The saccus vasculosus of the neotropical cichlid fish Cichlasoma dimerus: characterization, developmental studies and its response to photoperiod.

The saccus vasculosus is an organ present in gnathostome fishes, located ventral to the hypothalamus and posterior to the pituitary gland, whose structure is highly variable among species. In some fishes, this organ is well-developed; however, its physiological function is still under debate. Recently, it has been proposed that this organ is a seasonal regulator of reproduction.

Integrating morphology and physiology of the key endocrine organ during tadpole development: The interrenal gland.

Indirect development is widespread in anurans and is considered an ancestral condition. The metamorphosis of larvae into juveniles involves highly coordinated morphological, physiological, biochemical, and behavioral changes, promoted by the thyroid hormone and interrenal corticosteroids. Stress response to environmental changes is also mediated by corticosteroids, affecting the timing and rate of metamorphosis and leading to great developmental plasticity in tadpoles.

Aberrant RET expression affects normal mammary gland post-lactation transition, enhancing cancer potential.

RET is a receptor tyrosine kinase with oncogenic potential in the mammary epithelium. Several receptors with oncogenic activity in the breast are known to participate in specific developmental stages. We found that RET is differentially expressed during mouse mammary gland development: RET is present in lactation and its expression dramatically decreases in involution, the period during which the lactating gland returns to a quiescent state after weaning.

Eye ontogeny in Pleurodema bufoninum: A comparison with Pleurodema somuncurense (Anura, Leptodactylidae).

Vision is one of the main sensory systems in amphibians, and the eye structure is highly associated with habitat conditions. The ontogeny, as well as the adult structure, of the eye has been studied in only a few species. The life change after metamorphosis is accompanied by changes in the visual environment.

Post-metamorphic development of skin glands in a true toad: Parotoids versus dorsal skin.

Chemical defenses in amphibians are a common antipredatory and antimicrobial strategy related to the presence of dermal glands that synthesize and store toxic or unpalatable substances. Glands are either distributed throughout the skin or aggregated in multiglandular structures, being the parotoids the most ubiquitous macrogland in toads of Bufonidae. Even though dermal glands begin to develop during late-larval stages, many species, including Rhinella arenarum, have immature glands by the end of metamorphosis, and their post-metamorphic growth is unknown.

A comparative ultrastructural analysis of spermatozoa in Pleurodema (Anura, Leptodactylidae, Leiuperinae).

This study describes the spermatozoa of 10 of the 15 species of the Neotropical frog genus Pleurodema through transmission electron microscopy. The diversity of oviposition modes coupled with a recent phylogenetic hypothesis of Pleurodema makes it an interesting group for the study of ultrastructural sperm evolution in relation to fertilization environment and egg-clutch structure. We found that Pleurodema has an unusual variability in sperm morphology.

Odorous secretions in anurans: morphological and functional assessment of serous glands as a source of volatile compounds in the skin of the treefrog Hypsiboas pulchellus (Amphibia: Anura: Hylidae).

Serous (granular or venom) glands occur in the skin of almost all species of adult amphibians, and are thought to be the source of a great diversity of chemical compounds. Despite recent advances in their chemistry, odorous volatile substances are compounds that have received less attention, and until now no study has attempted to associate histological data with the presence of these molecules in amphibians, or in any other vertebrate. Given the recent identification of 40 different volatile compounds from the skin secretions of H.

Morphological Changes in Skin Glands During Development in Rhinella Arenarum (Anura: Bufonidae).

Avoiding predation is critical to survival of animals; chemical defenses represent a common strategy among amphibians. In this study, we examined histologically the morphology of skin glands and types of secretions related to chemical skin defense during ontogeny of Rhinella arenarum. Prior to metamorphic climax the epidermis contains typical bufonid giant cells producing a mucous substance supposedly involved in triggering a flight reaction of the tadpole school.

Environmentally-relevant concentrations of atrazine induce non-monotonic acceleration of developmental rate and increased size at metamorphosis in Rhinella arenarum tadpoles.

Despite of the various studies reporting on the subject, anticipating the impacts of the widely-used herbicide atrazine on anuran tadpoles metamorphosis remains complex as increases or decreases of larval period duration are almost as frequently reported as an absence of effect. The aim of the present study was to examine the effects of environmentally-relevant concentrations of atrazine (0.1, 1, 10, 100, and 1000μg/L) on the timings of metamorphosis and body size at metamorphosis in the common South American toad, Rhinella arenarum (Anura: bufonidae).

New insights into sexually dimorphic skin glands of anurans: the structure and ultrastructure of the mental and lateral glands in Hypsiboas punctatus (Amphibia: Anura: Hylidae).

Many anuran species are characterized by sexually dimorphic skin glands. These glands often are concentrated on specific areas, such as the mental region, flanks, or the nuptial pads. We studied the histology and histochemistry of mental and lateral glands in Hypsiboas punctatus, and compared them to skin from other body regions.

Effects of androgenic gland ablation on growth and reproductive parameters of Cherax quadricarinatus males (Parastacidae, Decapoda).

This work investigates the effects of androgenic gland (AG) ablation on the structure of the reproductive system, development of secondary sexual characters and somatic growth in Cherax quadricarinatus males. The AG ablation, which was performed at an early developmental stage (initial weight: 1.85±0.

Structure of the kidney of Bufo arenarum: intermediate segment, distal tubule and collecting tubule.

The ultrastructure of the intermediate segment (IS), distal tubule and collecting tubule (CT) of the south american toad Bufo arenarum, was studied by light and transmission electron microscopy. The IS is composed of cubical ciliated cells which propel the urine along the renal tubule. The distal tubule is divided into two portions: the early distal tubule (EDT) and the late distal tubule (LDT).

Ultrastructural characteristics of the lung of Melanophryniscus stelzneri stelzneri (Weyenberg, 1875) (Anura, Bufonidae).

The lung of the toad, Melanophryniscus stelzneri stelzneri was studied using scanning and transmission electron microscopy. In M.s.