Secondary Testes Research Articles

Localisations tumorales secondaires testiculaires

Testis tumors are uncommon in oncology, and testicular metastasis from distant solid tumors are even rarer. We present two cases encountered in our department of pathology in CHU de Rennes, France. Moreover, we collected all reported cases in the Medline/PubMed databases of non-hematopoietic secondary testis tumors in adults, excluding autopsy studies, to propose an integrative study on this topic. In total, we report 98 cases of secondary testis lesions to prostate (n=38, 38.77%), colorectal (n=19, 19.39%), gastric (n=12, 12.24%), kidney (n=7, 7.14%), lung (n=6, 6.12%) and other primary cancers. The median age at diagnosis was 66.5 years. We identified significantly more prostate adenocarcinoma (P<0.0001) when the primary tumor was known and significantly more colorectal adenocarcinoma (P=0.035) and pancreatic adenocarcinoma (P=0.002) when the primary tumor was unknown. The age at diagnosis was older when the primary tumor was known (P=0.007). We present the challenges for the diagnosis and propose some elements for diagnosis orientation. Finally, we discuss the possible ways of metastatic dissemination from primary site to testis, as illustrated by the two cases we present.

Late toxicities and recurrences in patients with clinical stage I nonseminomatous germ cell tumor after one cycle of adjuvant BEP versus primary retroperitoneal lymph node dissection: A 13-years follow-up analysis of a phase III trial cohort.

5512 Background: One cycle of adjuvant BEP has shown superiority in recurrence free survival over RPLND in patients (pts) with clinical stage (CS) I nonseminomatous germ cell tumor of the testis (NSGCT) (JCO 2008). We report recurrences and late toxicities of this randomized trial after 13 yrs of follow-up (FU). Methods: Questionnaires of 382 unselected pts with CS I NSGCT treated within a phase III trial comparing recurrence rate after 1 cycle of adjuvant BEP (arm A) vs. RPLND (arm B) were evaluated regarding recurrences and late toxicity. Overall (OS) and progression free survival (PFS) was calculated by Kaplan-Meier and arms were compared using logrank test. Categorial data were analyzed by chi-square test (PRISM v8). Results: In each arm 191 pts were analyzed as intention-to-treat with a median FU of 13.75 yrs (0-22.9 yrs); 3/191 pts (1.6 %) in arm A and 16/191 pts (8.4 %) in arm B had a recurrence. 20-yrs PFS in arm A / B was 97 % (CI 96-99 %) / 92 % (CI 90-95 %), ( p = .0049). 20-yrs OS in arm A / B was 90 % (CI 86-94 %) / 88 % (CI 86-94 %), ( p = .83). 23/382 (6 %) pts have died, 22/23 not related to testis cancer, 1/23 died of a recurrence in arm B. 8/191 pts (4.2 %) in arm A and 4/191 pts (2.1 %) in arm B showed metachronous secondary testis cancer ( p = .26). 5/191 pts (2.6 %) in arm A and 4/191 pts (2.1 %) in arm B developed other malignancies. 170/382 questionnaires were evaluable (arm A: 95; arm B: 75). 45 pts were lost to FU. There were no significant differences comparing both treatment arms regarding potentially treatment-related late toxicities. However, excluding pre-existing complaints, ototoxicity (9/95 (9 %) vs. 4/75 (5 %) pts, p = .31) was reported more frequently in arm A. Excluding pre-existing neurological conditions, peripheral neuropathy of all grades was more frequently reported in arm A (15/95 pts; 16 % vs. 9/75 pts; 12 % pts; p = .48). Retrograde ejaculation occurred more frequently after RPLND (9/95 pts; 9% vs. 18/75 pts; 24 %, p = .01). Conclusions: After more than 13 yrs of FU, recurrences in non-risk factor selected pts with CS I NSGCT remain to be significantly more frequent with RPLND. No excess mortality due to secondary malignancies was observed. Late toxicities did not differ between 1 cycle of BEP and RPLND. Only retrograde ejaculation was observed significantly more frequent after RPLND. With long-term observation, 1 cycle of BEP has not only a high efficacy to prevent recurrence but also seems to be tolerated without clinically relevant long-term toxicity.

Age, growth and reproduction of the Asian sheephead wrasse Semicossyphus reticulatus in the western Seto Inland Sea, Japan

The Asian sheephead wrasse, Semicossyphus reticulatus, is the largest labrid in temperate waters around Japan. However, the growth pattern of this wrasse remains unclear. Age, growth, and reproduction of S. reticulatus specimens were investigated by sampling in the western Seto Inland Sea, Japan. Opaque ring marks formed on the marginal zone of sectioned otoliths during February–March, suggesting their validity for age estimates. The largest individual was a male, with a standard length (SL) of 591 mm, weight of 8.5 kg, and age of 17 years. Males had significantly larger SLs and older ages than females, and male gonads were histologically confirmed to have secondary testis structures retaining central lumens, suggesting monandric protogyny. The oldest S. reticulatus individual captured was estimated to be a 31-year-old male. The von Bertalanffy growth equation calculated from estimated age and SL was Lt = 489 (1 − e−0.12 (t + 1.75)), indicating considerably slow growth, particularly after the age of 10 years, which is similar to that of the California sheephead wrasse, Semicossyphus pulcher. The humpheads of S. reticulatus enlarged gradually as their body grew, often resulting in a conspicuous humphead, even in large females.

Reproductive characteristics of the humbug damselfish, Dascyllus aruanus, in Chuuk Lagoon, Micronesia

This study was conducted to investigate the reproductive characteristics of the humbug damselfish, Dascyllus aruanus, through the measurement of gonadosomatic indices (GSI) and histological examination of the gonads. Fish were collected from Chuuk Lagoon, Micronesia (7°27′N; 151°53′E), between August 2009 and July 2010. Overall, the functional sex ratio was approximately 1:1; however, there was a female bias in the smaller size range (35–40 mm standard length [SL]) and male bias in the larger size range (45–60 mm in SL). The process of oocyte development exhibited a group synchronous pattern, from the vitellogenic phase oocytes in the gonads following the two clutches of oocytes, as the primary growth stage and yolk vesicle stage. The testis with an ovarian lumen exists as a central slit, and the sperm ducts extend into the medial hilar region of the gonads, indicating that males of D. aruanus have a secondary testis of protogynous species. Monthly variations in the GSI and evolution of gonad status indicated that reproductive activity in this species occurs throughout the year in Chuuk Lagoon, Micronesia.

Diurnal dynamics of S‐phase entry of germ cells in the secondary testis of the bambooleaf wrasse (Pseudolabrus sieboldi)

The diversity of reproductive strategies found in fish is attributed to the adaptation of gametogenesis to different habitats. To date, however, information about the dynamics of male gametogenesis and its molecular mechanisms of control by the brain-pituitary-gonadal (BPG) axis, a well-known facet of the endocrine system in vertebrates, is not sufficient to explain the variation in spawning and regulatory mechanisms among species. The bambooleaf wrasse (Pseudolabrus sieboldi) is a protogynous hermaphrodite fish that shows clear diurnal fluctuations in gonadotropin gene expression and serum sex steroid levels associated with spawning. In this study, morphometrical and histological analyses were performed to determine the number of spermatogonial generations in the testis of the sex-changed male (secondary testis). In addition, the diurnal dynamics of S-phase entry of germ cells was explored by measuring the frequency of BrdU-incorporating germ cells at different times of day. We found that the bambooleaf wrasse spermatozoa were generated through nine spermatogonial generations, followed by meiotic divisions accompanied by loss of some spermatocytes and spermatids through apoptosis. BrdU analyses revealed a high frequency of entry into S-phase of undifferentiated type A spermatogonia at 03:00 hr. On the other hand, the frequency of spermatocytes at S-phase of the cell cycle decreased during 00:00-09:00 hr. This study demonstrates for the first time the daily fluctuations of S-phase entry of male germ cells in fish. These results will provide a useful foundation for understanding the roles of endocrinological and cytological regulation of fish spermatogenesis.

Life history characteristics of the protogynous parrotfish Calotomus japonicus from northwest Kyushu, Japan

In this study, we examined the life history characteristics of the parrotfish Calotomus japonicus, using individuals collected between May 2003 and May 2008 off the Nagasaki Peninsula in northwest Kyushu, Japan. Age determinations were performed using scales. Marginal increment analysis revealed that growth rings were formed annually around July. Growth in both sexes was fitted to the von Bertalanffy growth function (L∞ = 513, k = 0.28, t0 = 0.03, where L∞ is the theoretical asymptotic total length in mm, k is the growth rate coefficient and t0 is the theoretical time at zero length). Observed maximum age for both sexes was 8 years. We also characterized the reproductive biology of this species based on a gonadosomatic index and histological examinations of the gonads. The spawning season extends from July to October, with peak spawning activity occurring during July and August. Fish reach sexual maturity by the second year of life. Females are assumed to be multiple spawners, since we observed specimens with postovulatory follicles in ovaries containing either yolk globule oocytes or migratory nucleus oocytes. All males had secondary testes, which were characterized by the presence of an ovarian lumen structure and sperm sinuses in the gonadal wall. This indicates that all males, irrespective of whether they were initial or terminal phase males, had undergone a sexual transition. Sex change appears to occur during the spawning season, and thereafter sex-changed males are able to fertilize female eggs throughout the remainder of the current spawning season.

Hermaphroditic Characteristics of Gonad Morphology and Inferences Regarding Reproductive Biology in Caracanthus (Teleostei, Scorpaeniformes)

Caracanthus typicus and Caracanthus unipinna are small, obligate coral-dwelling, scorpaeniform fishes (F. Caracanthidae). In the majority of individuals in these two species, the male gonad is an ovotestis with several ovarian features, including an apparently nonfunctional gonadal lumen and the frequent presence of healthy-appearing oocytes. In addition, it has a feature typical of secondary testes in the form of peripheral sperm sinuses located within the ovotestis wall. These features collectively suggest that males in these two species arise secondarily from females. Males and females of both species also have an unusual gonad architecture in which the gametogenic tissue is almost entirely surrounded by a peripheral lumen for much of its length. Among females, maturing oocytes project into the ovarian lumen on stalks of stromal tissue and the periphery of the gonadal lumen is lined with a distinctive tall columnar epithelium consistent with a secretory function. Such ovarian features present in three other scorpaeniform species are associated with the release of eggs that are bound together in a gelatinous matrix to form floating egg masses. The presence of such features in female C. typicus and C. unipinna suggests that Caracanthus may have a similar mode of reproduction.

Gonad morphology, sexual development, and colony composition in the obligate coral-dwelling damselfish Dascyllus aruanus

Gonad morphology and colony composition support the existing supposition that the obligate coral-dwelling damselfish Dascyllus aruanus has a protogynous hermaphroditic sexual pattern. Adults had either an active ovary containing vitellogenic oocytes, an ovotestis, or a spermiated testis and were classified as adult female, hermaphrodite, or adult male, respectively. Among individuals having male function, the testis (or testis portion of the ovotestis) takes the form of an unrestricted spermatogonial lobular testis. Among hermaphrodites having an ovotestis, a small proportion of individuals had a gonad in which both the ovarian and testicular portions were inactive (inactive hermaphrodites), whereas the majority had a predominantly testicular ovotestis that contained spermatozoa (male-active hermaphrodites). The size range of individuals within gonadal classes indicates that all D. aruanus first develop an ovariform gonad. Some individuals then undergo ovarian maturation to become adult females while others develop testicular tissue to form an ovotestis and become male-active hermaphrodites. Subsequently, progressive loss of ovarian tissue results in the development of a secondary testis from an ovotestis with the retention of a residual, afunctional lumen among adult males. The wide size range of individuals having an ovotestis suggests that some hermaphrodites function as adult females before developing testicular tissue while other individuals do not pass through an adult female stage. If this is the case, D. aruanus exhibits a diandric protogynous hermaphroditic sexual pattern. The apparent prolonged retention of an ovotestis with both healthy oocytes and an ovarian-type lumen in a spermiated ovotestis, as well as a functional sex ratio of 1:1 for adult females:adult males plus male-active hermaphrodites also raises the possibility that D. aruanus may be capable of bidirectional sex change during the hermaphroditic stage. Such a capability would be highly adaptive for a species having limited mobility and unpredictable recruitment of new colony members resulting in unpredictable mating opportunities.

Gonadal development and non‐functional protogyny in a coral‐reef damselfish, Dascyllus albisella Gill

All gonads of the Hawaiian dascyllus Dascyllus albisella, irrespective of the final sex of individuals, developed an ovarian lumen and primary‐growth‐stage oocytes after an initially undifferentiated state. From this ovarian state or from more differentiated ovaries, some gonads redifferentiated into testes. None of 117 individuals examined had a gonad containing degenerating vitellogenic oocytes and proliferating spermatogenic tissue. Eleven individuals had gonads containing degenerating cortical‐alveolus‐stage oocytes and developing spermatogenic tissue. The size of these individuals overlapped with the female size range in which the majority of the females were still in the middle of the maturation process. They were absent from the larger size range where the majority of females had vitellogenic oocytes. This indicated that the transition toward maleness is likely to have occurred after the onset of cortical‐alveolus stage, but before final oocyte maturation and spawning as females. Therefore the protogynous pattern of gonadal development was non‐functional. There was no dimorphism in the sperm duct configuration, and all the testes were secondary testes reported for diandric, protogynous species with undelimited gonads. Very early development of an ovarian lumen appeared to have resulted in a secondary‐male configuration in all testes, although redifferentiation into males appeared to have occurred before sexual maturity and spawning as females.

Social organization and sexual pattern in the Mediterranean parrotfish Sparisoma cretense (Teleostei: Scaridae)

We examined the social organization and reproductive pattern of a population of Sparisoma cretense L. at Lampedusa Island (Italy). During the breeding season (July to September) individuals occur either in territorial or in non-territorial groups, which quantitatively differ with respect to use of space, sex-ratio and sexual activity. Territorial groups consist of one male plus one to three females, whereas in non-territorial groups as many as 54 fish share a common area. Among non-territorial groups, variations, in both sex-ratio and behavior, suggest they could represent either feeding aggregations or reproductive aggregations. Spawning, always in pairs, occurs daily in a short period of time before dusk and has been observed only in territorial groups. Group spawning has never been observed, but another alternative mating tactic, streaking on pair spawning, was recorded. In the non-breeding season fish do not aggregate in organized social units. Histological examination of gonads showed that adults are larger than 12 cm total length. Females have an asynchronous ovary, typical of species spawning several times during the breeding season. Males show secondary testes, indicating that their gonads develop ovaries as juveniles, which are later redifferentiated into functional testes. Histological and demographic data seem to indicate that, as in other species of this genus, prematurational sex-change occurs. The sexual pattern appears to be essentially gonochoristic, but the potential for sex-change is not excluded.

Doses to radiation sensitive organs and structures located outside the radiotherapeutic target volume for four treatment situations

This study documents dosage to radiation sensitive organs/structures located outside the radiotherapeutic target volume for four treatment situations: (a) head and neck, (b) brain (pituitary and temporal lobe), (c) breast and (d) pelvis. Clinically relevant treatment fields were simulated on a tissue-equivalent anthropomorphic phantom and subsequently irradiated with Cobalt-60 gamma rays, 6- and 18-MV x-ray beams. Thermoluminescent dosimeters and diodes were used to measure absorbed dose. The head and neck treatment resulted in significant doses of radiation to the lens and thyroid gland. The total treatment lens dose (300–400 cGy) could be cataractogegic while measured thyroid doses (1000–8000 cGy) have the potential of causing chemical hypothyroidism, thyroid neoplasms, Graves' disease and hyperparathyroidism. Total treatment retinal (400–700cGy) and pituitary (460–1000 cGy) doses are below that considered capable of producing chronic disease. The pituitary treatment studied consisted of various size parallel opposed lateral and vertex fields (4 × 4 through 8 × 8 cm). The lens dose (40–200 cGy) with all field sizes is below those of clinical concern. Parotid doses (130–1200 cGy) and thyroid doses (350–600 cGy) are in a range where temporary xerostomia (parotid) and thyroid neoplasia development are a reasonable possibility. The retinal dose (4000 cGy) from the largest field size (8 × 8 cm 2) is in the range where retinopathy has been reported. The left temporal lobe treatment also used parallel opposed lateral and vertex fields (7 × 7 and 10 × 10 cm). Doses to the pituitary gland (5200–6200 cGy), both parotids (200–6900 cGy), left lens (200–300 cGy) and left retina (1700–4500 cGy) are capable of causing significant future clinical problems. Right-sided structures received insignificant doses. Secondary malignancies could result from the measured total treatment thyroid doses (670–980 cGy). Analysis of three breast/chest wall and regional nodal irradiation techniques demonstrated a 25–50% decrease in secondary lung dose with use of independent collimation compared to use of custom alloy blocking material. However, it is unlikely that a reduction in secondary dose of this magnitude would reduce the risk of treatment sequellae. In four-field “box” pelvic irradiation, secondary testes dose may result in temporary (clamshell shield) or permanent azoospermia, but is unlikely to impair androgen production.

Sex differentiation and gonadal development in the diandric, protogynous wrasse, Thalassoma bifasciatum (Pisces, Labridae)

One hypothesis that would unify many of the apparently diverse patterns of gonadal differentiation in teleost fishes under a single conceptual scheme is that individuals develop in a female direction unless a masculinizing mechanism intervenes. We provided a descriptive test of this hypothesis in a diandric, protogynous wrasse in which males are produced through two, apparently different developmental sequences: ‘primary males’ develop testes as juveniles and remain male throughout life, while ‘secondary males’ develop ovaries as juveniles and later in adult life the functional ovary redifferentiates into a functional testis. The gonads of 128 individuals, from the smallest juveniles to full‐sized adults, were examined histologically. Gonads of the smallest juveniles were undifferentiated or contained young oocytes with no ovarian cavity and no testicular tissue. As individuals increased in size, the proportion of oocytic gonads increased. The distribution of gonad types for larger individuals suggested that a portion ofthese oocytic gonads developed into ovaries, while another portion lost its oocytic elements and became testes. These patterns supported the hypothesis that the gonads of all individuals, including primary males, passed through an initial female phase prior to differentiating into an ovary or testis. The structure of primary testes was not identical to the structure of secondary testes. The critical difference between the two types lay in the presence of a large central cavity in the latter that was not present in the former. Positional differences in the duct system were only found in the posterior region of the gonad and were the consequence of a lateral internal split in the secondary gonad resulting from confluence of the central cavity.

GONADAL STROMAL TUMORS, GONADOBLASTOMAS, EPIDERMOID CYSTS, AND SECONDARY TUMORS OF THE TESTIS IN CHILDREN

Gonadal stromal tumors generally are benign and hormonally silent. When hormonally active, they may cause either virilization or feminization, posing an endocrine threat to the prepubertal boy. Accurate diagnosis is essential to differentiate those tumors that require medical management from those best treated by surgical ablation and to distinguish the benign ones from the malignant. Leukemic infiltration is the most common secondary testis tumor; others are neuroblastoma, Wilms' tumor, and gonadoblastoma.

Gonadal structure and population characteristics of the protogynous goby Coryphopterus glaucofraenum

Protogynous hermaphroditism has been reported in two gobiid species within the genus Coryphopterus, including C. nicholsi from the temperate northeastern Pacific and C. personatus from the Caribbean. In a third species from the Caribbean, C. glaucofraenum, experimental groups were established and gonad structure of experimental individuals (collected off the southwest coast of Puerto Rico between February 1985 and June 1987) was subsequently examined histologically to determine the sexual pattern. Protogyny was confirmed in C. glaucofraenum. Sex change was either initiated or completed, typically by the largest female, in all-female groups held for 10 to 40 d. Ovarian, transitional, and testis structure were similar to that of C. nicholsi and C. personatus. No preformed testicular tissue was evident in the ovary proper and ovarian features were not retained in the sex-changed testis beyond the newly transformed stage. Secretory accessory gonadal structures associated with the testis and which develop at the time of sex change arose from precursive tissue masses associated with the ventral portion of the ovarian wall in the region of the common genital sinus. The rapid development and onset of function in these structures, generally preceding that of the associated developing testis, suggest that they may play an important role in sex change events and in advertising new male status. Based on observed similarities of ovarian, transitional and secondary testis structure in three protogynous Coryphopterus species, including one species isolated since the last closing of the American landbridge, it is probable that protogyny is an ancestral condition in this genus.

Protogynous hermaphroditism in the parrotfish,Calotomus japonicus

Sexual patterns of the parrotfish,Calotomus japonicus, were studied using fifteen specimens collected in February and April, 1990, near Makurazaki, Kagoshima Prefecture. The males ranged from 265 to 345 mm SL, and were larger than the females on average. Most females ranged from 202 to 260 mm SL, but a female of 305 mm SL was obtained. Sexual dichromatism was conspicuous. Histological examination of the gonads and low values of gonado-somatic indices of both males and females indicated that they were not in spawning season. It was concluded that C.japonicus is a protogynous hermaphrodite, because all male specimens had secondary testes. It was pointed out that the present species has a weak size-sex relationship. Because the specimens examined did not include primary males, it is suggested that primary males are relatively rare, if they occur at all.

Protogynous hermaphroditism in the wrasse Choerodon azurio.

The sexual pattern of a commercially important labrid fish Choerodon azurio was studied using specimens collected along the northern coast of Kyushu, Japan. Seventeen specimens collected on April 19, 1990, ranged from 164 to 315 mm in standard length. Specimens of 285 mm SL and larger were males and those smaller were females. Males were distinguishable from females by the following external appearances, i.e. squarish forehead, wider black band running obliquely on the side, reddish pectoral fin, more prominent iridescent blue spots on the latter half of the body, and deeper blue color of forehead and at the margin of caudal fin. Histological examinations of the gonads revealed that all of 6 males in the sample had secondary testes. It was concluded that Choerodon azurio is a protogynous hermaphrodite as well as many other labrid species. Although no primary males occur in the present specimens, it is necessary to study a larger number of specimens before concluding whether the species is a monandric or diandric protogynous hermaphrodite.

Anatomical features of sex inversion in the rainbow wrasse,Coris julis

Abstract In an anatomical study of 206 Coris julis (L.) taken in the Bay of Naples from September '81 to August '82, we found gonad organization to vary with the seasons, and that inversion occurs not only in empty gonads at the end of the reproductive period, but also in ovaries in active vitellogenesis, before the reproductive period. According to the criteria adopted by Reinboth (1975) and Dipper & Pullin (1979) for the histological differentiation of a primary into a secondary testis, we observed that of 21 individuals with a primary testis. 17 had an initial, and 4 had a terminal, colour pattern. Our data agree substantially with those of Bacci and Razzauti (1957), but differ notably from Reinboth's (1975).

Gonochorism and sex‐inversion in British Labridae (Pisces)

An investigation was made to compare the reproductive strategies of Crenilabrus melops, Labrus bergylta, Labrus ossifagus, Centrolabrus exoletus and Ctenolabrus rupestris. Fish were collected monthly and measurements were made of length, weight, age and colouration. Histological sections of the gonads were also prepared. Labrus bergylta and L. ossifagus are protogynous, the former monandric and the latter diandric, and a distinct colour change is associated with sex‐inversion in L. ossifagus. The other three species are gonochoristic and only C. melops exhibits sexual dimorphism which involves body colouration and size of the urino‐genital papilla.All five species undergo normal annual cycles of reproduction which compare with those described for other teleost species, but some differences were noted relating to the different reproductive strategies. L. bergylta females reached sexual maturity at the late age of six to nine years following earlier abortive maturation.In C. melops two types of male were found: the normal (type 1) males and a minority group (about 20%) termed type 2 males, which have complete female secondary sexual characteristics. Type 2 males also have very large testes and attain sexual maturity two years earlier than type 1 males. Their role in reproduction is unknown.Sexual inversion in L. bergylta and L. ossifagus occurs by atrophy of the oocytes and the gradual development of spermatogenetic cysts throughout the gonad. Primary and secondary testes can be distinguished histologically and male L. ossifagus with primary testes do not seem to take part in reproduction.

How Ecological and Genetic Factors Interact to Determine When Self-Fertilizing Hermaphrodites of Rivulus marmoratus Change into Functional Secondary Males, with a Reappraisal of the Modes of Intersexuality among Fishes

Hermaphrodites of Rivulus marmoratus, each in lifelong isolation, were exposed to one or another of the eight combinations of alternative temperatures, salinities, and light intensities, for the first 3-6 months from /4 blastoderm or earlier (early-rearing period). For the rest of their lives they were kept in 40% sea water at near 25? C and exposed to natural day lengths except for one artificial short-day season. Their life episodes and the conditions of all the eggs they laid were recorded. Hermaphrodites changed into secondary males in correlation with diminished egg laying and in response to one or another of the four annual, and one artificial short-day seasons, 1961-1965. Onset of this responsivity has a genotype-specific age-dependency. In two genetically unlike, uniparental, homozygous, isogenic groups (clones) of fish, early-reared at high temperature, the fish of one clone changed into males in response to the first two short-day seasons, those of the other in response to the last three, with no overlap. Within the same biotype (clone), this responsivity is advanced calendrically by early-rearing at high temperature; hermaphrodites early-reared at moderate or low temperature very rarely change into males and then only near the ends of lives prolonged by protected conditions. Scheduling of the sex changes was apparently unaffected by salinity, light intensity, or any of three morphoses (nonadaptive modifications), induced by early exposure to dim light and morphosis-specific salinity-temperature combinations. From year to year, the testicular zones of the ovotestes progressively increase in area more than the ovarian zones, expressing visibly the agedependent (time-measuring) factor in sex succession that fixes the onset of of the responsivity to short days. When the ratio of testicular to ovarian tissue becomes large enough, the next short-day season evidently triggers the rapid further proliferation of testicular tissue and the involution of ovarian tissue that ends egg laying, begins secondary-male coloration, and changes self-fertilizing hermaphrodites into functional secondary males by converting ovotestes into secondary testes. Testicular activity, measured by percentages of self-fertilized eggs laid, was much lower throughout the hermaphrodite phase of fish early-reared at low temperature as contrasted with high, but ovarian activity, measured by numbers of eggs laid per unit time, was similar between fish earlyreared at low and at high temperature. Testicular activity rose each year with the increase in day lengths from the annual minimum. Later in the annual daylength cycle, ovarian activity rose in response to the much longer days, and testicular activity was proportionately depressed, i.e. inhibited