The potential toxicity of microplastics is a growing concern for the scientific community. The loggerhead sea turtle (Caretta caretta) is particularly inclined to accidently ingest plastic and microplastic due to its long-life cycle features. The possible transfer of microplastics from the female to the eggs should be investigated. The present study investigated the presence of microplastics in yolk and liver samples evaluating the number of melanomacrophages in the hepatic tissue as a possible biomarker of microplastics impact on the embryonic health status. The biometric parameters and liver histological analysis of 27 and 48 embryos (from two different nests respectively) at the 30 stage of development were analyzed. Raman Microspectroscopy was performed to identify the microplastics after alkaline digestion (10% KOH) of yolk and portion of liver from 5 embryos at the 30 developmental stage per nest. Microplastics were found in yolk and liver of loggerhead sea turtles at late embryonic stage for the first time. All microplastics were smaller than 5 μm and were made of polymers and colors suggesting their diverse origins. A total number of 21 microplastics, with dimensions lower than 5 μm, were found between the two nests (11 and 10 microplastics respectively). Only two shape categories were identified: spheres and fragments. The most frequent polymers observed were polyethylene, polyvinyl chloride and acrylonitrile butadiene styrene (31.5%, 21.1% and 15.8% respectively). Despite the eggs showing a higher number of microplastics in yolk samples than liver (15 and 6 microplastics in yolk and liver respectively), a positive correlation was observed only between the number of melanomacrophages (r = 0.863 p < 0.001) and microplastics in the liver. This result may suggest that microplastics could exert some effects on the hepatic tissues. Future studies should investigate this aspect and the possible relation between microplastics and other stress biomarkers.

Elasmobranchs have an ancestral reproductive system, which offers insights into vertebrate reproductive evolution. Despite their unchanged design over 400 million years, they evolved complex mechanisms ensuring reproductive success. However, human activities induced a significant decline in elasmobranch populations worldwide. In the Mediterranean basin, the smooth-hound shark (Mustelus mustelus) is one of the species that are considered vulnerable to human activities. Conservation efforts necessitate a thorough understanding of its reproductive strategy. This study focused on mature male specimens of smooth-hound sharks that were captured in the Adriatic area and successively analyzed to provide, for the first time, a histologically detailed description of testicular development in the species. Seven phases of the spermatogenesis process were identified, along with the macromolecular characterization of cells obtained using Fourier-transform infrared imaging. Histological analysis showed structural and cellular features similar to those documented in the spermatocysts of other elasmobranchs. The examination of the evolution and migration of both germinative and Sertoli cells at each phase revealed their close connection. Furthermore, different expression levels of lipids, proteins, and phosphates (DNA) at each spermatogenesis stage were observed. This research provided new information on spermatogenesis in the common smooth-hound shark, which is crucial for conservation efforts against population decline and anthropogenic pressures.

The Atlantic blue crab (Callinectes sapidus Rathbun, 1896) is a euryhaline and eurythermal species native to the Atlantic coasts of the Americas. Although its widespread distribution across the Mediterranean basin is well documented, information on its reproductive patterns remains limited. This study focused on the combination of both macroscopic and histologic characterization of ovarian developmental stages in female blue crabs along the north-central Italian Adriatic coast, within the spawning period. Samples were collected off the coast of Ancona, in collaboration with local fishermen, between September and November 2023. For each specimen, sex and biometric parameters were recorded to determine the sex ratio, while size distribution and gonadosomatic index (GSI) were calculated for female specimens. Ovary samples and eggs sponge were collected to determine the ovarian developmental stage and fecundity respectively. Results showed females as the dominant sex throughout the sampling period, with males being extremely rare. The collapse of female catches in early November, alongside the consistent presence of ovigerous females and the strong female-biased sex ratio, identified this area as a spawning ground. These findings align with reproductive patterns observed in the species' native range and other Mediterranean areas. Moreover, GSI values and fecundity indexes associated with macroscopic and histological examination of ovarian stages suggested that the end of the reproductive season corresponded to mid-November.

The Adriatic Sea is a critical neritic habitat for juvenile and adult female loggerhead sea turtles (Caretta caretta), where intense anthropogenic pressures and environmental stressors may influence their reproductive biology. Knowledge on the onset of puberty in this population is limited by scarce information on the sub-adult stage, a transitional phase in which reproductive competence is acquired. This study integrated histological analysis and Fourier-transform infrared (FTIR) imaging spectroscopy to provide both structural and biochemical characterization of folliculogenesis, with emphasis on vitellogenesis, in C. caretta from the north-central Adriatic Sea. Histological analysis determined the progression of follicle development, while FTIR imaging, a label-free and spatially resolved technique, mapped the distribution of proteins, lipids, and nucleic acids across ovarian compartments. Logistic regression estimated the size at which 50% of females are sexually mature (L₅₀) at 58.54 cm Curved Carapace Length (CCL). Based on this value, 60% of sub-adult females were already mature, indicating earlier puberty than previously inferred from macroscopic criteria. These preliminary results, along with reports of sporadic nesting in the Adriatic, raise the question of whether this basin may host further nesting events in the future. FTIR imaging proved to be a powerful tool for reproductive biology in non-model marine vertebrates.