Monitoring of the Reproductive Cycle in Captive-Bred Female Boa constrictor: Preliminary Ultrasound Observations

The Boa constrictor is one of the most common reptiles bred in captivity. To achieve a successful breeding season, thorough knowledge of the females’ reproductive activity is necessary. In this regard, information on the Boa constrictor is still rather scarce. The aim of the present study was to monitor the ovarian activity and the embryonic development of boas by ultrasound. We performed brief scans on thirty non-anaesthetized snakes using a portable ultrasound system and a 7.5–10 MHz linear array transducer (Esaote MyLab™ Classic). Ultrasound features, dimensions, and echogenicity of the preovulatory and postovulatory follicles were determined. As gestation progresses, the postovulatory follicle size increases, and the embryonic silhouette becomes increasingly recognizable. During the second month after ovulation, by using color Doppler, early embryos’ heart activity could be evaluated. It is possible to highlight vascular connections between the mother and the membrane covering the embryonic structures. Ultrasound also allows one to identify follicular regression or slugs (nonfertilized eggs) early. The present study suggests that ultrasound could be an excellent noninvasive technique to evaluate the reproductive activity of Boa constrictor, allowing us to precisely identify the correct time for mating, monitor embryo development and viability, and allow the early diagnosis of follicular regression.

New Evaluation of Postovulatory Follicle Degeneration at High-Temperature Regimes Refines Criteria for the Identification of Spawning Cohorts in the European Anchovy (Engraulis encrasicolus)

Accurate stock assessment estimates of fish resources are essential in fishery management. Wide fluctuations in abundance arising from variations in reproductive success are characteristic of many marine fish populations, including multiple spawner species. The proportion of females spawning per day is crucial in the application of egg production methods for spawning biomass evaluation and, usually, is assessed by postovulatory follicle (POF) method. Describing each degeneration stage of POF based upon its histological features allows for obtaining an aging key for postovulatory follicles. The commercially valuable European anchovy (Engraulis encrasicolus) was selected as a case study, which breeds during the summer in temperate waters (24 °C–25 °C). A collection of ovary slides, sampled in the central Mediterranean Sea during the spawning peak, provided a 24 h cycle coverage. These observations allowed us to evaluate the duration of each POF stage at water temperature experienced by anchovy in the study area. Present results demonstrated the POF degeneration progress at a faster rate than reported by previous investigations, carried out in cooler oceanic waters. Furthermore, the present study displayed the presence of two anchovy spawning cohorts sampled along a 24-h cycle. Therefore, this study not only provides useful insight for more accurate POF degeneration evaluation in temperate waters, but also suggests that current estimates should be complemented with validation studies according to different temperature regimes.

Secreted Protein, Acidic and Rich in Cysteine (SPARC) and Thrombospondin in the Developing Follicle and Corpus Luteum of the Rat

In adult mammals, growth of new vasculature from extant blood vessels (angiogenesis) is rare in the absence of pathology. However, nonpathogenic angiogenesis occurs in the cycling ovary when the avascular postovulatory follicle transforms into a highly vascularized corpus luteum (CL). To improve our understanding of molecular mechanisms that regulate nonpathogenic vascular growth, we characterized the expression of two secreted matricellular proteins associated with angiogenesis, SPARC and thrombospondin (TSP), in postovulatory preluteal follicles and CL of hormone-primed immature rats. By indirect immunofluorescence with specific antibodies, we found SPARC in the cytoplasm of granulosa cells and thecal cells of preluteal follicles, in connective tissue cells of the ovarian interstitium, and in the oocyte nucleus. Administration of a luteinizing stimulus (chorionic gonadotropin) increased the expression of SPARC in granulosa cells. TSP was prominent in the basement membranes of growing follicles. Many cells in the early vascularizing CL expressed both SPARC and TSP. Neovascularization of CL was accompanied by expression of SPARC in nascent vessels and concentration of TSP in central avascular areas. In mature CL, steroidogenic luteal cells expressed both SPARC and TSP. Luteal cells of regressing CL retained SPARC to a variable degree but did not express TSP. The observed changes in expression of SPARC and TSP during development of the CL support distinct roles for these matricellular proteins in nonpathological morphogenesis and angiogenesis.