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gonads

gonads Sentence Examples

  • (3) The gonads, whether formed in the polyp or the medusa, are developed in the ectoderm.

  • Hence the gonads are found on the manubrium in Anthomedusae generally; on the base of the manubrium, or under the gastral pouches, or in both these situations (Octorchidae), or under the radial canals, in Trachomedusae; under the gastral pouches or radial canals, in Narcomedusae.

  • g, Gonads.

  • Thus the gonads are covered over by at least four layers of epithelium, and since these are unnecessary, presenting merely obstacles to the dehiscence of the gonads, they gradually undergo reduction.

  • 41, F, G, H), and consists of the spadix bearing the gonads covered by a single layer of ectoderm (ex.), with or without the addition of an ectotheca.

  • It has been maintained that the gonads of Hydra represent sporosacs or gonophores greatly reduced, with the last traces of medusoid structure completely obliterated.

  • There is, however, no evidence whatever for this, the gonads of Hydra being purely ectodermal structures, while all medusoid gono phores have an endodermal portion.

  • In some Leptomedusae the gonads are formed on the radial canals and form protruding masses resembling sporosacs superficially, but not in structure.

  • The buds of Margellium are produced on the manubrium in each of the four interradii, and they arise from the ectoderm, that is to say, the germinal epithelium, which later gives rise to the gonads.

  • The gonads are borne on the manubrium, either forming a continuous ring (Codonid type), or four masses or pairs of masses (Oceanid type).

  • - Tropho- some unknown; gonosome, free medusae, with deep, bell-shaped umbrella, with interradial gonads on the base of the stomach, with branched radial canals, and correspondingly numerous hollow tentacles.

  • Trophosome (only known in one genus), polyps with two tentacles forming a creeping colony; gonosome, free medusae with four, six or more radial canals, giving off one or more lateral branches which run to the margin of the umbrella, with the stomach produced into four, six or more lobes, upon which the gonads are developed; the mouth with four lips or with a folded margin; the tentacles simple, arranged evenly round the margin of the umbrella.

  • - Trophosome only known in one genus (Thaumantias), similar to that of the Eucopidae; gonosome, free medusae with otocysts inconspicuous or absent, with usually four, sometimes eight, rarely more than eight, radial canals, simple and unbranched, along which the gonads are developed, with numerous tentacles bearing ocelli and with marginal sense-clubs.

  • - Trophosome unknown; gonosome, free medusae, with four or six radial canals, bearing the gonads, with numerous tentacles, between which occur sense-clubs, without otocysts.

  • bearing gonads on the main canal, but not on the branches, with numerous hollow tentacles bearing ocelli, and without otocysts.

  • The gonads are de

  • The manubrium bearing the gonads is mouthless, and the umbrella is without tentacles, sense-organs, velum or radial canals.

  • not lobed or indented; tentaculocysts usually enclosed in vesicles; gonads on the radial canals.

  • The gonads are on the radial canals or on the stomach (Ptychogastridae), and each gonad may be divided into two by a longitudinal sub-umbral muscle-tract.

  • - Four radial canals, four gonads; stomach not prolonged into the manubrium, which is relatively short; tentaculocysts free.

  • Olindiadae, with four radial canals and four gonads; manubrium short; ring-canals giving off blind centripetal canals; tentaculocysts enclosed.

  • Eight radial canals, eight gonads, stomach not prolonged into manubrium; tentaculocysts enclosed.

  • Eight radial canals, two, four or eight gonads; tentacles numerous; tentaculocysts free; stomach prolonged into manubrium.

  • 65), &c., with eight gonads; Stauraglaura with four; Persa with two.

  • Amphogona, hermaphrodite, with male and female gonads on alternating radial canals.

  • Four or six radial canals; gonads band-like; stomach prolonged into a manubrium of great length; tentaculocysts enclosed.

  • - Margin of the umbrellalobed, tentacles arising from the ex-umbrella at some distance from the margin; tentaculocysts exposed, not enclosed in vesicles; gonads on the sub-umbral floor of the stomach or of the gastric pouches.

  • Cunoctantha fowleri Browne, buds are formed from the sub-umbrella on the under side of the stomach pouches, where later the gonads are developed.

  • The male gonads are carried on the radial canals.

  • It buds medusae from the margin of the mouth in May and June, and in August and September the gonads' are formed in the place where the buds arose.

  • In these features, and in the fact that the gonads are local proliferations of the coelomic epithelium, which have undergone no further changes in the simpler forms, the coelom of this group shows in a particularly clear fashion the general characters of the coelom in the higher Metazoa.

  • Among the simpler Chaetopoda the coelom retains the character of a series of paired chambers, showing the above relations to the exterior and to the gonads.

  • To this pericardial coelom is frequently added a gonocoel enclosing the gonads and the funnels of their ducts.

  • Gonads not so restricted in position as in Oligochaets, and often more abundant; the individuals usually unisexual.

  • They contrast with those of the Oligochaeta and Hirudinea by reason of their frequently close association with the gonads, the same organ sometimes serving the two functions of excretion and conveyance of the ova and spermatozoa out of the body.

  • It seems that the posterior nephridia are mainly gonad ducts, and the gonads are developed in close association with the funnels.

  • In Syllis there is also a "Heterosyllid" form in which the gonads are limited to a posterior region of the body which is further marked off from the anterior non-sexual segments by the oak-like setae.

  • Gonads limited in number of pairs, testes and ovaries always present in the same individual.

  • Gonads and Gonad Ducts.

  • The gonads are, moreover, limited and fixed in numbers, and are practically invariably attached to the intersegmental septa, usually to the front septum of a segment, more rarely to the posterior septum.

  • The Oligochaeta contrast with the Polychaeta in the general presence of outgrowths of the septa in the genital segments, which are either close to, or actually involve, the gonads, and into which may also open the funnels of the gonad ducts.

  • The gonad ducts are male and female, and open opposite to or, rarely, alongside of the gonads, whose products they convey to the exterior.

  • Their position varies, but is constant for the species, and they are rarely found behind the gonads.

  • The intervening segments contain the genitalia, which are on the Oligochaeta plan in that the gonads are independent of their ducts and that there are special spermathecae, one pair.

  • In the middle of the body, where the limits of the somites can be checked by a comparison with the arrangement of the nephridia and the gonads, and where the ganglia are quite distinct and separated by long connectives, each ganglion is seen to consist of six masses of cells enclosed by capsules and to give off three nerves on each side.

  • The gonads and their ducts in the Hirudinea invariably form a closed system of cavities entirely shut off from the coelom in which they lie.

  • The two ducts continuous with the gonads open by a common vagina on to the exterior behind the male pores.

  • The gonads develop (0.

  • It is to be noted that the Hirudinea differ from the Oligochaeta in that the male pore is in advance of the gonads (except in Acanthobdella, which here, as in so many points, approximates to the Oligochaeta), whereas in Oligochaeta that pore is behind the gonads (again with an exception, Aliurus).

  • Originally the gonads opened into the kidneys.

  • - Follicles of the hermaphrodite gonads of Euthyneurous Gastropods.

  • Both male and female gonads consist of more or less lobulated hollow sacs connected with the epidermis by short ducts.

  • These folds are called the genital pleurae because they contain the bulk of the gonads.

  • is said to produce fully developed gonads, and if kept in aquaria with Tubifex, the number of infected worms steadily increases, a fact pointing to the whole cycle being passed through, without the intermediation of a vertebrate host.

  • We therefore regard the body of a Cestode as a single organism within which the gonads have become segmented, and the segmentation of the body as a secondary phenomenon associated with diffuse osmotic feeding in the narrow intestinal canal.

  • These organisms live in cockles, oysters and other lamellibranchs and they so affect the gonads of these molluscs as to castrate and sterilize their host.

  • The body contains in miniature all the organs of the adult fluke, including the gonads and in addition "eye-spots," a stylet, rod-cells and cystogenous cells.

  • Gonads.

  • The gonads or generative organs may be produced either in the ectoderm or the endoderm.

  • When the gonads are endodermal, they are formed on the floor of the stomach; when ectodermal (G, see fig.

  • A pair of genital apertures, connected by genital ducts with the paired gonads, are found right and left near the nephridial pores, except in a few cases where the genital duct joins that of the renal organ (Spondylus).

  • The gonads of Anodonta are placed in distinct male and female individuals.

  • The tion of liquid between the gonads themselves are extremely outer and the invaginated simple arborescent glands which cells.

  • ducts, one right and one left, continu ous with the tubular branches of the gonads.

  • In the most primitive Lamellibranchs there is no separate generative aperture but the gonads discharge into the renal cavity, as in Patella among Gastropods.

  • In them the foot has a flat ventral surface used for creeping, as in Gastropods, the byssus gland is but slightly developed, the pleural ganglia are distinct, there is a relic of the pharyngeal cavity, in some forms with a pair of glandular sacs, the gonads retain their primitive connexion with the renal cavities, and the otocysts are open.

  • The gonads open into the kidneys and the right gonad extends into the mantle.

  • Gonads generally extend into mantle and open at sides of kidneys.

  • Gonads contained in the visceral mass and generally open into renal.

  • The gonads always have their own proper external apertures.

  • In Mollusca the coelom is reduced and consists of two parts, the pericardial cavity which surrounds the heart, and the cavity of the gonads or generative organs.

  • In the majority of Mollusca the gonads are provided with a pair of ducts of their own.

  • In the most primitive forms of several classes there are no distinct genital ducts, the gonads when mature discharging into or through the kidneys.

  • The grounds for this view are the radial symmetry of several Polyclads and the supposed origin of gonads and excretory flame-cells from the walls of gut, the occurrence of nematocysts in Anonymus, one of the most radially constructed Polyclads, and lastly the presence of two peculiar animals Ctenoplana and Coeloplana, which suggests a transition from Ctenophora to Polyclads.

  • The study of Rhabdocoels (7) has led to the important discovery that the rudiment of the gonads and that of the pharynx are the first organs to appear, and that the alimentary sac arises independently of them.

  • As in other molluscs the coelom is represented by a large pericardial cavity, situated above the intestine posteriorly, and a generative sac which is single and median and situated in front of the pericardium, except in the Nuttalochiton hyadesi, where the gonads are in a similar position, but are paired.

  • The gonads originate by proliferation of the anterior wall of the pericardium.

  • The gonads are paired and hermaphrodite, they form a pair of anterior prolongations of the pericardium, extending nearly to the anterior end of the body.

  • Coelom, Gonads and Excretory Organs.

  • Heteropleuron Kirkaldy, with unilateral gonads.

  • (Slightly altered from Kirkaldy.) rm and lm, Right and left metapleur; at, atriopore; an, anus; e, " eyespot" at anterior end of neurochord projecting beyond the myotomes (my); n, notochord; rgo, gonads of right side only showing through by transparency; go 20, the last gonad; dfr, dorsal fin with fin chambers and fin rays; vfc, ventral fin chambers.

  • (Original drawings.) (I) Lateral view of adult, to show general form, the myomeres, fin rays and gonads.

  • A, Oral tentacles (28 to 32 in full-grown animals, 20 to 24 in half-grown specimens); B, praeoral hood or praeoral epipleur; C, plicated ventral surface of atrial chamber; D l, D 17, D26, gonads, twenty-six pairs, coincident with myotomes io to 36; E, metapleur or lateral ridge on atrial epipleur; F, atripore, coincident with myotome 36; G', G ' 5, G34, double ventral fin rays, extending from myotomes 37 to 52, but having no numerical relation to them; H, position of anus, between myotomes 51 and 52; I, notochord, projecting beyond myotomes; K7, K27, K62, myotomes or muscular segments of body-wall, 62 in number; L '°°, L230, L253, dorsal fin rays, about 250 in number, the hard substance of the ray being absent at the extreme ends of the body (these have no constant numerical relation to the myomeres); M, notochord as seen through the transparent myotomes, the thin double-lined spaces being the connective-tissue septa and the broader spaces the muscular tissue of the myotomes; N, position of brown funnel of left side (atrio-coelomic canal); 0, nerve tube resting on notochord.

  • (After Rathke, slightly altered.) m, Mouth appearing as an elongated slit when relaxed (as in the lamprey); p, perforated pharynx; e, endostyle; g, gonads; 1, liver; at, level of atriopore; intestine; an, anus.

  • ==Reproductive System== The sexes are separate, and the male or female gonads, which are exactly similar in outward appearance, occur as a series of gonadic pouches projecting into the atrial cavity at the base of the myotomes (figs.

  • The gonads are formed in the endoderm (hence " Entocarpeae "), and the generative products are shed into the gastric cavity and pass to the exterior by way of the mouth.

  • On the floor of the stomach are borne the conspicuous gonads (ov), and also tentacle-like processes termed gastric filaments or phacellae, projecting into the cavity of the stomach.

  • The gonads are folds of the endoderm containing generative cells, and are primitively four in number, situated interradially, but each gonad may be divided into two by the partition which separates two adjacent lobes of the stomach, that is to say, by one of the areas of concrescence between exumbral and subumbral endoderm, whence arises a condition with eight gonads which is by no means uncommon.

  • They serve probably for the aeration of the gonads by admitting to their vicinit y water with its dissolved oxygen; they never serve as genital ducts, since the generative products are always dehisced into the stomach and pass out by the mouth.

  • The eight adradial gonads on the subumbral walls of the four radial pouches, representing primitively four horse-shoeshaped gonads each divided into two by an interradial septum.

  • shoe-shaped gonads (ov) mark, Oral arms. ing four stomach-pouches, b t tentacles.

  • The diagnostic features of the class Scyphozoa thus constituted are supposed to be (I) an ectodermal oesophagus or stomodaeum, (2) a gastric cavity subdivided by mesenteries, (3) gonads formed in the endoderm.

  • There remains only the third feature, the endodermal gonads, as an argument for uniting the Scyphomedusae with the Anthozoa, against which must be set all the peculiarities of medusan organization in which the Scyphomedusae resemble the Hydromedusae.

  • ring-canal absent); gonads divided each into two by the septa, hence eight in number; subgenital pits small or absent.

  • Eight gonads.

  • Sessile, stalked, with eight shallow marginal lobes bearing one or more rows of tentacles; without tentaculocysts; with four gonads.

  • The gonads, as in other Arthropoda, are hollow saccular organs, the cavity communicating with the efferent ducts.

  • 4 organs or gonads are borne on the mesenteries, the germinal cells being derived from the inner layer or endoderm.

  • go, Gonads.

  • short, the sulco-lateral and sulculo-lateral pairs are a little longer, but the two transverse are very large and are the only mesenteries which bear gonads.

  • bear gonads.

  • - Radial symmetry has affected neither food-grooves nor thecal plates; nor, probably, nerves, ambulacral vessels, nor gonads.

  • - Radial symmetry affects the food-grooves and, in the more advanced families, the thecal plates; probably also the nerves and ambulacral vessels, but not the gonads.

  • - Pentamerous symmetry affects the foodgrooves and thecal plates; probably also the nerves and ambulacral vessels, but not the gonads.

  • - Radial symmetry affects the food-grooves, and by degrees the thecal plates connected therewith, but not the interradial thecal plates; probably also the nerves and ambulacral vessels, but not the gonads.

  • The gonads are not radiately disposed.

  • churning the stomach while stirring the gonads.

  • They are derived from the epithelial sex cords of the developing gonads.

  • This echinoderm is a simultaneous hermaphrodite (male gonads and mature eggs occurring together ).

  • Current work includes: assessing the contribution of dietary lipids in sea urchin gonads from sub-tidal and intertidal areas of Loch Creran.

  • (3) The gonads, whether formed in the polyp or the medusa, are developed in the ectoderm.

  • Hence the gonads are found on the manubrium in Anthomedusae generally; on the base of the manubrium, or under the gastral pouches, or in both these situations (Octorchidae), or under the radial canals, in Trachomedusae; under the gastral pouches or radial canals, in Narcomedusae.

  • The gonads (g) are produced on the manubrium, which has a hollow endodermal axis, termed the spadix (sp.), in open communication with the coenosarc of the polyp-colony and serving for the nutrition of the generative cells.

  • g, Gonads.

  • Next the opening of the umbrella closes up completely and disappears, so that the sub-umbral cavity forms a closed space surrounding the manubrium, on which the gonads are developed; such a condition is seen in the male gonophore of Cladocoryne and in Garveia (fig.

  • Thus the gonads are covered over by at least four layers of epithelium, and since these are unnecessary, presenting merely obstacles to the dehiscence of the gonads, they gradually undergo reduction.

  • 41, F, G, H), and consists of the spadix bearing the gonads covered by a single layer of ectoderm (ex.), with or without the addition of an ectotheca.

  • The spadix, as the organ of nutrition for the gonads, may be developed in various ways, being simple (fig.

  • It has been maintained that the gonads of Hydra represent sporosacs or gonophores greatly reduced, with the last traces of medusoid structure completely obliterated.

  • There is, however, no evidence whatever for this, the gonads of Hydra being purely ectodermal structures, while all medusoid gono phores have an endodermal portion.

  • In some Leptomedusae the gonads are formed on the radial canals and form protruding masses resembling sporosacs superficially, but not in structure.

  • the layer in which, in Hydromedusae, the generative cells are lodged; and in some cases the buds are produced in the exact spot in which later the gonads appear.

  • The buds of Margellium are produced on the manubrium in each of the four interradii, and they arise from the ectoderm, that is to say, the germinal epithelium, which later gives rise to the gonads.

  • If we accept the view that Hydra is a true sexual polyp, and that its gonads are not gonophores (i.e.

  • The gonads are borne on the manubrium, either forming a continuous ring (Codonid type), or four masses or pairs of masses (Oceanid type).

  • - Tropho- some unknown; gonosome, free medusae, with deep, bell-shaped umbrella, with interradial gonads on the base of the stomach, with branched radial canals, and correspondingly numerous hollow tentacles.

  • Trophosome (only known in one genus), polyps with two tentacles forming a creeping colony; gonosome, free medusae with four, six or more radial canals, giving off one or more lateral branches which run to the margin of the umbrella, with the stomach produced into four, six or more lobes, upon which the gonads are developed; the mouth with four lips or with a folded margin; the tentacles simple, arranged evenly round the margin of the umbrella.

  • - Trophosome only known in one genus (Thaumantias), similar to that of the Eucopidae; gonosome, free medusae with otocysts inconspicuous or absent, with usually four, sometimes eight, rarely more than eight, radial canals, simple and unbranched, along which the gonads are developed, with numerous tentacles bearing ocelli and with marginal sense-clubs.

  • - Trophosome unknown; gonosome, free medusae, with four or six radial canals, bearing the gonads, with numerous tentacles, between which occur sense-clubs, without otocysts.

  • bearing gonads on the main canal, but not on the branches, with numerous hollow tentacles bearing ocelli, and without otocysts.

  • The gonads are de

  • The manubrium bearing the gonads is mouthless, and the umbrella is without tentacles, sense-organs, velum or radial canals.

  • not lobed or indented; tentaculocysts usually enclosed in vesicles; gonads on the radial canals.

  • The gonads are on the radial canals or on the stomach (Ptychogastridae), and each gonad may be divided into two by a longitudinal sub-umbral muscle-tract.

  • - Four radial canals, four gonads; stomach not prolonged into the manubrium, which is relatively short; tentaculocysts free.

  • Olindiadae, with four radial canals and four gonads; manubrium short; ring-canals giving off blind centripetal canals; tentaculocysts enclosed.

  • Eight radial canals, eight gonads, stomach not prolonged into manubrium; tentaculocysts enclosed.

  • Eight radial canals, two, four or eight gonads; tentacles numerous; tentaculocysts free; stomach prolonged into manubrium.

  • 65), &c., with eight gonads; Stauraglaura with four; Persa with two.

  • Amphogona, hermaphrodite, with male and female gonads on alternating radial canals.

  • Four or six radial canals; gonads band-like; stomach prolonged into a manubrium of great length; tentaculocysts enclosed.

  • - Margin of the umbrellalobed, tentacles arising from the ex-umbrella at some distance from the margin; tentaculocysts exposed, not enclosed in vesicles; gonads on the sub-umbral floor of the stomach or of the gastric pouches.

  • Cunoctantha fowleri Browne, buds are formed from the sub-umbrella on the under side of the stomach pouches, where later the gonads are developed.

  • The male gonads are carried on the radial canals.

  • It buds medusae from the margin of the mouth in May and June, and in August and September the gonads' are formed in the place where the buds arose.

  • In these features, and in the fact that the gonads are local proliferations of the coelomic epithelium, which have undergone no further changes in the simpler forms, the coelom of this group shows in a particularly clear fashion the general characters of the coelom in the higher Metazoa.

  • Among the simpler Chaetopoda the coelom retains the character of a series of paired chambers, showing the above relations to the exterior and to the gonads.

  • To this pericardial coelom is frequently added a gonocoel enclosing the gonads and the funnels of their ducts.

  • That these organs in Polychaeta serve for the removal of the generative products to the exterior is proved not only by the correspondence in number to them of the gonads, but by actual observation of the generative products in transit.

  • Gonads not so restricted in position as in Oligochaets, and often more abundant; the individuals usually unisexual.

  • They contrast with those of the Oligochaeta and Hirudinea by reason of their frequently close association with the gonads, the same organ sometimes serving the two functions of excretion and conveyance of the ova and spermatozoa out of the body.

  • It seems that the posterior nephridia are mainly gonad ducts, and the gonads are developed in close association with the funnels.

  • In Syllis there is also a "Heterosyllid" form in which the gonads are limited to a posterior region of the body which is further marked off from the anterior non-sexual segments by the oak-like setae.

  • Gonads limited in number of pairs, testes and ovaries always present in the same individual.

  • Gonads and Gonad Ducts.

  • The gonads are, moreover, limited and fixed in numbers, and are practically invariably attached to the intersegmental septa, usually to the front septum of a segment, more rarely to the posterior septum.

  • The segments occupied by the gonads are fixed, and are for earthworms invariably X, XI.

  • The Oligochaeta contrast with the Polychaeta in the general presence of outgrowths of the septa in the genital segments, which are either close to, or actually involve, the gonads, and into which may also open the funnels of the gonad ducts.

  • The gonad ducts are male and female, and open opposite to or, rarely, alongside of the gonads, whose products they convey to the exterior.

  • Their position varies, but is constant for the species, and they are rarely found behind the gonads.

  • The intervening segments contain the genitalia, which are on the Oligochaeta plan in that the gonads are independent of their ducts and that there are special spermathecae, one pair.

  • In the middle of the body, where the limits of the somites can be checked by a comparison with the arrangement of the nephridia and the gonads, and where the ganglia are quite distinct and separated by long connectives, each ganglion is seen to consist of six masses of cells enclosed by capsules and to give off three nerves on each side.

  • The gonads and their ducts in the Hirudinea invariably form a closed system of cavities entirely shut off from the coelom in which they lie.

  • The two ducts continuous with the gonads open by a common vagina on to the exterior behind the male pores.

  • The gonads develop (0.

  • It is to be noted that the Hirudinea differ from the Oligochaeta in that the male pore is in advance of the gonads (except in Acanthobdella, which here, as in so many points, approximates to the Oligochaeta), whereas in Oligochaeta that pore is behind the gonads (again with an exception, Aliurus).

  • Originally the gonads opened into the kidneys.

  • - Follicles of the hermaphrodite gonads of Euthyneurous Gastropods.

  • Both male and female gonads consist of more or less lobulated hollow sacs connected with the epidermis by short ducts.

  • These folds are called the genital pleurae because they contain the bulk of the gonads.

  • is said to produce fully developed gonads, and if kept in aquaria with Tubifex, the number of infected worms steadily increases, a fact pointing to the whole cycle being passed through, without the intermediation of a vertebrate host.

  • The Monozoa are unsegmented; the Ligulidce have segmented gonads and gonopores without any trace of somatic metamerization except secondary excretory pores in addition to the usual terminal one; the remaining Cestodes are unisegmental only in their larval stage, and all of them show in their later stages repetition of the reproductive organs and of the musculature.

  • In addition, some show duplication of the gonads and of their ducts, so that we find both transverse and longitudinal repetition of these organs, without corresponding multiplication of the nervous ganglia mesenchyma, or excretory opening.

  • We therefore regard the body of a Cestode as a single organism within which the gonads have become segmented, and the segmentation of the body as a secondary phenomenon associated with diffuse osmotic feeding in the narrow intestinal canal.

  • The origin of the repetition of the gonads has yet to be investigated.

  • The blood of most species behaves differentially towards precipitants, and it is therefore conceivable that when blood is used as food and is elaborated into special compounds for the nutrition of the reproductive organs of a parasite, these specific or larger differences in the blood of animal hosts may prevent the ripening of the gonads of a widely diffused parasite and only one particular kind of blood prove suitable.

  • These organisms live in cockles, oysters and other lamellibranchs and they so affect the gonads of these molluscs as to castrate and sterilize their host.

  • The body contains in miniature all the organs of the adult fluke, including the gonads and in addition "eye-spots," a stylet, rod-cells and cystogenous cells.

  • The gonads or generative organs may be produced either in the ectoderm or the endoderm.

  • When the gonads are endodermal, they are formed on the floor of the stomach; when ectodermal (G, see fig.

  • A pair of genital apertures, connected by genital ducts with the paired gonads, are found right and left near the nephridial pores, except in a few cases where the genital duct joins that of the renal organ (Spondylus).

  • The gonads of Anodonta are placed in distinct male and female individuals.

  • The tion of liquid between the gonads themselves are extremely outer and the invaginated simple arborescent glands which cells.

  • ducts, one right and one left, continu ous with the tubular branches of the gonads.

  • In the most primitive Lamellibranchs there is no separate generative aperture but the gonads discharge into the renal cavity, as in Patella among Gastropods.

  • In them the foot has a flat ventral surface used for creeping, as in Gastropods, the byssus gland is but slightly developed, the pleural ganglia are distinct, there is a relic of the pharyngeal cavity, in some forms with a pair of glandular sacs, the gonads retain their primitive connexion with the renal cavities, and the otocysts are open.

  • The gonads open into the kidneys and the right gonad extends into the mantle.

  • Gonads generally extend into mantle and open at sides of kidneys.

  • Gonads contained in the visceral mass and generally open into renal.

  • The gonads always have their own proper external apertures.

  • In Mollusca the coelom is reduced and consists of two parts, the pericardial cavity which surrounds the heart, and the cavity of the gonads or generative organs.

  • In the majority of Mollusca the gonads are provided with a pair of ducts of their own.

  • In the most primitive forms of several classes there are no distinct genital ducts, the gonads when mature discharging into or through the kidneys.

  • The grounds for this view are the radial symmetry of several Polyclads and the supposed origin of gonads and excretory flame-cells from the walls of gut, the occurrence of nematocysts in Anonymus, one of the most radially constructed Polyclads, and lastly the presence of two peculiar animals Ctenoplana and Coeloplana, which suggests a transition from Ctenophora to Polyclads.

  • The study of Rhabdocoels (7) has led to the important discovery that the rudiment of the gonads and that of the pharynx are the first organs to appear, and that the alimentary sac arises independently of them.

  • As in other molluscs the coelom is represented by a large pericardial cavity, situated above the intestine posteriorly, and a generative sac which is single and median and situated in front of the pericardium, except in the Nuttalochiton hyadesi, where the gonads are in a similar position, but are paired.

  • The gonads originate by proliferation of the anterior wall of the pericardium.

  • The gonads are paired and hermaphrodite, they form a pair of anterior prolongations of the pericardium, extending nearly to the anterior end of the body.

  • Coelom, Gonads and Excretory Organs.

  • Heteropleuron Kirkaldy, with unilateral gonads.

  • (Slightly altered from Kirkaldy.) rm and lm, Right and left metapleur; at, atriopore; an, anus; e, " eyespot" at anterior end of neurochord projecting beyond the myotomes (my); n, notochord; rgo, gonads of right side only showing through by transparency; go 20, the last gonad; dfr, dorsal fin with fin chambers and fin rays; vfc, ventral fin chambers.

  • (Original drawings.) (I) Lateral view of adult, to show general form, the myomeres, fin rays and gonads.

  • A, Oral tentacles (28 to 32 in full-grown animals, 20 to 24 in half-grown specimens); B, praeoral hood or praeoral epipleur; C, plicated ventral surface of atrial chamber; D l, D 17, D26, gonads, twenty-six pairs, coincident with myotomes io to 36; E, metapleur or lateral ridge on atrial epipleur; F, atripore, coincident with myotome 36; G', G ' 5, G34, double ventral fin rays, extending from myotomes 37 to 52, but having no numerical relation to them; H, position of anus, between myotomes 51 and 52; I, notochord, projecting beyond myotomes; K7, K27, K62, myotomes or muscular segments of body-wall, 62 in number; L '°Â°, L230, L253, dorsal fin rays, about 250 in number, the hard substance of the ray being absent at the extreme ends of the body (these have no constant numerical relation to the myomeres); M, notochord as seen through the transparent myotomes, the thin double-lined spaces being the connective-tissue septa and the broader spaces the muscular tissue of the myotomes; N, position of brown funnel of left side (atrio-coelomic canal); 0, nerve tube resting on notochord.

  • (After Rathke, slightly altered.) m, Mouth appearing as an elongated slit when relaxed (as in the lamprey); p, perforated pharynx; e, endostyle; g, gonads; 1, liver; at, level of atriopore; intestine; an, anus.

  • ==Reproductive System== The sexes are separate, and the male or female gonads, which are exactly similar in outward appearance, occur as a series of gonadic pouches projecting into the atrial cavity at the base of the myotomes (figs.

  • The gonads are formed in the endoderm (hence " Entocarpeae "), and the generative products are shed into the gastric cavity and pass to the exterior by way of the mouth.

  • On the floor of the stomach are borne the conspicuous gonads (ov), and also tentacle-like processes termed gastric filaments or phacellae, projecting into the cavity of the stomach.

  • The gonads are folds of the endoderm containing generative cells, and are primitively four in number, situated interradially, but each gonad may be divided into two by the partition which separates two adjacent lobes of the stomach, that is to say, by one of the areas of concrescence between exumbral and subumbral endoderm, whence arises a condition with eight gonads which is by no means uncommon.

  • They serve probably for the aeration of the gonads by admitting to their vicinit y water with its dissolved oxygen; they never serve as genital ducts, since the generative products are always dehisced into the stomach and pass out by the mouth.

  • The eight adradial gonads on the subumbral walls of the four radial pouches, representing primitively four horse-shoeshaped gonads each divided into two by an interradial septum.

  • shoe-shaped gonads (ov) mark, Oral arms. ing four stomach-pouches, b t tentacles.

  • The diagnostic features of the class Scyphozoa thus constituted are supposed to be (I) an ectodermal oesophagus or stomodaeum, (2) a gastric cavity subdivided by mesenteries, (3) gonads formed in the endoderm.

  • There remains only the third feature, the endodermal gonads, as an argument for uniting the Scyphomedusae with the Anthozoa, against which must be set all the peculiarities of medusan organization in which the Scyphomedusae resemble the Hydromedusae.

  • ring-canal absent); gonads divided each into two by the septa, hence eight in number; subgenital pits small or absent.

  • Eight gonads.

  • Sessile, stalked, with eight shallow marginal lobes bearing one or more rows of tentacles; without tentaculocysts; with four gonads.

  • The gonads, as in other Arthropoda, are hollow saccular organs, the cavity communicating with the efferent ducts.

  • 4 organs or gonads are borne on the mesenteries, the germinal cells being derived from the inner layer or endoderm.

  • go, Gonads.

  • short, the sulco-lateral and sulculo-lateral pairs are a little longer, but the two transverse are very large and are the only mesenteries which bear gonads.

  • bear gonads.

  • - Radial symmetry has affected neither food-grooves nor thecal plates; nor, probably, nerves, ambulacral vessels, nor gonads.

  • - Radial symmetry affects the food-grooves and, in the more advanced families, the thecal plates; probably also the nerves and ambulacral vessels, but not the gonads.

  • - Pentamerous symmetry affects the foodgrooves and thecal plates; probably also the nerves and ambulacral vessels, but not the gonads.

  • - Radial symmetry affects the food-grooves, and by degrees the thecal plates connected therewith, but not the interradial thecal plates; probably also the nerves and ambulacral vessels, but not the gonads.

  • The gonads are not radiately disposed.

  • Back home in 1977, the Gonads formed their own Scrotum label and released their first single 'Stroke My Beachcomber, Baby'.

  • The gonads begin to function and secondary sexual characteristics begin to appear.

  • The gonads begin to function and secondary sexual characteristics begin to appear.

  • The gonads begin to function and secondary sexual characteristics begin to appear.

  • At around the seventh week of gestation, the gonads (sex organs) begin to change, or differentiate, into the characteristic genitalia of males and females.

  • The gonads begin to function and secondary sexual characteristics begin to appear.

  • In turn, the pituitary releases its own hormones called gonadotrophins that stimulate the gonads and adrenals.

  • It can come from the brain in the form of gonadotrophins or from the gonads and adrenals.

  • If the pituitary output is inadequate, so will be the output from the gonads and adrenals.

  • This should only be done for patients who are not of reproductive age or are not planning to have children, since a large amount can concentrate in the reproductive organs (gonads).

  • Gonads are the organs of sexual differentiation: in the female, they are ovaries; in the male, the testes.

  • The gonads are not independent in their function, however.

  • A number of adverse events can damage the gonads and result in decreased hormone levels.

  • Severe diseases in the liver or kidneys, certain infections, sickle cell anemia, and some cancers also affect gonads.

  • Failure of the pituitary is called hypopituitarism and, of course, leaves the gonads with no stimulation to produce hormones.

  • This results in underdeveloped gonads and often infertility.

  • Chromosomes can be analyzed, and gonads can be, but rarely are, biopsied.

  • Tests may be done that check estrogen levels (women) and testosterone levels (men) as well as FSH levels and LH levels, the pituitary hormones that stimulate the gonads.

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