The external appearance of brood fish has long been used to assess the stage of sexual development. In some species, males change in appearance during the spawning season (e.g., vivid breeding colors in cichlids, hooked jaw in salmon, and roughened texture of the pectoral fins or head of cyprinids). These physical changes make it relatively easy to identify sexually mature males. However, secon...

No instance of survival of spleen homeografts beyond the usual taking and persistence for 1 or 2 weeks common to most homeografts has been observed, although the possible advantages of consanguinity, age, and splenectomy were fully utilized. This is in sharp contrast to thyroid, sex gland, and adrenal cortex homeografts, with which one may expect 10 per cent to survive the 30 day period. It sug...

Parasites have significant effects on the fitness of their hosts. We used an intestinal nematode, Ascaridia galli, as an experimental treatment of young male Red Jungle Fowl (Callus gallus) to investigate the effect of this parasite on their growth and development through sexual maturity. After treatment, 26% of those fed parasites and 31% of controls became infected. Infected males had lower b...

We examined the emergence of a critical component of sex, response to sexual signals-phonotaxis-in male and female túngara frogs (Physalaemus pustulosus). We determined the ontogenetic trajectories of phonotactic responses as animals developed from metamorphic froglets to reproductive adults. The results demonstrated that species-typical phonotaxis emerges quite early during postmetamorphic dev...

Reproductive biology is important in formulating management interventions for fish stocks. Limits on catch size are established based the identified at first sexual maturity of target species, which can be accurately determined through histological analysis gonads. The study investigated reproductive characteristics endangered Sardinella tawilis and analysis. Between 2017 2018, 312 samples with...

Sex, age and sexual maturation are key biological parameters for aspects of life history and are fundamental information for assessing demographic changes and the reproductive viability and performance of natural populations under exploitation pressures or in response to environmental influences. Much of the information available on the reproductive condition, length at sexual maturity and sex ...

The relative growth of a number of morphological dimensions of the South American freshwater crab Trichodactylusborellianus (Trichodactylidae) were compared and related to sexual dimorphism. Crabs were collected from ponds in the Middle Paraná River in Argentina. A regression model with segmented relationship was used to test for relative growth between these measurements where breakpoints infe...

This work presents information regarding the biology and state of conservation of an endangered annual fish Hypsolebias antenori. Fish were captured from small seasonal pools located in Northeastern Brazil. The total body length, body mass, sex ratio, first sexual maturity were investigated. The sampled population showed sexual dimorphism. There was a predominance of females (60%) over males (4...

This article examines associations between fat bodies and reproductive dysfunction that were prevalent in medical, midwifery and other literature in early modern England. In a period when fertility and successful reproduction were regarded as hugely important for social, economic and political stability such associations further contributed to negative attitudes towards fat bodies that were fue...

Sex differences in age- and puberty-related maturation of human brain structure have been observed in typically developing age-matched boys and girls. Because girls mature 1-2 years earlier than boys, the present study aimed at assessing sex differences in brain structure by studying 80 adolescent boys and girls matched on sexual maturity, rather than age. We evaluated pubertal influences on me...