A HISTOLOGICAL SURVEY OF GONADAL DEVELOPMENT IN ARION ATER L. (MOLLUSCA, PULMONATA)

A method of breeding the slug Arion ater L. in the laboratorywas established. Measurements were made at monthly intervalsof body weight, weight and volume of the hermaphrodite gland,diameter and number of acini, oocytes and other cell types insidethe acini in field and laboratory-reared animals. Male and femalegametes grow simultaneously in the hermaphrodite gland of fieldanimals during the year. High humidity and low temperature causedinhibition of spermatogenesis and increase in the number offemale gametes in laboratory-reared animals. The average rateof increase in diameter of the oocytes of field samples was10 µm per month and in laboratory samples 9 µm permonth. ^*Present address: Department of Biology, School of Sciences,Ferdowsi University, Mashhad, Iran. (Received 30 September 1977;     

THE ANATOMY AND RELATIONSHIPS OF THE ORBITESTELLIDAE (GASTROPODA: HETEROBRANCHIA)

The anatomy of two genera of the marine gastropod family, Orbitestellidae,Orbitestella and Microdiscula, is described. They possess apigmented mantle gland and pallial renal organ, lack a ctenidiumand have a simple hermaphrodite genital system with an externalpenis. They lack buccal cartilages, have a simple oesophagus,a massive jaw and a crystalline style in the stomach. The Orbitestellidaeare shown to be primitive heterobranchs, perhaps related tothe northern-hemisphere freshwater family Valvatidae. (Received 9 September 1989; accepted 30 December 1989)     

DIFFERENTIATION OF SERTOLI CELLS AND POST--REPRODUCTIVE EPITHELIAL CELLS IN THE HERMAPHRODITE GLAND OF ARION ATER(L.) (MOLLUSCA, PULMONATA)

Differentiation of Sertoli cells and post-reproductive epithelialcells during development of the hermaphrodite gland has beendescribed in Arion ater (L.) at the fine structure level. Twodifferent stages of Sertoli cells, active and atrophic, arerecognized. The cytoplasm during the active stage shows highmetabolic activity by many lysosome-like inclusions and otherorganelles. The possible role of steroidogenesis of these cellsis discussed in relation to their fine structure. The post-reproductive epithelial cells appear in the gland approximatelyafter the sheddingof both spermatozoa and oocytes. These cellsmay fill the lumen of the gland and appear syncytial. ^*Present address: Department of Biology, School of Sciences,Mashad University, Mashad, Iran (Received 12 January 1979;     

EFFECT OF A SPERMATOGONIAL CHALONE ON THE GROWING RAT TESTIS

Immature rats were used in an experiment to test the possible influence of a spermatogonial chalone on the expanding spermatogonial population in their developing testes. An extract from adult rat testes was injected intraperitoneally into 33-day-old rats and control animals were injected with an equal amount of saline. Two groups of normal adult rats similarly injected with the testicular extract and saline solutions served as additional controls. Following these injections, all animals were administered a dose of ³H-thymidine 10 hr before sacrifice. An analysis of the labeling indices of the various types of spermatogonia revealed that in young rats injected with testicular extract the percentage of labeled type A spermatogonia was significantly lower than in control animals. In contrast, the labeling indices of Intermediate and type B spermatogonia were similar in the two groups of young rats. In the two groups of adult animals, there was no difference in the labeling indices of type A or of other types of spermatogonia. These data indicated that the saline extract of adult testes contained a substance, a spermatogonial chalone, inhibiting specifically the proliferation of some type A spermatogonia. The results also support the concept that a spermatogonial chalone may intervene, through its action on the spermatogonial stem cell population, to arrest the growth of the seminiferous tubules as the animal reaches maturity.     

The occurrence of C19 steroids in testicular tissue and submaxillary glands of intersex pigs in relation to morphological characteristics.

Five true hermaphrodite pigs and two male pseudohermaphrodite pigs were studied. A 38XX sex chromosome constitution was found in peripheral leucocytes of three true hermaphrodites and in one male pseudohermaphrodite; XX/XY mixoploidy was present in the leucocytes of the remaining male pseudohermaphrodite. The occurrence of C19 steroids, including 16-androstenes, in the testicular tissue and submaxillary gland of intersex pigs was of a similar pattern to that found previously in mature boars, and masculinization of the genital tract was related to the amount of testicular tissue present. It is postulated that in the absence of germ cells in the testicular tissue of intersex pigs the Sertoli cells may be involved in the metabolism of dehydroepiandrosterone to 5-androstenediol, a possible testosterone precursor in the pig. The high levels of 16-androstenes found in the submaxillary gland of intersex pigs indicates that these steroids are responsible for 'boar taint' in these animals. In contrast to the boar, no consistent relationship was found between the occurrence of C19 steroids and the degree of masculinization of the submaxillary gland; it is postulated that the predominantly female genetic constitution may have affected the response of the salivary gland to androgen.     

REPRODUCTIVE SYSTEM AND SPERMATOGENESIS IN THE OPISTHOBRANCH GASTROPOD RETUSA OBTUSA (MONTAGU)

The cephalaspidean opisthobranch Retusa obtusa has an ovotestissimultaneously producing eggs and spermatozoa. Reproductiveorgans are characterized by the hermaphrodite duct and seminalreceptacle together joining the pallial glandular duct whichis differentiated anteriorly to form the ‘albumen’gland, membrane or capsule gland, and mucus gland. The ductof a copulatory bursa joins the common central chamber of thiscomplex. Eggs presumably pass through extended tracts in the3 glands to emerge at a hermaphrodite aperture in the rightside of the mantle cavity. Spermatozoa also emerge at this apertureto a ciliated seminal groove along the right side of the headwhich, in turn, joins copulatory organs folded within the headand opening close behind the right cephalic tentacle: a muscularpenial sac receives 4 elements of prostate gland. Spermatophoreswere never seen. Oocytes, surrounded by several thin folliclecells, reach 150–330 µ, m diameter in larger wintersnails, mostly in the periphery of theovotestis. Spermatocytesand spermatids develop as clusters in association with accessory(Sertoli) cells. The acrosome appears in the centre of a denseanterior plaque, develops as a domed acrosome vesicle on a shortpeduncle and eventually becomes a terminal spike on the nucleustip. The Golgi complex is seen sometimes near the early acrosomebut more often behind the nucleus. Mitochondria aggregate firstahead of the nucleus but then form a mitochondrial derivative,with a glycogen helix, spiralled around the axoneme throughoutthe mid-piece of the tail. This region is marked off from theend-piece of the tail by the annulus. The nucleus becomes long,spiralled with a strong keel, and surrounds the centriolar derivativeat the base of the axoneme.     

Sex-inversion of the hermaphroditic, protogynous teleost Coris julis L. (Labridae)

Sex-inversion of Coris julis , a protogynous hermaphrodite, was studied using histological and cytological criteria. Four stages were recognized: oocyte and oogonial atresia; occurrence of spermatogonia with primordial germ cells (PGC) in the ovarian wall; onset of spermatogonial proliferation; considerable proliferation of spermatogonia and PGC with build-up of seminiferous tubules. Spermatogonia arise from PGC, undifferentiated and bipotential cells, in which mitotic activity was detected.     

Photoperiod and Fertility in Rottboellia exaltata L.f.

In the short-day grass Rottboellia exaltata L.f., one of theflowers of the sessile spikelet at each node of the inflorescenceis morphologically male and the other hermaphrodite. When plantsare exposed to 12 weeks of long days before induction to flowerin short days, the male flower is sterile, and self-pollinationoccurs in the hermaphrodite flower before exsertion of the anthers.With 17 weeks of long days before exposure to short days, themale flower becomes fertile in the first-formed inflorescences,and some of the hermaphrodite flowers are probably open to cross-pollination.     

Ultrastructural study of sex inversion in a protogynous hermaphrodite, Epinephelus microdon (Teleostei, Serranidae).

Sex inversion of Epinephelus microdon, a protogynous hermaphrodite was studied using light and electron microscopic criteria. The sex changes takes place within ex-ovarian lamellae in which, in addition to spermatogonia, numerous primordial germ cells (PGCs) were detected. These undifferentiated and bipotential early germ cells are involved, as well as spermatogonia, in the building up of the testis.     

A COMPARISON OF THE LIFE CYCLES OF THE SLUGS DEROCERAS RETICULATUM (MULLER) AND ARION INTERMEDIUS NORMAND ON PERMANENT PASTURE

Life cycles of the slugs Deroceras reticulatum and Arion intermediuswere compared over a four-year period on permanent pasture nearOvingham, Northumberland. Both species were semelparous, theirlife cycles taking about one year. D. reticulatum, unlike A.intermedius and other species, had two overlapping generationsthat laid their eggs in late spring and autumn respectivelyand also had one instead of two immature phases in its lifecycle. The pattern and rates of growth for the immature phasesin the life cycle of A. intermedius differed markedly from thosedescribed under laboratory conditions. Growth in the infantilephase was delayed in the field by low winter temperatures whilesecond stage growth was usually delayed in late spring by dryconditions. The life cycle of A. intermedius appears to be synchronisedby seasonal changes in photoperiod, unlike that of D. reticulatum.Growth in D. reticulatum continued throughout the winter monthsexcept under exceptionally cold conditions and was not usuallydelayed by dry conditions in spring. The size of hermaphroditegland relative to body weight in D. reticulatum reached a maximumin mature-unmated slugs and then became progressively smalleras the slug approached the post-reproductive stage which wasrelatively brief. Exceptionally dry conditions in 1962 delayedthe development of the hermaphrodite gland, the maximum sizereached was significantly reduced and fewer eggs were laid. (Received 17 September 1987; accepted 2 January 1988)     

Fine structural studies of rat seminal vesicle in castrated and intact animals following estrogen treatment.

The effect of estradiol and/or testosterone upon secretion by seminal vesicle in castrated and intact rats was assessed in young adult Sprague-Dawley rats, using light microscopy (LM), transmission (TEM) and scanning (SEM)electron microscopy. Hormones were injected daily for ten days beginning ten days after castrations were performed. The normal rat seminal vesicle, as revealed by SEM, was characterized by a large saccular lumen with highly folded walls. Cell surfaces were covered with microvilli, or occasionally displayed a protruding, ruffled surface, sparsely covered with short microvilli. Cytology was normal in testosterone-treated animals. Estradiol treatment of castrated animals stimulated secretion by seminal vesicle epithelial cells as evidenced by the presence of normal secretory bodies, the presence of RER, and moderately hypertrophied Golgi complexes. These glands were not heavier than were glands from castrated, untreated animals, although the epithelial cells were significantly taller. Secretion was maintained in intact animals treated with estradiol, although glands were smaller and epithelial height was reduced. Estradiol and testosterone treatment in combination did not appear to have an additive effect on secretion, weight of the gland, or epithelial height. The following results support the hypothesis that estrogen-induced prolactin synthesis and release may be involved in the mechanism by which estradiol effected stimulation of seminal vesicle epithelium. Prolactin-treated, castrated animals exhibited focal areas of stimulated epithelium. In hypophysectomized animals (untreated controls), the seminal vesicle epithelium retained some secretory bodies and secretory fluid in the glandular lumen; epithelial height was taller than that in castrated controls. Estrogen treatment reduced the epithelial height to that of castrated controls; there was no evidence of secretion. This suggests that in the absence of anterior pituitary hormones, including prolactin, the stimulatory effect of estradiol on seminal vesicle epithelium was nullified. In adrenalectomized/castrated animals, estradiol treatment stimulated secretion in seminal vesicle epithelium just as in non-adrenalectomized/castrated animals. This indicates that the adrenal gland plays a non-essential role in the action of estrogen on seminal vesicle epithelium.     

An overview of cell renewal in the testis throughout the reproductive cycle of a seasonal breeding teleost, the gilthead seabream (Sparus aurata L)

The gilthead seabream is a protandrous hermaphrodite seasonal breeding teleost with a bisexual gonad that offers an interesting model for studying the testicular regression process that occurs in both seasonal testicular involution and sex change. Insofar as fish reproduction is concerned, little is known about cell renewal and elimination during the reproductive cycle of seasonal breeding teleosts with asynchronous spermatogenesis. We have previously described how acidophilic granulocytes infiltrate the testis during postspawning where, surprisingly, they produce interleukin-1beta, a known growth factor for mammalian spermatogonia, rather than being directly involved in the elimination of degenerative germ cells. In this study, we are able to discriminate between spermatogonia stem cells and primary spermatogonia according to their nuclear and cytoplasmic diameters and location in the germinal epithelium, finding that these two cell types, together with Sertoli cells, proliferate throughout the reproductive cycle with a rate that depends on the reproductive stage. Thus, during spermatogenesis the spermatogonia stem cells, the Sertoli cells, and the developing germ cells (primary spermatogonia, A and B spermatogonia, and spermatocytes) in the germinal compartment, and cells with fibroblast-shaped nuclei in the interstitial tissue proliferate. However, during spawning, the testis shows few proliferating cells. During postspawning, the resumption of proliferation, the occurrence of apoptotic spermatogonia, and the phagocytosis of nonshed spermatozoa by Sertoli cells lead to a reorganization of both the germinal compartment and the interstitial tissue. Finally, the proliferation of spermatogonia increases during resting when, unexpectedly, both oogonia and oocytes also proliferate. This proliferative pattern was correlated with the gonadosomatic index, testicular morphology, and testicular and gonad areas, suggesting that complex mechanisms operate in the regulation of gonocyte proliferation in hermaphrodite fish.     

Hormone Interaction in Apical Dominance in Phaseolus vulgaris L.

Gibberellic acid (GA₃), kinetin, and indole-3yl-acetic acid(IAA) were applied to roots of Phaseolus vulgaris under twodifferent light intensities and when either young or old leaveswere removed In all cases GA₃, promoted stem and lateral growth,especially when light intensity was reduced. Promotion by GA₃,of stem growth under reduced light was reduced if IAA and kinetinwere present; promotion of lateral growth under reduced lightwas reduced if IAA was added and eliminated if kinetin or kinetinplus IAA were added to GA₃. Removal of young and mature leavesreduced main stem growth; removal of young leaves promoted,and of mature leaves reduced, lateral shoot growth. We suggestthat shoot growth and apical dominance are governed by the balanceof hormones present in elongating internodes. There may be twoways of modifying this balance; firstly by altering light, temperature,or nutrients, or by applying hormones generally to the plant.Secondly, local modifications can be made by removing apicesor young leaves, or applying hormones in lanolin to specificareas. Knowledge of both the general and local conditions maybe necessary for a complete understanding of apical dominance.     

Gland Cells in Resin Canal Epithelia in Guayule (Parthenium argentatum) in Relation to Resin and Rubber Production

Schizogenous resin canals develop in the pith and cortex ofthe primary stem tissue in guayule (Parthenium argentatum Gray).In secondary tissue concentric rings of resin canals are producedfrom derivatives of the vascular cambium. Both resin and rubberaccumulate in the epithelial cells of the canals. These havethe characteristics of gland cells. Resin is secreted into thecanals and rubber accumulates in the surrounding parenchymacells as well as the gland cells, especially in winter. Younggland cells contain modified plastids and smooth tubular endoplasmicreticulum. These organelles probably accommodate the compartmentalizedsteps of the isoprenoid biosynthetic pathway leading to theproduction of isopentenyl pyrophosphate. As these ultrastructuralcharacteristics only exist in young gland cells of the currentseason's growth they seem to be the sole source of the precursorsfor both resin and rubber formation. Parthenium argentatum, guayule, resin canals, gland cells, plastids, smooth endoplasmic reticulum, rubber, resin, epithelial cells, ultrastructure     

The annual involution and regeneration of the thymus in hibernating animals and perspectives of its studies in gerontology and stem cell proliferation

Data on a unique phenomenon of annual involution and neogenesis of thymus gland in hibernating animals are reviewed. In accordance with morphological findings, the annual thymus involution in hibernating animals is close to the age-dependent thymus involution occurring in all mammals once in a lifetime. In opposite, thymus involution in hibernating animals is totally different from the accidental involution. During hibernation, the thymus tissue is substituted by the brown fat tissue. In the spring, thymus gland neogenesis stats with intensive growth of epithelial tissue followed by lymphocyte infiltration and exhaustion of brown tissue. Morphological changes in the thymus gland within the annual cycle were compared with seasonal dynamics of structural and functional changes in peripheral lymphoid organs (spleen, lymphoglandular, peritoneal fluid). A general regularity was observed involving a decreased functional activity of immune cells in autumn, its sharp depression during winter hibernation, and obvious increase in summer with the onset of a season of animal activity. It is supposed that a sharp increase in the tumor necrosis factor (TNF) production observed during short-term awakenings in winter may serve an important link in this unique immune adaptation mechanism. The season changes in cellular TNF secretion suggest a mobilization of protective resources in hibernating animals in autumn and winter, i.e. in seasons when the thymus gland activity is depressed. The annual involution of thymus gland cannot be related to droppings in the environmental or body temperatures, as it comes long before their fall. Additionally, it is not related to ageing, as it occurs already in young hibernating animals. The role of hormones, including melatonine and corticosteroids, in mechanisms regulating thymus gland involution in hibernating animals is discussed.     

REPRODUCTIVE BIOLOGY OF THE SESSILE GASTROPOD VERMICULARIA SPIRATA (CERITHIOIDEA: TURRITELLIDAE)

The reproductive and developmental biology of the sessile gastropodVermicularia spirata (Philippi, 1836), collected from the FloridaKeys, was studied from living and preserved material. Individualsof this species attach themselves to a variety of substrata,but were mainly found embedded in the white sponge Geodia gibberosa.Pallial reproductive structures of both sexes of V. spiratawere found greatly to resemble those of Turritella communis,a free-living member of the same family. In both species, animalsof both sexes have open pallial ducts formed by two wide, recurvedlaminae. In the female of V. spirata, the laminae of the pallialoviduct serve as a capsule gland; a pair of side pockets representa fertilization pouch (possibly doubling as a copulatory bursa)and a seminal receptacle. The functional significance of theextensive, open, pallial sperm duct is not yet clear. Vermiculariaspirata is a protandrous hermaphrodite, and small males arefree-living; they become attached at about the time they undergosex reversal. Fertilization is probably brought about by malescrawling close to the apertures of the large, sessile femalesbefore releasing sperm. Egg capsules are brooded in the females'mantle cavities. Ova of about 300 µm diameter give riseto large (about 600 µm long) swimming-crawling veligerlarvae with shells of two and a half whorls. The veligers arecapable of metamorphosis at the time of hatching, but siblingsfrom one brood metamorphosed over a two-week period in the laboratory.Juvenile snails grew rapidly by filtering phytoplankton addedto their culture water. The life history of V. spirata is welladapted to assure fertilization and recruitment in a speciesotherwise committed to a sessile, filter-feeding existence. (Received 3 February 1989; accepted 19 April 1989)     

Recombinant human insulin-like growth factor I stimulates all stages of 11-ketotestosterone-induced spermatogenesis in the Japanese eel, Anguilla japonica, in vitro.

In this study, we examined the in vitro effects of insulin-like growth factor I (IGF-I) in the presence or absence of 11-ketotestosterone (11-KT: the spermatogenesis-inducing hormone) on the proliferation of Japanese eel (Anguilla japonica) testicular germ cells. Initially, a short-term culture (15 days) of testicular tissue with only type A and early type B spermatogonia (preproliferated spermatogonia) was carried out in Leibovitz-15 growth medium supplemented with different concentrations of recombinant human IGF (rhIGF)-I or -II in the presence or absence of 10 ng/ml of 11-KT. Late type B spermatogonia (proliferated spermatogonia) were observed in treatments of 100 ng/ml of both rhIGF-I and -II in combination with 11-KT, indicating the onset and progression of spermatogenesis. In all tested rhIGF-I concentrations (except 0.1 ng/ml) supplemented with 11-KT, late type B spermatogonia were detected in at least one individual. Then, we proceeded with an in vitro 45-day culture of testicular tissue with 100 ng/ml of rhIGF-I in the presence or absence of 10 ng/ml of 11-KT to test the long-term effects of rhIGF-I on the spermatogenetic cycle. The presence of all types of germ cells, including spermatozoa, in the testis cultured with the admixture of the two hormones indicated that the germ cells underwent complete spermatogenesis whereas no germ cell proliferation was observed when the rhIGF-I was applied alone. These results suggest that IGF-I in the presence of 11-KT plays an essential role in the onset, progress, and regulation of spermatogenesis in the testis of the Japanese eel.     

Gynodioecy in Cirsium chikushiense Koidz. (Compositae)

A study of the morphology and function of flowers in Cirsiumchikushiense revealed that the species was distinctly gynodioecious.Self-incompatible hermaphrodite florets produced both seedsand pollen grains, while female ones produced seeds but no pollengrains at all. The degenerated stamens of females were not onlysmaller but also sometimes occurred at a lower position insidethe floral tube than in hermaphrodites. The stigmata of femalesoften developed more fully than those of hermaphrodites. Thefrequencies of female plants in natural populations varied from15·5 to 50%. Almost all the pollinators stayed on bothfemale and hermaphrodite heads only to collect nectar. The femaleplants of this species may be more specialized in their genderby saving the cost of not only pollen grains but also stamens,and may be maintained by sufficient pollinators in natural populations.This gynodioecy may provide an example of nuclear-cytoplasmicmale sterility.Copyright 1994, 1999 Academic Press Sex expression, gynodioecy, Cirsium chikushiense, Compositae, male sterility, degenerated stamen, female frequency     

Gene discovery in Carcinus maenas and Homarus americanus via expressed sequence tags

Expressed sequence tags (ESTs) were produced for normalizedcDNA libraries prepared from several tissues of 2 marine crustaceans,the green shore crab Carcinus maenas and the American lobsterHomarus americanus. Tissues represented in the Carcinus librarywere anterior and posterior gills, hypodermis, heart, hepatopancreas,antennal gland, brain, testis, and skeletal muscle, obtainedfrom animals acclimated to 35 and 10     

The effects of sialoadenectomy and exogenous EGF on taste bud morphology and maintenance

Taste buds on the dorsal tongue surface are continually bathedin saliva rich in epidermal growth factor (EGF). In the followingexperiment, taste bud number and morphology were monitored followingsubmandibular and sublingual salivary gland removal (sialoadenectomy),to determine if EGF plays a role in the maintenance and formationof taste buds. Adult male rats were divided into four groups:sialoadenectomized (SX, n = 4); sialoadenectomized with EGFreplacement (SX + EGF, n = 5); sham-operated (SH, n = 4); andsham-operated with exogenous EGF (SH + EGF, n = 5). After a3 week recovery, SX + EGF and SH + EGF animals were given 50µg/day EGF in their drinking water for 14 days. At day14, saliva was collected, the animals were killed and the presenceof EGF determined by radioligand-binding assay. Tongues wereremoved and histologically examined for the presence and morphologyof taste buds on fungiform and circumvallate papillae, or immunostainedfor the presence of EGF, TGF