtained by a series of stepwise degradations on lamprey fibrinogen and lamprey fibrins produced in turn by the action of mammalian thrombin (fibrin B) and lamprey thrombin (fibrin A). These studies were supplemented by stepwise degradations on the individual Aalpha and Bbeta-chains. It the case of the lamprey Aalpha-chain it was also possible to release the 6-residue fibrinopeptide A from the isolated chain with lamprey thrombin and demonstrate that the newly exposed amino-terminal sequence begins with the Gly-Pro-Arg sequence characteristic of mammalian fibrin alpha-chains. In fact, the sequences on the fibrin side of both of the junctions split by thrombin(s) are highly conserved and virtually identical with those found in mammalian alpha and beta-chains.

Amino Acid Sequence↗

PubMed1987

Development of the spinal nerves of the larval lamprey: IV. Spinal nerve roots of 21-mm larval and adult lampreys, with special reference to the relation of meninges with the root sheath and the perineurium.

Spinal nerve roots of 21-mm larval and adult lampreys were electron microscopically studied. In 21-mm larval lampreys, each ventral and dorsal rootlet contains axons of various diameters enclosed together as groups in individual troughs of a Schwann cell cytoplasm, lying in direct contact with one another, and is further ensheathed entirely by a basal lamina. Dorsal roots possess visceral axons, while ventral roots lack them. In adult lampreys the ventral and dorsal roots possess individual sheaths for larger somatic axons, each being surrounded by a single Schwann cell and the basal lamina and separated from one another by a considerable amount of connective tissue. Visceral fibers are present in both the dorsal and ventral roots of adult lampreys. They aggregate to form fascicles that lie among somatic axons, being separated from them. Two layers of the meningeal tissue invaginate to form a root sheath around the distal portion of individual dorsal and ventral roots of 21-mm larval lampreys. In adult lampreys the sheath is similarly formed but extends over most of the dorsal and ventral roots. The perineurium is not developed in 21-mm larval lampreys, but is present and ensheaths only the proximal portion of spinal nerve trunks outside the meninges in adult lampreys: it is completely absent along most of the length of peripheral nerves. In both larval and adult lampreys, the outer cell layer of the root sheath is open-ended near the middle of nerve roots with respect to the extramedullary connective tissue space. Similar loosening of the cellular barrier is seen along blood vessels. Thus, the outer meningeal fibrous layer is directly continuous with the extra medullary connective tissue space by way of the inner fibrous layer of the root sheath.

Animals↗

PubMed1994

Effects of lamprey gonadotropin-releasing hormone-III on steroidogenesis and spermiation in male sea lampreys.

The biological activities of lamprey gonadotropin-releasing hormone-III (GnRH-III) were determined in the adult male sea lamprey, Petromyzon marinus. One injection of lamprey GnRH-III at 0.1 or 0.2 microgram/g body wt stimulated plasma estradiol and progesterone levels in adult male sea lampreys undergoing final maturation. Four successive injections of lamprey GnRH-III at 0.1 microgram/g of lamprey GnRH-1 at 0.2 microgram/g induced spermiation in 78 or 30% of the lampreys, respectively, compared to 0% in controls by Day 16. In summary, lamprey GnRH-III is biologically active in stimulating the pituitary-gonadal axis in adult male lampreys.

Animals↗

PubMed2004

A short consensus repeat-containing complement regulatory protein of lamprey that participates in cleavage of lamprey complement 3.

The prototype of the short consensus repeat (SCR)-containing C regulatory protein is of interest in view of its evolutionary significance with regard to the origin of the C regulatory system. Lamprey is an agnathan fish that belongs to the lowest class of vertebrates. Because it does not possess lymphocytes, it lacks Ig and consequently the classical C pathway. We identified an SCR-containing C regulatory protein from the lamprey. The primary structure predicted from the cDNA sequence showed that this is a secretary protein consisting of eight SCRs. This framework is similar to the alpha-chain of C4b-binding protein (C4bp). SCR2 and -3 of human C4bp are essential for C4b inactivation, and this region is fairly well conserved in the lamprey protein. However, the other SCRs of this protein are similar to those of other human C regulatory proteins. The lamprey protein binds to the previously reported lamprey C3b/C3bi deposited on yeast and cleaves lamprey C3b-like C3 together with a putative serum protease. The scheme resembles the C regulatory system of mammals, where factor I and its cofactor inactivate C3b. Unlike human cofactors, the lamprey protein requires divalent cations for C3b-like C3 cleavage. Its artificial membrane-anchored form protects host cells from lamprey C attack via the lectin pathway. Thus, the target of this protein appears to be C3b and/or its family. We named this protein Lacrep, the lamprey C regulatory protein. Lacrep is a member of SCR-containing C regulators, the first of its kind identified in the lowest vertebrates.

Amino Acid Sequence↗

PubMed2000

The distribution of lamprey GnRH-III in brains of adult sea lampreys (Petromyzon marinus).

In the sea lamprey, Petromyzon marinus, two forms of GnRH, lamprey GnRH-I and -III, have been demonstrated to be neurohormones regulating the pituitary-gonadal axis. The objective of the present study was to determine the distribution of lamprey GnRH-III in the brains of adult sea lampreys and to compare it to the distribution of lamprey GnRH-I. For this purpose, two kinds of immunostaining were employed: one was a single immunostaining by one of two GnRH antibodies using two successive sections; the other was double immunostaining of a single section. A dense accumulation of neuronal cells immunoreactive (ir) to antisera against either lamprey GnRH-I or -III was found in the arc-shaped preoptico-anterior hypothalamic area. Additional smaller numbers of irGnRH cells were found in the periventricular zone of the posterior hypothalamus. In the above-mentioned locations, the distribution of both irGnRH-I and -III cells was intermixed and very similar, but the cells exhibiting GnRH-III immunoreactivity were distinctly different from those exhibiting GnRH-I immunoreactivity. The relative numbers of irGnRH-III cells were larger than those of irGnRH-I cells in the preoptico-anterior hypothalamic area, and more than 90% of GnRH cells in the posterior hypothalamus were irGnRH-III cells. Both irGnRH-I and -III cells projected their fibers primarily into the neurohypophysis. The relative densities of the accumulated irGnRH-III fibers were similar to those of irGnRH-I fibers in the anterior neurohypophysis but higher than those of irGnRH-I fibers in the posterior neurohypophysis. The present study provides further immunocytochemical data to the already compelling physiological evidence that indicates that both lamprey GnRH-I and -III act through the hypothalamic-pituitary-gonadal axis to modulate reproductive processes in the sea lamprey.

Animals↗

PubMed2004

In vitro and in vivo effects of GABA, muscimol, and bicuculline on lamprey GnRH concentration in the brain of the sea lamprey (Petromyzon marinus).

gamma-Aminobutyric acid (GABA) is a neurotransmitter with a demonstrated neuroregulatory role in reproduction in most representative species of vertebrate classes via the hypothalamus. The role of GABA on the hypothalamus-pituitary axis in lampreys has not been fully elucidated. Recent immunocytochemical and in situ hybridization studies suggest that there may be a neuroregulatory role of GABA on the gonadotropin-releasing hormone (GnRH) system in lampreys. To assess possible GABA-GnRH interactions, the effects of GABA and its analogs on lamprey GnRH in vitro and in vivo were studied in adult female sea lampreys (Petromyzon marinus). In vitro perfusion of GABA and its analogs at increasing concentrations (0.1-100 microM) was performed over a 3-h time course. There was a substantial increase of GnRH-I and GnRH-III following treatment of muscimol at 100 microM. In in vivo studies, GABA or muscimol injected at 200 microg/kg significantly increased lamprey GnRH concentration in the brain 0.5 h after treatment compared to controls in female sea lampreys. No significant change in lamprey GnRH-I or GnRH-III was observed following treatment with bicuculline. These data provide novel physiological data supporting the hypothesis that GABA may influence GnRH in the brain of sea lamprey.

Animals↗

PubMed1997

Characterization of lamprey rhodopsin by isolation from lamprey retina and expression in mammalian cells.

A visual pigment was extracted from lamprey retina and was expressed in cultured mammalian cells (293S) using a cDNA fragment isolated from lamprey retina. The extracted pigment, a putative lamprey rhodopsin, had an absorption maximum at 503 nm. The recombinant lamprey rhodopsin, reconstituted with 11-cis-retinal, showed an absorption maximum at about 500 nm. Both pigments reacted with an anti-bovine rhodopsin antibody (Rh29), which recognizes the short photoreceptor cells in lamprey retina. Unlike rhodopsins of higher vertebrates, the lamprey rhodopsin bleached gradually in the presence of 100 mM hydroxylamine even in the dark. Our results suggest that, despite its high similarities with other vertebrate rhodopsins, lamprey rhodopsin has a character different from those of higher vertebrates.

Animals↗

PubMed1977

Comparison of the cross-linking patterns of lamprey fibrinogen and fibrin by the action of the intrinsic lamprey factor XIII and human factor XIII during the process of blood coagulation.

Intrinsic lamprey factor XIII cross-links the gamma chain of lamprey fibrin (50,000 daltons) to the gamma-dimer (100,000 daltons). The alpha-chain (110,000 daltons) is cross-linked very slowly to alpha-dimer (210,000 daltons) and alpha-trimer (330,000 daltons). In contrast, human factor XIII, when added in combination with intrinsic lamprey factor XIII, cross-links the alpha-chain of lamprey fibrin to a high molecular weight polymer, and any remaining gamma-chain is also cross-linked to a polymer. However, the gamma-chain that has previously cross-linked to the gamma-dimer by the intrinsic lamprey factor XIII remains as a gamma-dimer. Factor XIII-free lamprey fibrin cross-links all its subunits (alpha, beta, gamma) to high molecular weight polymers when human factor XIII is added. In contrast to human and bovine fibrin where alpha-chain cross-linking in the process of blood coagulation commences when all of the gamma-chain has cross-linked, the lamprey alpha-chain will begin to cross-link when approximately half of the gamma-chain has cross-linked to the gamma-dimer.

Animals↗

PubMed1999

Possible gonadotropin cells in the lamprey pituitary: colocalization of mammalian LH-like immunoreactivity and glycoconjugate in adult sea lampreys (Petromyzon marinus).

In lampreys, although gonadotropin (GTH) has not yet been isolated from the pituitary gland, the presence of GTH has been strongly suggested. To detect possible GTH in the sea lamprey (Petromyzon marinus) pituitary, two different cytochemical probes were tested: One was the use of antibodies to GTHs, and the other was the use of lectin-screening kits for demonstration of glycoconjugate in hormonal molecules. GTH-like immunoreactivity was found in cells distributed in the ventral half of the proximal pars distalis. These cells were stained intensely by all four lots of anti-ovine LH including LHbeta, and were stained moderately or weakly by several other antibodies to LH-related GTHs, such as human LHbeta, hCGbeta, amphibian LH, and sturgeon GTH IIbeta. On the other hand, there were no positive reactions in the sea lamprey pituitary using the antibodies to FSH-related GTHs, thyrotropin (TSH), or pituitary glycoprotein hormones of teleost origin. Thus, GTH-like material in the sea lamprey pituitary seems to be more closely related to mammalian-like LH, rather than to FSH or TSH, as far as immunocytochemical determinants. A total of 21 kinds of lectins was tested. Among those, GTH-positive cells were also stained positively by concanavalin A and Vicia villosa agglutinin. Thus, the present study demonstrates colocalization of LH-like immunoreactivity and glycoconjugate in cells in the ventral half of the proximal pars distalis of the sea lamprey pituitary. It is suggested that those cells are most likely to be GTH cells in the sea lamprey pituitary.

Animals↗

PubMed1986

Profiles of the female-specific serum protein in the Japanese river lamprey, Lampetra japonica (Martens), and the sand lamprey, Lampetra reissneri (Dybowski), in relation to sexual maturation.

The occurrence of female-specific serum protein (FSSP) was examined in the anadromous lamprey, Lampetra japonica, and a freshwater lamprey, Lampetra reissneri, by an immunodiffusion technique using antiserum raised against the serum of sexually mature female lamprey. A considerable amount of FSSP was consistently detected in the blood of vitellogenic, but not in that of nonvitellogenic, females of both species of lampreys. The relative amount of the FSSP tended to become larger in female lampreys at the spawning period. The FSSP may correspond to the yolk precursor protein which is incorporated into ovarian oocytes during the period of exogenous vitellogenesis in the lampreys.

Aging↗

PubMed1965

DIFFERENCES IN THE CLOTTING OF LAMPREY FIBRINOGEN BY LAMPREY AND BOVINE THROMBINS.

1. Improved methods for the purification of lamprey thrombin and fibrinogen are presented. 2. Lamprey thrombin releases two fibrinopeptides from lamprey fibrinogen during the transformation into fibrin. Bovine thrombin releases only one of these, a peptide referred to as fibrinopeptide B. The differences in the by-products of fibrin formation are reflected in the different N-terminal amino acid compositions of the two types of fibrin. 3. The fibrinopeptide that is not removed from the lamprey fibrinogen by bovine thrombin can subsequently be released by treatment of that fibrin with lamprey thrombin. 4. Under the conditions used, lamprey thrombin releases both fibrinopeptides at about the same rate. 5. The differences in interaction among these pairs of related proteins are extreme manifestations of the phenomenon loosely referred to as ;species specificity'.

Amino Acids↗

PubMed2005

Expression of neuropeptide Y family peptides in the brain and gut during stages of the life cycle of a parasitic lamprey (Petromyzon marinus) and a nonparasitic lamprey (Ichthyomyzon gagei).

The long-term objective of our research is to show that internal factors may be key to triggering metamorphosis and directing the life history types in lampreys (parasitism versus nonparasitism). Since neuropeptide Y family peptides are key players in the endocrine-mediated feeding and reproductive events in mammals, a role for these peptides in the control of feeding behavior and development can be predicted for lampreys. We have investigated the expression pattern of these peptides in the brain and in the gut during different stages of the life cycle of the parasitic lamprey, Petromyzon marinus, and the nonparasitic lamprey, Ichthyomyzon gagei. We provide a description of the cloning and sequencing of P. marinus and I. gagei cDNA for neuropeptide Y (NPY), peptide tyrosine-tyrosine (PYY), and peptide methionine-tyrosine (PMY). Using sequence-specific primers, the mRNA expression patterns for these peptides in brain and gut of larval (ammocoete) and adult (juvenile, prespawning) lampreys were examined by semiquantitative RT-PCR. The observations extend a potential role of neuropeptide Y family peptides in the modulation of feeding behavior and reproductive maturity in lampreys.

Amino Acid Sequence↗

PubMed1995

Distribution of lamprey adrenocorticotropin and melanotropins in the pituitary of the adult sea lamprey, Petromyzon marinus.

Three peptides containing the melanotropin (MSH)-core sequence, YXMXHFRWG, have been isolated recently from the pituitary glands of adult sea lampreys (Petromyzon marinus) and were tentatively assigned as lamprey adrenocorticotropin (ACTH), MSH-A, and MSH-B, respectively. Both MSHs differed significantly from gnathostome MSHs and cannot be assigned as alpha-MSH, beta-MSH, or gamma-MSH. The aim of the present study was to localize these peptides in the lamprey pituitary using antisera generated against synthetic lamprey ACTH1-16, MSH-A, and MSH-B. ACTH-like immunoreactivity was found in most cells of the rostal pars distalis (RPD) and in a few scattered cells of the proximal pars distalis (PPD). MSH-A-like immunoreactivity was found in most cells of the RPD, a few scattered cells of the PPD, and almost all cells of the pars intermedia (PI). MSH-B-like immunoreactivity was found only in the PI, where almost all cells were stained. Thus, the topographic distributions of ACTH and MSHs in the lamprey pituitary were similar to those in gnathostome vertebrates.

Adrenocorticotropic Hormone↗