Gonad Volume Research Articles

Anti-müllerian hormone and freemartinism: inhibition of germ cell development and induction of seminiferous cord-like structures in rat fetal ovaries exposed in vitro to purified bovine AMH.

In 13 and 14-day old fetal rat ovaries maintained 3 to 10 days in organ culture, purified bovine anti-Müllerian hormone (AMH) (1.5 to 3 micrograms/ml) induced a characteristic freemartin effect. Gonadal volume and germ cell number were significantly reduced, compared to control ovaries cultured in anhormonal medium, and epithelial cells with large clear cytoplasm linked by interdigitations differentiated in the gonadal blastema. These cells resembling rat fetal Sertoli cells became polarized and formed seminiferous cord-like structures delineated by a basal membrane containing laminin and fibronectin as is the case of testicular seminiferous cords at the first step of their differentiation. These data indicate that AMH is probably the testicular factor responsible for the morphological modifications of bovine freemartin gonads and suggest that this hormone could also be involved in normal morphological differentiation of the testis. In contrast, in fetal rat ovaries, AMH did not trigger the testosterone production which occurs in freemartin gonads at an early stage of the gestation.

Purified bovine AMH induces a characteristic freemartin effect in fetal rat prospective ovaries exposed to it in vitro.

To determine whether anti-Müllerian hormone (AMH) is responsible for the gonadal lesions observed in bovine genetic females united by placental anastomoses to male twins (freemartins), prospective ovaries of fetal rats were exposed to purified bovine AMH in vitro. In cultures initiated at 14 days p.c. and maintained 3 to 10 days, AMH consistently induced a characteristic 'freemartin effect', namely reduction of gonadal volume, germ cell depletion and differentiation, in the gonadal blastema, of epithelial cells with large clear cytoplasm linked by interdigitations, resembling rat fetal Sertoli cells. These cells tend to become polarized and form cords, delineated by a continuous basal membrane containing laminin and fibronectin. Such structures, resembling developing seminiferous cords, were not detected in control ovarian cultures. These data strongly suggest that AMH is the testicular factor responsible for triggering the morphological abnormalities of freemartin gonads.

Gonadal development of the chick embryo following microsurgically caused agenesis of the mesonephros and using interspecific quail—chick chimaeras

Mesonephric agenesis was achieved by microsurgical excision of the left Wolffian duct and the underlying intermediate mesoderm of different regions between somites 16 and 23 in chickens after 50-52 h of incubation (stage 14 HH). Quail-chick chimaeras were produced by transplantation of corresponding quail tissue in the region of somites 18-21. A morphometrical analysis of the mesonephric and gonadal area in cross sections shows that the intermediate mesoderm from somites 16 to 23 develops into the mesonephros. A partial agenesis of the mesonephros brought about by removal of the intermediate mesoderm at the level of somites 18 to 21 at stage 14 leads to a mean reduction of the gonadal volume of 37.8% compared to the volume of the untreated side at stage 30. Transplantation of quail intermediate mesoderm in this region of the excision results in development of a hybrid mesonephros. Consequently, the gonads are invaded and colonized by quail cells mobilized from mesonephric corpuscles examined at stage 30, 35 and 36. These results are discussed in terms of the origin of the gonadal stroma during this developmental period; they show that in the region from the third to the sixth segment the ventromedial part of the differentiating mesonephros participates in the contribution of stromal cells to the gonad.

The interaction between diet and density in influencing reproductive output in the echinoid Evechinuschloroticus (Val.)

The effects of diet, density, and sex on the reproductive output and survival of Evechinus chloroticus (Val.) have been investigated by means of a field experiment. Densities used ranged between 2 and 20 per 0.5-m 2 cage. The urchins were given single species diets of Ecklonia radiata (C.Ag.) J.Ag., Carpophyllum maschalocarpum (Turn.) Grev., C. angustifolium J.Ag., and coralline algae. Diet and density interacted in influencing both the size of gonads and their histological condition. At low density those individuals fed Ecklonia had significantly larger gonads than did those fed less preferred algae. This effect disappeared at higher density and was contrasted with the relative constancy in size of gonad with increasing density for those animals fed other diets. Gonad volume was a useful predictor of reproductive output. In both winter and spring the size of gonad closely reflected differences in the representation of gametocytes within the gonad. The sex of individuals did not significantly affect the size of gonad; the low power of tests for this effect were, however, noted. The results presented are similar to those given in other studies of this nature. Difficulties in extrapolating these results to natural situations have been discussed and it is argued that knowledge that individual Evechinus display preferences among species of algae is of little use in predicting the field diet of this species.

Fine structure of Lasaea subviridis and Mysella tumida sperm (Bivalvia, Galeommatacea)

Lasaea subviridis and Mysella tumida sperm resemble the primitive spermatozoan type, but exhibit several unique morphological features. L. subviridis sperm heads vary in shape and size owing to differing degrees of nuclear condensation. A fully mature, heterogenous acrosomal vesicle with an associated axial rod is present. Up to 50% of L. subviridis sperm in developing gonads have conspicuously angled flagella that propel the sperm cells in irregular helical paths. This may represent a penultimate stage in sperm development because the remainder of the sperm cells have posteriorly-directed flagella and swim in a nonhelical anterior direction. A trend toward a reduction in both nuclear condensation and swimming ability may be a long-term consequence of increasing degrees of localized, but non-internal self-fertilization in marine invertebrates that brood. Mysella tumida sperm are monomorphic and possess numerous microvilli (30–60 nm in diameter and up to 5.7 μm in length) that resemble stereocilia and radiate from the cell membrane surrounding the basal body. In this species, the sperm cell does not have an axial rod, and the complex acrosomal vesicle contains five distinct zones of varying electron opacity. One of these zones is a transverse, electron-opaque band that is apparently composed of rolled-up membrane. Following acrosomal breakdown, this membrane unfolds to cover the anterior tip of the sperm cell. Although both L. subviridis and M. tumida are hermaphroditic, the relative size of their male investments is conspicuously different. Approximately 40–50% of the M. tumida gonadal volume is testis compared with about 5% of that in L. subviridis.

SOME QUANTITATIVE ASPECTS OF REPRODUCTION AND GROWTH OF THE RED ABALONE, Haliotis rufescens SWAINSON

ABSTRACTReproduction and growth of a laboratory‐held population of red abalone, Haliotis rufescens, collected at Mendocino, California, were studied at the Telonicher Marine Laboratory, Trinidad, California. Specimens were continuously supplied with and consumed bull kelp fronds, Nereocystis luetkeana. Following induction of artificial spawning, specimens were sacrificed at 15‐day intervals to histologically describe and record the timing of gonadal phases, and to measure gonadal growth. A modified Gonad Bulk Index (GBItc) detected temporal changes in gonad volume and was highly correlated with defined stages of ovarian development. For specimens sexually mature when collected, viable gametes were spawned again 75 to 90 days following artificial spawning. Some specimens were spawned 3 times during a one‐year period. The laboratory regime increased somatic growth and fecundity, and reduced the minimum size at spawning relative to equivalent sized specimens from the field. Estimated fecundities for laboratory‐conditioned specimens averaged 260% greater than for field‐conditioned specimens. The minimum size at spawning for laboratory‐conditioned specimens was less than that for field‐conditioned specimens. The ratio of spawners to non‐spawners for specimens less than 100 mm long was significantly higher for laboratory‐conditioned specimens. Laboratory‐conditioned specimens less than 100 mm long had fecundities comparable to field‐conditioned specimens up to 140 mm long. The criterion of gonadal phases developed for laboratory specimens was compared to a field population from the collection area and indicated an annual gametogenic cycle. About 120 days are required for the completion of a reproductive cycle for red abalone in the field. Natural spawning occurred from April through July, with a peak in May. There was no evidence of partial spawning.

Thyroid and annual gonad development, body weight, plumage pigmentation, and bill color cycles of lal munia, Estrilda amandava

Long-term administration of l-thyroxine (T 4) in the wax bill (lal munia) inhibited the current gonad development cycle, and the increase in gonadal volume in the second cycle was suppressed only by higher concentrations. Gonadal inhibition by high but not by low doses of l-T 4 was associated with a failure in the development of LH-dependent pigmented nuptial plumage. This suggests that l-T 4 depresses FSH secretion more readily than LH secretion. The results indicate that the effects of l-T 4 administration on the body weight cycle depends upon the physiological and/or gonadal status of the bird at the start of the experiment and that the juvenile hhpothalamo-hypophysial-gonadal axis is more sensitive to l-T 4 than that of the adult birds. The bill color, like plumage pigmentation, appears to be LH controlled. It is suggested that while thyroid hormone, acting by way of the hypothalamo-hypophysial complex and/or by direct action on the feather papillae, modulates the annual cycles of plumage pigmentation, bill color, gonad development, and body weight of lal munia, the finch has an endogenous mechanism which enables it to adapt to chronic hyperthyroidism in such a way that breeding occurs at the normal time of the year.

Reproductive periodicity inEvechinus chloroticusin the Hauraki Gulf

Abstract Test diameter and gonad volume were recorded over 1 year for bimonthly samples of Evechinus chloroticus (Valenciennes) from each of 3 subtidal populations 10 km apart in the Hauraki Gulf. Histological analysis was used to relate cellular events during gametogenesis to the annual cycle of change in gonad size. Mean gonad sizes of the different sea urchin populations were compared by analysis of covariance. Gametogenesis began in the spring, and major spawning occurred in mid to late summer. The proportion of the gonads taken up by nutritive phagocyte cells increased from autumn to spring. During proliferation and growth of gametes the nutritive phagocytes declined in abundance and globulation, suggesting that reserves stored in these cells were transferred to developing gametes. Gonad size doubled during gametogenesis, declined after spawning, and remained low in autumn and winter. Differences in gonad size between populations were significant during most of the year, and were most pronounced in m...

Reproductive ecology of the intertidal sea anemones Anthopleura xanthogrammica (Brandt) and A. elegantissima (Brandt): Body size, habitat, and sexual reproduction

Anthopleura xanthogrammica (Brandt) and A. elegantissima (Brandt) were collected monthly (1974–1976) from a variety of intertidal habitats in Washington State. Histological preparations were used to examine oocyte maturation, testis maturation, gonad number, and gonad volume. Maturation was examined over two years and both species were found to build gonad during the winter, spring, and summer followed by spawning in the late summer and autumn. Gonad volume and gonad number increase with individual size after a certain minimum size has been reached. Gonad volume as a function of body size does not change with habitat although the size structure of the population may change substantially.

Impact of different dietary protein contents on fecundity and fertility in the female guppy, Poecilia reticulata (Peters).

Individual fecundity and reproductive output (number of ova plus vitellogenic oocytes) were significantly higher in groups of guppies (Poecilia reticulata, Peters) given 72% protein compared with females fed on either 53%, 23%, or 15% protein. Ovum diameter and size of vitellogenic oocytes were significantly larger in females exposed to either 72% or 53% protein than in groups fed on 15% protein. Females living on a 72% protein-rich diet showed a significantly higher total body weight, ovarian length, width, height, gonad volume and weight than groups fed on either 23% or 15% protein. Significantly higher values of these variables were also found among females given 53% protein compared with groups fed on 15% protein. Average gonadosomatic index increased with higher protein amounts. Growth was significantly higher in females ingesting 72% protein than in groups fed on either 42% or 23% protein.

Movement, morphology, reproductive periodicity, and some factors affecting gonad production in the seastar Astrostole scabra (Hutton)

At Kaikoura, New Zealand (42°25′S: 173°42′E), tagged, immature Astrostole scabra (Hutton) usually remained within intertidal pools for <30 days. There was no seasonal vertical migration or intermixing of sub-populations. Intertidal seastars were smaller, had a thicker skeleton, and were damaged more frequently than their subtidal counterparts. The onset of sexual maturity in this species occurred coincidentally with the adoption of an exclusively subtidal habitat (20–146 m), the attainment of a radius of at least 110 mm, and a reduction in skeleton thickness. In 1975, 1976, and 1977, spawning was in late August-early September. Gametogenesis commenced in February–March. There was no seasonal inverse correlation between gonad and pyloric caeca indices. In undamaged, subtidal seastars of both sexes, gonad production was related to body size such that the volume of gonad produced by August increased linearly with respect to eviscerated wet weight. Regeneration partly suppressed gonad production, and large intertidal seastars had reduced gonad indices. The periodicity of reproductive events could not be correlated unequivocally with any physical or biotic exogenous environmental factor.

Development of Trichobilharzia ocellata in Lymnaea stagnalis and the effects of infection on the reproductive system of the host.

Juvenile specimens of Lymnaea stagnalis were exposed to 0 or 4 miracidia of Trichobilharzia ocellata. Highly productive infections developed in all infected snails. Qualitative and/or quantitative light microscopic observations were performed at various intervals between day 0 and 83 post exposure (p.e.). Gonadal maturation started between day 4 and 7 p.e. in all snails, but in infected animals gonadal growth was retarded considerably after day 7 and was blocked from day 19 onwards. This resulted in very small gonads (10% of the volumes of those of controls on day 83 p.e.) in infected snails, in which however, gametogenesis was initially normal. Due to the small gonad volume gamete production was highly reduced. From day 33 onwards spermatogenesis appeared to be inhibited and around day 83 oocyte maturation seemed to be impaired. The accessory sex organs (ASO) of infected snails showed a similar reduced growth. The cellular differentiation and production of secretory granules in these small ASO was normal albeit delayed in both the male and female organs. The severe reduction in growth of the gonad and the ASO started in the presence of immature primary sporocysts, the later effects on gametogenesis were simultaneous with the production of massive numbers of cercariae. These results are discussed in view of the available data on the endocrine control or reproduction in L. stagnalis. It is suggested that either the secretion of gonadotrophic hormones or the response of their targets is reduced by humoral effects of the parasites.

The effects of population density on fecundity and fertility in the guppy, Poecilia reticulata (Peters)

Experiments were performed to examine the influence of population density on the fecundity and fertility in the guppy, Poecilia reticulata. The frequency of females with only ova or with different combinations of reproductive units and developmental stages in the ovary was significantly different between different densities but not between females with one and two gestations from the same population density. The ovarian width of females with one gestation from the lowest density was significantly larger than in the highest population density. Gonad length and height and ovarian volume of females with two gestation periods were larger in the lowest compared with the highest density. After one gestation, females at the lowest population level had greater ovarian length, height, gonad weight, width and volume compared with those from the higher density. Ovarian length, height and volume and gonad weight were also significantly greater among females of two gestation periods in the lowest than in the second lowest density. The average gonadosomatic ratio was highest in the lowest population density. A significant correlation was found between gonad volume and total body weight and between gonad volume and ovarian weight of females at every population level. This was also the case when ovarian weight vs. total body weight was examined in each population density. Only at the lowest population level was there a significant correlation between fecundity and total body length and between fertility and body length. A significant relationship was also found between gonad volume and total body length and between gonad weight and body length at the same population level. No significant difference of fecundity and ovum size was found between females of one and two gestation periods from the same density. Fecundity and fertility were significantly higher among females of one and two gestation periods from the lowest than from the highest density.

Factors controlling variation in the seasonal spawning pattern of Lytechinus variegatus

A population of the regular sea urchin Lytechinus variegatus was sampled, and the gonad volume and test diameter recorded at monthly intervals for 10 years. Parameters abstracted from the data included the size and date when the gonads were full and when they were spent, the spawning pattern, and the spawn output. Environmental parameters available were sea temperature and rainfall. Correlations were determined among these. A correlation was also found between the appearance in successive years of a brood of young urchins on the shore and the temperature and rainfall.

The breeding cycles of a sand dollar and a sea urchin

1.1. The breeding cycle of the sand dollar, Echinarachnius parma, was determined by computing the montly gonad index, and compared to the breeding cycle of the sea urchin Strongylocentrotus droebachiensis.2.2. The sand dollar had its highest gonad index in August and the sea urchin had its highest index in February.3.3. The sand dollar spawned during November and December whereas the urchin spawned during March–May.4.4. The gonad indices of males and females followed a similar time pattern in the sand dollar, but the males had a smaller gonad volume than females during the summer months.

Quantitative characteristics of oocytes in the ovaries of white rats suffering from acute radiation sickness

A study was made of the content of persistent and atresic primordial growing and cavitary follicles in the ovaries of sexually mature and immature albino rats after general X-irradiation in a dose of 600 r. During the first days after the irradiation the main mass of the oocytes was seen to perish. The drop of the number of primordial follicles was more pronounced. No restoration of the sex cells occurred in the irradiated rats, However, up to 6 months after the action of ionizing radiation some primordial growing and cavitary follicles had a normal structure. The ovaries of immature rats were more radiosensitive. It has also been established that changes in the gonad volume did not reflect the dynamics of the sex cell content at various periods of acute radiation sickness.

ANNUAL REPRODUCTIVE CYCLES OF THE CHITONS, KATHERINA TUNICATA AND MOPALIA HINDSII

1. The reproductive cycles of two species of chitons, Katherina tunicata and Mopalia hindsii, collected in Monterey Bay are recorded, the first for three years and the second for two.2. Katherina breeds in the summer, Mopalia in the fall and winter.3. In each case the gonad index (ratio of gonad volume to body weight times 100) rises gradually and falls rather precipitously as spawning occurs. Differences in onset of breeding occurred during the years for which records are available, suggesting timing of events by local conditions.4. Blood protein, non-protein nitrogen, and reducing sugar vary during the year but it is not clear whether these variations are significantly correlated with reproductive condition.

THE ANNUAL REPRODUCTIVE AND NUTRITIONAL CYCLES IN TWO WESTERN SEA URCHINS

1. The degree of gonadal development in the purple sea urchin, Strongylocentrotus purpuratus, was measured by taking the gonad index, or ratio of volume of gonad to wet weight of urchin, every two weeks for a year (1953-54) in samples of 20 urchins obtained from each of two localities, Pescadero Point on the Monterey Peninsula, and Yankee Point, 10 miles south.2. For S. purpuratus from both places, the average gonad index rose during the fall to a peak twice as high as that reached the previous year, and this peak was maintained at a fairly constant level from January through May.3. Climatic factors, rather than ecological, are therefore thought to have the greater effect upon gonad growth. A clear-cut correlation was not established for any factor, but ocean temperature is known to have been higher during the winter of 1953-54 than in the previous year.4. Determination of the gonad index for monthly samples of 10 specimens of the large western sea urchin, S. franciscanus, taken from below the tide pools of the Hopkins Marine Station, indicated a single reproductive cycle, but a much shorter breeding season, the peak of which was reached later than that of S. purpuratus.5. Though males were found to have fertile gametes for a greater part of the year than females, no significant difference was found in the reproductive cycles of male and female urchins in either species, as measured by gonad index.6. The great growth of gonads was not correlated with an increase in NPN (non-protein nitrogen) or RS (reducing sugar) in the body fluid of either species. However, greater mobilization, i.e., transport from gut to gonad, could not be determined by the methods used.7. No seasonal variation of RS was found in either species. NPN was also invariant in S. purpuratus, but showed a marked increase in S. franciscanus during the summer.8. In both species there was a much greater variability of RS than of NPN, suggesting no regulation of RS, but a degree of regulation of NPN. RS was skewly distributed, while NPN was normally distributed in nearly all samples, a fact which may be partially explained by the feeding habits of the animals.9. Very small quantities of protein nitrogen of the order of 0.5 mg. per cent were found in the filtered body fluids of a few specimens of each species.

A Comparison of the Biology ofEchinus esculentusin different Habitats. Part III.

1. Gonad examinations were made on monthly samples ofEchinus esculentusfrom Plymouth in 1934, 1935, and 1936.2. Spawning is from February–March to May, 50% spawning occurring at a temperature of 9.2–9–7° C. compared with 7.0—7.8° C. in the Isle of Man. There was a winter drop in gonad volume one year, but not the other.3. The nature, distribution and source of the pigments in the shell are discussed, and it is shown that pigment is found in quantity in the intestine only in the summer and autumn.4. The known facts with regard to the seasons of growth, spawning, etc., are brought together into a generalized diagram.