An ultrastructural study was carried out on the epidermis of Agalychnis callidryas tadpoles during limb development. Larval epidermis consisted of four cell layers: basal, lower intermediate, upper intermediate, and surface or apical layers. Basal cells represented the stem compartment of intermediate cells: both belong to the skein cell (SC) lineage, described in several anuran species, on account of the conspicuous intracytoplasmic tonofilament bundles. Apical cells were secretory in nature and released mucus on the body surface. Intermediate SCs exhibited a hydrated central cytoplasm and peripheral tonofilament bundles. They closely resembled the epidermal ball-like cells, Kugelzellen (KZn) of Xenopus laevis tadpoles, and possibly shared their turgor-stiffness properties. In A. callidryas, the stratification of intermediated SCs on their stem cell layer provided the chance to study their cytodifferentiation in a suitable sequence, until basal cell differentiation shifted toward the keratinocyte lineage in premetamorphic stages. Present data assign A. callidryas to the anuran species with a constitutive SC population in larval epidermis, and demonstrate that KZn express the ultimate specialization of such cell line. SCs were arranged in the fashion of a random-rubble stone groundwork, and possessed long processes. These cytoplasmic outgrowths contained a tonofilament axial rod and held together contiguous cells. Ultrastructural findings suggest that this complex structure may impart compressive as well as sliding strengths to the larval epidermis, representing a possible adaption to the fresh water environment. Anat Rec, 294:1601Rec, 294: -1610Rec, 294: , 2011. V V C 2011 Wiley-Liss, Inc.
In cotton top tamarins (Saguinus oedipus), scent glands have been mostly studied in females from museum collections. This work aims to extend the investigation to male specimens, introducing a novel source of skin samples. Two adult males from zoo populations, one intact and one castrated, were immediately frozen after natural death. Skin samples were later collected at the thawing onset, soaked with cold fixative and processed for light microscopy. Sebaceous units of scent glands showed phasic secretory activity in the intact male and marked fibrosis in the castrated male. It appears, therefore, that light microscopy samples from frozen tissues provide detailed features that can disclose distinctive traits in specimens characterized by different hormonal balances.
The cloacal anatomy of the palmate newt, Triturus helveticus, was studied in both sexes using light and scanning electron microscopes. The female cloaca is characterized by the occurrence of rugae and folds. Two folds are especially prominent in the region where the spermathecal tubules open into the cloaca. In addition to sperm storage structures, vent glands are obvious in the connective tissue around the cloacal orifice. Their pores occur externally to the cloacal borders, thus suggesting that these glands are a possible source of mating pheromones. Typical features of the male cloaca are: a ciliated epithelium; a cloacal tube dorsal and separate from the anterior cloacal chamber; a broad pseudopenis and wide lateral recesses in the cloacal chamber. Four main types of cloacal glands are recognized in males (dorsal, pelvic, Kingsbury's, and ventral gland). Quite unusual is the occurrence of two distinct types of dorsal glands, possibly related to the production of different pheromonal substances. These glands in the male, together with the occurrence of vent glands in the female, are proposed as cloacal specializations for the production of unequivocal species-specific sex attractants.
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