Rossana Brizzi

Comparative biology of sperm storage in female salamanders.

Females in seven of the ten families of salamanders possess cloacal glands called spermathecae that store sperm. The annual cycle of sperm storage has been studied by light and electron microscopy in eight species representing five families. In these taxa, we recognized 14 characters associated with the spermathecae and traced their evolution on a phylogeny of salamanders based upon other characters. The plasticity and phyletic significance of the spermathecal characters varied greatly. Plethodontids have complex spermathecae while other families possess simple spermathecae; thus, this character has phyletic value as well as being highly conserved within the Salamandroidea. Other characters, such as carbohydrate histochemistry, are highly plastic and show no obvious phyletic trends. The significance of some of these variable characters, such as duration of sperm storage, is apparent only after including in the analysis other aspects of the reproductive cycle, such as length of the mating season. Additional comparative studies, employing the protocol used in this paper, will help further clarify the relationships between phyletic and functional variability in sperm storage mechanisms in salamanders.

Serous cutaneous glands in Phyllomedusa hypochondrialis (Anura, Hylidae): secretory patterns during ontogenesis.

Three syncytial gland types (Ia, Ib, and II ) have been described in the skin of larval, juvenile and adult Phyllomedusa hypochondrialis, which share the ultrastructural traits common to the serous secretory units of anuran skin, although each manufactures a peculiar product. Type la secretion consists of dense granules provided with a peculiar substructure, type Ib of vesicles holding a lucent material, type II of lipid deposits. None of the developmental stages investigated showed intermediate features between any of the three cutaneous products, which accumulate in the syncytial cytoplasms of the secretory units following different biosynthetic pathways, consistent with each gland type. These findings confirm previous results on adult specimens of P. hypochondrialis and P. sauvagei and stress the polymorphism of the serous glands in the genus Phyllomedusa. This morphological variability reflects the wide adaptive flexibility of serous glands in anurans.

Interleukin-1 in reproductive strategies

SUMMARY Evolutionary studies on different classes of vertebrates could help clarify the role of cytokines in acceptance of the embryo by the maternal tissues. This review focuses on the cytokine interleukin‐1 (IL‐1) and reports on its presence in the female reproductive tract of species with different reproductive strategies, that is, viviparity, oviparity, and ovuliparity. Unlike oviparity and viviparity, ovuliparity does not involve any contact between paternal‐derived fetal antigens and maternal tissues, because eggs are released unfertilized in the external environment. Therefore, we consider ovuliparity a natural negative control for mechanisms of materno‐fetal immunotolerance. The goal of this review is to discuss the role of the IL‐1 system in the acquisition of the ability to retain the embryo in the female genital tract during the transition from ovuliparity to viviparity.

Spermathecae of Salamandrina terdigitata (Amphibia: Salamandridae): Patterns of sperm storage and degradation

The spermathecae of female Salamandrina terdigitata were observed using light and transmission electron microscopy during the fallspring period of sperm storage and secretory activity and during the summer stasis. When sperm are stored inside the spermathecae, the product synthesized by spermathecal epithelial cells is exported into the lumen, where it bathes the sperm. During sperm storage some spermatozoa undergo degradation by the spermathecal epithelium. This process, which includes sperm capture by the apical microvilli, formation of endocytic vacuoles and production of lysosomes, becomes prominent shortly after oviposition. In many instances, cells filled with vacuolized spermatozoa and/or residual bodies undergo desquamation from the spermathecal epithelium and enter the lumen together with residual sperm. Desquamated cells, together with residual sperm, are a common feature in the spermathecal lumina at the end of the egg‐laying season.

Serous cutaneous glands of Argentine Phyllomedusa Wagler 1830 (Anura Hylidae): secretory polymorphism and adaptive plasticity

An ultrastructural study has been carried out on the cutaneous serous glands in the Argentine hylids Phyllomedusa sauvagei Boulenger 1882 and P. hypochondrialis Boulenger 1882. Both species possess type I serous units, which are representative of the usual serous glands in anurans, and type II units, peculiar to the genus Phyllomedusa Wagler 1830. Type I secretory units were further characterized as type Ia and Ib, on account of the morphology of their specific products. Type Ia secretory materials consist of spheroidal granules (4–6 μm in diameter), which are compact in P. sauvagei and provided with a mesh-like substructure in P. hypochondrialis. Type Ib serous deposits in P. sauvagei are also granules, which exhibit variable density, irregular shape, and are usually larger (up to 15 μm in diameter), whereas in P. hypochondrialis they are even wider vesicles (up to 20 μm), holding a finely dispersed material. No intermediate forms were detected between these features, and therefore the type I secretory u...

Serous gland dimorphism in the skin of Melanophryniscus stelzneri (Anura: Bufonidae).

Two serous gland types (I and II) in the skin of the Argentine toad Melanophryniscus stelzneri were discovered using light and electron microscopy. Glands of the two types differ in several traits: features of the products (both mature and immature), organelles involved in biosynthesis, and paths of serous maturation. No consistent differences, however, were detected between the myoepithelial sheaths encircling the secretory units. Type I glands manufacture vesicles containing a single dense body with a repeating substructure and conform to the fundamental secretory line of bufonid skin, a secretory line involved in biosynthesis of steroids. Type II glands synthesize granules of varying densities and seem to belong to a line of glands that secrete proteinaceous products. The occurrence of the two serous gland types in Melanophryniscus stelzneri is discussed in a comparison with current literature on the morphofunctional characteristics of anuran poison glands, which perform both regulative and defensive roles. It is suggested that di‐ or polymorphism in serous glands is an adaptive trait that allows differential release of active molecules on the body surface. J. Morphol. 237:19–32, 1998.

Secretory polymorphism and serous cutaneous gland heterogeneity in Bufo granulosus (Amphibia, Anura).

Three types of secretory products (a, b and c) in the poison glands of the Argentine toad Bufo granulosus have been detected under light microscope. The type a secretory product consists of granules of homogeneous density, type b of vesicles with a translucent compartment and type c of granules of varying density. Subsequent transmission electron microscope analysis disclosed obvious similarities in the secretory pathways of type a and c granules; the differences detected under light microscope are due to the functional phases observed. On the contrary, production of type b secretory vesicles involves a distinctive pathway. Therefore, two classes of glands (I and II) have been identified. Glands of the first class are typical of bufonid toads and produce granules provided with repeating substructure; glands of the second class, which manufacture a lucent product, are unusual in the family Bufonidae. Ultrastructural differences, consistent with the two gland classes, have also been described in the myoepithelia. The myocytes ensheathing class I secretory units possess striking cytoskeletal specializations, whereas those of class II glands are rich in sarcoplasmic reticulum. The distinctive ultrastructural traits detected in these myoepithelial cells have been compared with the results of previous studies on the dimorphic serous glands of Bombina. Findings point to the use of pharmacological treatment on the skin of anurans with different classes of serous glands to elicit differential secretory discharge.

Sperm morphology of salamandrids (Amphibia, Urodela): implications for phylogeny and fertilization biology

Mature spermatozoa belonging to four salamander species, Salamandrina terdigitata, Triturus alpestris, Triturus carnifex and Triturus vulgaris, have been investigated by electron microscopy. The sperm ultrastructure of these species was compared with that of previously examined urodeles (36 species and 20 genera) and with that of anurans and caecilians. Many phylogenetic considerations may be inferred as a consequence of comparative spermatology. Urodela appears to be a monophyletic order characterized by three sperm synapomorphies: the acrosomal barb, nuclear ridge and marginal filament. Cryptobranchoidea are confirmed to form a monophyletic suborder having two synapomorphic characters: absence of mitochondria in the tail, and cylindrical shape of the tail axial rod. Within the family Salamandridae, sperm morphology confirms the phylogenetic distance between Salamandrina and Triturus, as already pointed out on the basis of molecular and morphological characters. The very complex ultrastructure of spermatozoa confirms a previous opinion that internal fertilization is the ancestral condition of the Amphibia.

Interleukin 1 in Oviductal Tissues of Viviparous, Oviparous, and Ovuliparous Species of Amphibians

Abstract In previous reports, we have shown that interleukin 1 (IL1), a cytokine associated with implantation in mice, is also expressed in reproductive tissues of viviparous squamate reptiles and cartilaginous fishes. In the present study, we investigated the expression of IL1B and its functional membrane receptor type I (IL1R1) in amphibians, a class of vertebrates that is characterized by different reproductive modes, including internal and external fertilization. In particular, we investigated the oviductal tissues of the aplacental viviparous Salamandra lanzai, the oviparous Triturus carnifex, and the ovuliparous Bufo bufo. In immunohistochemistry with anti-human IL1B and IL1R1 polyclonal antibodies we found that in S. lanzai, most cells in the uterine mucosa were immunoreactive for IL1B and IL1R1. In T. carnifex, IL1B and IL1R1 were present in ciliated luminal cells, and there was evidence of IL1B in glandular cells. In B. bufo, the expression of IL1B and IL1R1 was limited to the apical cytoplasm of the ciliated oviductal cells. Western blot analysis showed that a putative mature form of IL1B, similar to that seen in mammals, was present in the oviductal tissues of S. lanzai, whereas different forms, which probably correspond to an inactive pro-IL1B protein, were found in T. carnifex and B. bufo. A band that corresponded to the predicted 80-kDa human IL1R1 was found in S. lanzai and T. carnifex. Although the present study shows that IL1B and IL1R1 expression occurs in all reproductive modes, the differential expression patterns noted between ovuliparity and oviparity and viviparity may reflect the different roles of IL1 in the various reproductive modes.

Cutaneous serous glands in South‐American anurans: An ultrastructural comparison between hylid and pseudid species

Abstract An ultrastructural analysis of the secretory processes in serous cutaneous glands of some hylid species (Scinax acuminata, S. fuscovaria, S. nasica and Hyla nana) and one pseudid species (Pseudis paradoxa) revealed similar features, from the early steps to advanced maturational phases. The most consistent and peculiar trait was the occurrence of granules with repeating substructures, resulting from multi‐focal condensation of the dispersed material contained in the Golgian vesicles, which represent the early feature of the secretory activity. Since the ultimate granule features derive from comparable pathways of sequential processes ‐ including early secretory activity and maturation ‐ the similar repetitive substructure is proposed as a trait informative on the taxonomic relationships between the species considered. Comparable granule features in serous glands of different species confirm the close systematic framing of Hyla and Scinax among Hyli‐nae, while stressing phylogenetic relationships between the hylid and pseudid families.