Ovarian steroidogenesis during follicular maturation in the domestic fowl (Gallus domesticus)

The steroidogenic potential of various physiological compartments within the ovary of the hen were examined using in vitro systems. Three-hour incubations of individual whole small follicles (less than 1 mm-1 cm) or 100,000 collagenase-dispersed theca cells of the five largest ovarian follicles (F1-F5) were conducted in 1 ml of Medium 199 at 37 degrees C in the presence and absence of luteinizing hormone (LH) (0.39, 0.78, 1.56, 3.13 and 6.25 ng), progesterone (5 ng), and dehydroepiandrosterone (DHEA, 5 ng). Steroid output was measured by radioimmunoassay of incubation media. Progesterone was not produced by small follicles although they are a major source of DHEA and estradiol and a significant source of androstenedione. Output of DHEA, androstenedione and estradiol was highly stimulated by LH. The substrate for androstenedione and estradiol in small follicles is probably DHEA. Output of DHEA and androstenedione in theca cells of F2-F5 was stimulated by LH in a dose-related manner. A dose-response relationship between estradiol output and the concentration of LH in media was not apparent in theca cells from F2-F5. Steroidogenesis in theca tissue of large follicles occurs predominantly via the delta 4 pathway. The ability of these theca cells to metabolize progesterone to androstenedione is lost between 36 and 12 h before ovulation. Their ability to metabolize DHEA to androstenedione is still present 12 h before ovulation. Aromatase activity is significantly reduced between 36 and 12 h before ovulation. These data indicate that both large and small follicles can be stimulated by LH. The small follicles are the major source of estrogen. As the large yolky follicles mature, steroidogenesis shifts from the delta 5 to the delta 4 pathway. By 12 h before ovulation, the F1 follicle has lost the ability to convert progesterone to androstenedione. The inability of the largest ovarian follicle to convert progesterone to androstenedione contributes at least in part to the preovulatory increase in the plasma concentration of progesterone that generates the preovulatory LH surge by positive feedback.     

Deduction of a model for sperm storage in the oviduct of the domestic fowl (Gallus domesticus)

The mechanism of sperm storage in the fowl oviduct has remained a mystery since the 1960s, when sperm storage tubules (SST) were discovered between the shell gland and vagina. Previously, it was known that only motile sperm could ascend the vagina and enter these tubules. However, the means by which sperm resided therein was not clear. Research with computer-assisted sperm motion analysis has demonstrated that 1) seminal plasma glutamate acts as a motility agonist via N-methyl-d-aspartate receptors; 2) motility depends on extracellular Ca2+ and Na+; 3) straight-line velocity is a variable with a skewed distribution; 4) sperm cell trajectory is a function of straight-line velocity; and 5) specific inhibition of phospholipase A2 renders sperm immotile. An additional experiment demonstrated that Ca2+ acts as a second messenger and thereby modulates the content of long-chain acylcarnitine within sperm. Therefore, it is proposed that 1) the release of endogenous fatty acids fuels sperm as they ascend the vagina; (2) on entering the SST, motile sperm maintain position against a fluid current generated by SST epithelial cells; 3) resident sperm metabolize exogenous fatty acids released from lipid-laden epithelial cells; (4) motile sperm emerge from the SST when their velocity declines to a threshold at which retrograde movement begins; and 5) the skewed distribution of straight-line velocity accounts for the exponential pattern of sperm emergence from the SST. In summary, sperm residence within and emergence from the SST are phenomena most likely explicable in terms of sperm cell motility.     

A cytoarchitectonic scheme for the spinal cord of the domestic fowl, Gallus gallus domesticus: lumbar region.

In Nissl stained and silver impregnated transverse sections of the chick spinal cord it is possible to subdivide the gray matter of the lumbar region into ten cytoarchitectonically discrete regions or laminae. The laminae are basically similar in both brachial and lumbar regions of the chick cord, with minor exceptions in the dorsal horn. The laminar scheme postulated for the chick cord is , with the exception of the glycogen body and orientation of laminae 1, 2 and 3 in the dorsal horn, similar to the laminar scheme proposed by Rexed (1954) for the cat.     

Episodic growth hormone secretion in the domestic fowl (Gallus domesticus): alpha adrenergic regulation

In animals the secretion of GH is characterized by a series of spontaneous peaks. The situation in avian species, however, is unknown. The present study examines this in the domestic fowl. Blood samples were obtained via a remote catheter at 5-min intervals from young male chickens. An episodic pattern of GH secretion was observed having an interpulse interval (frequency) of approximately 1 h. Episodic GH secretion was altered by peripheral administration of drugs which influence adrenergic function. Spontaneous GH peaks were not observed following the administration of (1) bis-(4-methyl-1-homopiperazinyl-thiocarbonyl) disulfide (FLA63) or diethyldithiocarbamate (DDC) (which blocks norepinephrine (NE) and epinephrine (E) synthesis by inhibiting dopamine-beta-hydroxylase), (2) phenoxybenzamine (an alpha 1-adrenergic antagonist) and (3) clonidine (an alpha 2-adrenergic agonist). Neither alpha-methyl-p-tyrosine, which blocks dopamine (DA), NE and E synthesis, nor yohimbine, a predominantly alpha 2-antagonist could completely suppress episodic GH secretion. These data support a role for NE/E, acting via alpha adrenergic receptors, in the control of epidosic GH secretion in the domestic fowl.     

International system for standardized avian karyotypes (ISSAK): standardized banded karyotypes of the domestic fowl (Gallus domesticus)

The chicken genetic map is becoming very detailed. The genetic and physical maps need to be integrated in more detail. It is important to have a consensus banded karotype to permit this integration. An international committee met to develop a karyotype for the eight largest chromosomes and the Z and W chromosomes of the domestic fowl (Gallus domesticus). This map is presented in this report.     

Effects of genetic selection on growth rate and intestinal structure in the domestic fowl (Gallus domesticus)

1. Pieces of small intestine taken from chickens subjected previously to continuous selection, relaxed selection or no selection for rapid growth were used to estimate villus surface area and microvillus development to determine what effects genetic selection might have on factors controlling intestinal function. 2. Crypt size and the rates at which enterocytes migrated out of crypts were also measured, after injection of tritiated thymidine, to determine the time course of microvillus elongation. 3. Differences in growth rates measured between highly selected, relaxed selected or unselected birds were found to be correlated with parallel changes in villus surface area. Selection for growth did not change the density, dimensions or pattern of development of enterocyte microvilli. Microvilli did, however, produce a maximal 20-fold increase in villus surface area under all conditions. 4. Crypt size and enterocyte migration rates did not vary significantly between tissue taken from unselected and relaxed selected chickens. Tissue taken from highly selected birds had a crypt size and enterocyte migration rate 40% higher than values found for the other two groups of chickens. 5. The possibility that early genetic selection increased growth potential by uncoupling diet-induced changes on crypt hyperplasia from secondary effects on villus structure, and that later selection increased growth potential by increasing appetite, is discussed.     

Genetic-dependent alterations in adrenal stress response and adrenocortical cell function of the domestic fowl (Gallus domesticus)

Strain-dependent differences in adrenocortical function were investigated in male White Leghorn domestic fowl. Adrenocortical function of Cornell K strain (K) (genetic control), autosomal dwarf strain (ADW), and sex-linked recessive dwarf strain (SLD) was evaluated in vivo by measuring plasma corticosterone and in vitro by measuring acute (2 hr) corticosterone production by enriched adrenocortical cell populations. Regardless of strain, there was an age-dependent decrease (27-57%) in plasma corticosterone from 1 to 12 weeks of age. However, there was a tendency for plasma corticosterone values of ADW and SLD to be, respectively, greater and less than that of K. In addition, at 12 weeks of age, plasma corticosterone responses of ADW and SLD to transient heat stress (50 degrees C, 30 min) were, respectively, 22.8% greater and 15.9% less than that of K. Strain differences in adrenal weight and relative adrenal weight (mg% body wt) were also apparent. At 12 weeks of age, adrenal weights of ADW and SLD were, respectively, 33 and 42% less than that of K, whereas relative adrenal weights were, respectively, 27.6% greater and 22.4% less than that of K. In addition there were strain-dependent differences in adrenocortical function at the cellular level. Although there were no consistent strain differences in basal and maximal corticosterone production by cells, there were strain differences in cellular sensitivity to ACTH and pregnenolone. On an equal cell concentration basis, the half-maximal steroidogenic concentrations (ED50 values or effective doses for 50% maximal effect) of ACTH for ADW and SLD adrenocortical cells were, respectively, 0.23 and 2.07 times the ED50 value for K cells. In addition, the ED50 value of pregnenolone for ADW cells was 0.46 times that for K and SLD cells. Since ED50 values are a measure of cellular sensitivity (the greater the ED50 value the lesser the cellular sensitivity), the order of sensitivity to ACTH was ADW greater than K greater than SLD and the order of sensitivity to pregnenolone was ADW greater than K = SLD. However, there were no strain differences in ED50 values of 8-bromo-cyclic AMP. These data suggest that strain differences in plasma corticosterone response to stress are, in part, due to differences in relative adrenal weight and differences in adrenocortical cell function.     

Glycoconjugates of the intestinal epithelium of the domestic fowl (Gallus domesticus): a lectin histochemistry study

Summary A lectin histochemical study was performed on formalin-fixed paraffin-embedded tissues of duodenum, jejunum, ileum, caecum and colon from six fasted and six non-fasted 8-week-old chickens (Gallus domesticus). The purpose of this study was to identifyin situ the pattern of carbohydrate residues present on the luminal surface of the intestinal epithelium. Ten biotinylated lectins with different sugar specificities were used as probes, and avidin—biotin—peroxidase complex (ABC) was used as a visualant. The most significant finding was the binding pattern ofLens culinaris agglutinin to various segments of the intestines. The luminal surface of the small intestinal epithelium did not stain with this lectin. In the colon the luminal surface was lightly stained, while the caecal luminal surface was intensely stained. Throughout the intestine the luminal surface stained withCanavalia ensiformis agglutinin,Ricinus communis agglutinin-I and wheatgerm agglutinin, but it did not stain withDolichos biflorus agglutinin. These findings indicated that, throughout the intestine, the luminal surface contains glycoconjugates with eitherN- orO-linked glycoprotein, or both, with terminal non-reducing -galactosyl and sialyl residues. Furthermore, the caecal surface is rich inN-linked glycoproteins with an -(16)-linked fucosyl residue near the glycosidic linkage. The potential significance of these observations and the role of glycoconjugates in host—parasite interaction (i.e.Eimeria sp. versusGallus domesticus) are discussed.     

Demonstration of W chromosome-specific repetitive DNA sequences in the domestic fowl,Gallus g. domesticus

Evidence is presented to demonstrate the presence of W chromosome-specific repetitive DNA sequences in the female White Leghorn chicken, Gallus g. domesticus, based on two different experimental approaches. First, ³H-labelled, female chicken DNA was hybridized with excess, unlabelled, mercurated, male DNA, and unhybridized single-stranded ³H-DNA (³H-SHU-DNA) was recovered by SH-Sepharose and hydroxyapatite column chromatography. Approximately 24% of the hybridizable ³H-SHU-DNA was female-specific and localized on the W chromosome. The second approach was to examine female-specific DNA fragments among the digests of chicken DNA with various restriction endonucleases. Among them, we found that digestion with XhoI produced two prominent female-specific bands of 0.60 kb (= kilobase pairs) and 1.1 kb. The 0.60 kb fragment was isolated and ³H-labelled by nick-translation. Female-specificity of the ³H-XhoI—0.60 kb DNA was judged to be at least 95% under the conditions of hybridization with membrane filter-bound DNA. Presence of amplified XhoI—0.60 kb DNA on the W chromosome seems to be limited to different lines of G. g. domesticus and no such repeat was detected in three species belonging to other genera in the order Galliformes and in three species belonging to other avian orders.     

Localization of avian LHRH-immunoreactive neurons in the hypothalamus of the domestic fowl,Gallus domesticus,and the Japanese quail,Coturnix coturnix

The localization of LHRH-containing perikarya and nerve fibers in the hypothalami of the domestic fowl and Japanese quail was investigated by means of the specific immunoperoxidase ABC method, using antisera against chicken LHRH-I ([Gln8]-LHRH), chicken GnRH-II ([His5-Trp7-Tyr8]-LHRH[2-10]) and mammalian LHRH ([Arg8]-LHRH). Chicken LHRH-I-immunoreactive perikarya were sparsely scattered in the nucleus preopticus periventricularis (POP), nucleus filiformis (FIL) and nucleus septalis medialis (SM), and in bilateral bands extending from these nuclei into the septal area in both species. A few reactive perikarya were also observed in the nucleus accumbens (Ac) and lobus parolfactorius (LPO). Numerous cLHRH-I-immunoreactive fibers were widely scattered in the preoptic, septal and tuberal areas, and were densely concentrated in the external layer of the median eminence and in organum vasculosum of the lamina terminalis (OVLT) in both species. Anti-mammalian LHRH serum cross-reacted weakly with perikarya and fibers immunoreactive to anti-cLHRH-I serum in normal chicken and quail. Anti-cGnRH-II[2-10] serum immunoreacted with magnocellular neurons distributed in the rostral end of the mesencephalon along the midline close to the nervus oculomotorius (N III). These perikarya were apparently different from cLHRH-I immunoreactive neurons. No immunoreactive cells and fibers against anti-cGnRH-II[2-10] were observed in the hypothalamus and median eminence of the chicken or quail. Anti-cGnRH-II[2-10] bound specifically with cGnRH-II.(ABSTRACT TRUNCATED AT 250 WORDS)     

Circulating concentrations of inhibin-related proteins during the ovulatory cycle of the domestic fowl (Gallus domesticus) and after induced cessation of egg laying

Circulating inhibin A, inhibin B, activin A, total immunoreactive inhibin alpha-subunit (ir-alpha inhibin), LH, FSH and progesterone concentrations were measured throughout the normal ovulatory cycle and after cessation of egg laying induced by feed restriction to investigate the potential involvement of inhibins and activins in the ovulatory cycle of the domestic hen. Plasma inhibin A varied significantly (P < 0.05) during the ovulatory cycle; the concentration was highest at the preovulatory LH surge and reached a nadir 10 h later, at about the time the F(2) follicle makes the transition to become the new F(1) follicle. Plasma FSH concentrations did not change significantly throughout the cycle and showed no correlation with inhibin A. Total ir-alpha inhibin concentrations were much higher than those of inhibin A at all stages of the ovulatory cycle and showed no correlation with inhibin A or FSH. Plasma concentrations of inhibin B and of activin A were below the detection limit of the assays in all plasma samples analysed. In the feed restriction study, plasma inhibin A and total ir-alpha inhibin showed little change until the last day of oviposition (day 0) after which they fell significantly (P < 0.05) and remained low to the end of the experiment (approximately 70-78% decrease relative to day -4). Conversely, plasma FSH increased after cessation of laying and was significantly higher (P < 0.05) from day 3 to the end of the study (approximately 50% increase on day 6 relative to day -4). Plasma FSH values were negatively correlated with inhibin A (r = -0.39; P < 0.005) and total ir-alpha inhibin (r = -0.36; P < 0.005). Plasma LH and progesterone also decreased (P < 0.05) during feed restriction. The decrease in LH preceded the terminal oviposition and the associated fall in inhibin A by 2 days; there was a positive correlation between LH and inhibin A (r = 0.35; P < 0.005). Taken together these findings support (i) a role for LH in promoting inhibin A secretion by preovulatory follicles and (ii) an endocrine role for inhibin A secreted by preovulatory follicles in the maintenance of tonic FSH secretion in laying hens.     

Observations on the cyto -morphological changes in the anterior pituitary of the Indian domestic fowl Gallus domesticus, during various growth phases including laying and broody periods

In the following account, detailed investigations are carried out on the cyto-morphological changes in the anterior pituitary (adenohypophysis) of the Indian domestic fowl (Desi fowl) Gallus domesticus during various growth phases including laying and broody periods.     

Early nuclear events of in vitro fertilization in the domestic fowl (Gallus domesticus)

In vitro fertilization in the domestic fowl (Gallus domesticus) was investigated by observation of the early nuclear events. Ova retrieved from the fimbria following ovulation were inseminated in vitro with 10(6)-10(7) spermatozoa in Dulbecco's modified Eagle's medium (DMEM) for 10 min and then further incubated in DMEM + albumen for 1, 2, 3, or 4 hr. These eggs were histologically examined by epifluorescent microscopy after staining with 4',6'-diamidino-2-phenylindole (DAPI). Nuclei of spermatozoa at various stages of transformation were observed in the ova incubated for 1-3 hr. Close pairing of two pronuclei, presumed to be male and female juxtaposition, was detected in ova incubated for 4 hr. These data provide direct evidence for the in vitro fertilization of fowl eggs and suggested that the early process of in vitro fertilization is comparable to that of in vivo fertilization.     

The neuronal and extra-neuronal localisations of biogenic amines in the cervical region of the domestic fowl (Gallus Gallus domesticus L.)

Summary The Falck-Hillarp technique has been used to demonstrate the neuronal and extra-neuronal localisations of biogenic amines in the cervical region of the domestic fowl. Adrenergic cell bodies were found in the superior cervical ganglion and in the ganglia of the cervical paravertebral chain. The axons of the latter ran into the corresponding spinal nerves and thus to the periphery. Very few adrenergic fibres were found in the interganglionic portions of the cervical paravertebral chain. The precarotid branch of the glossopharyngeal nerve, and the vagus nerve, below its junction with the former, contained numbers of adrenergic fibres. The retrocarotid nerve-trunk from the superior cervical ganglion was composed of adrenergic fibres. With the exception of the parathyroid gland, the adrenergic nerves seen in the branchial derivatives (thymus, thyroid and ultimobranchials) appeared to be associated with blood vessels. Under normal conditions the cells of the ultimobranchial body were nonfluorescent, but after injection of 6-hydroxydopamine the cells were brightly fluorescent. The carotid body was devoid of adrenergic nerves other than those with blood vessels, but the cells of the carotid body were brightly fluorescent. Various fluorescent cell types were found throughout the cervical region, particularly in association with the vasculature. I should like to thank Prof. G. Burnstock (Department of Zoology, Melbourne University) in whose department this work was carried out and Dr. R. D. Hodges (Wye College, London University) for his indispensable advice on the disposition of the avian ultimobranchial body. The author held a Postdoctoral Research Fellowship of the National Heart Foundation of Australia during part of this study.     

Synthetic human pancreatic growth hormone releasing factor (GRF) stimulates growth hormone secretion in the domestic fowl (Gallus domesticus)

Synthetic human pancreatic Growth Hormone-Releasing Factor (hpGRF) elevated the plasma concentration of growth hormone (GH) in young and adult domestic fowl. This in vivo effect of hpGRF appeared to be largely similar for both the 32 amino-acid (hpGRF 1-32) or 40 amino-acid (hpGRF 1-40) polypeptide, although the effect of hpGRF 1-32 was more prolonged than that of hpGRF 1-40 in adult domestic fowl. The increase in plasma GH concentrations following hpGRF administration (10 micrograms/kg) was somewhat greater in young than adult chickens (the increase in plasma concentration of GH being 230 ng/ml at 1 week old, 282 ng/ml at 6 week old, 241 ng/ml at 10 weeks and 150 ng/ml in adults). In the adult domestic fowl hpGRF stimulated a greater increase in the plasma concentration of GH than did thyrotropin-releasing hormone (TRH). However in the young chicks TRH was more active. The in vitro release of GH from dispersed chicken pituitary cells was elevated by hpGRF (1-32) and hpGRF (1-40).     

Effects of corticosteroids on short-circuit current across the cecum of the domestic fowl,Gallus domesticus

Summary Both avian corticosteroid hormones, aldosterone and corticosterone, increased short-circuit current across the wall of the ceca of the domestic fowl (Gallus domesticus) in vitro. About 80% of this short-circuit current was inhibited by the Na-channel blocking drug amiloride. Corticosterone was about ten times less potent than aldosterone in increasing short-circuit current and it exerted a similar maximal effect. Cortisol (an endogenous corticosteroid hormone in mammals but not birds) was about ten times less potent than corticosterone and this difference appeared to reflect the presence of the 17-OH group in cortisol. Carbenoxolene, which inhibits 11-hydroxysteroid dehydrogenase, increased the effect of corticosterone. This effect is consistent with inhibition of the metabolism of corticosterone to 11-dehydrocorticosterone. The latter was found to be about 100 times less potent than corticosterone. The effects of both aldosterone and corticosterone (also dexamethasone) were abolished by the mineralocorticoid receptor antagonist spironolactone. The results suggest that corticosterone has an effect similar to aldosterone but in vivo its action may be depressed by the activity of 11-hydroxysteroid dehydrogenase. The sensitivity of the cecal preparations to corticosterone indicates that this hormone could contribute to the regulation of transcecal Na transport (absorption) in vivo.Abbreviations 11-HSD 11-Hydroxysteroid dehydrogenase - sc short-circuit current - KRB Krebs bicarbonate solution