Is there a role for endocannabinoids in sperm–oviduct interaction?

The endocannabinoid system (ECS) has been found in reproductive cells and tissues in several mammals. Spermatozoa are able to respond to anandamide, and the oviduct is able to synthesize and modulate the concentration of this endocannabinoid along the isthmic and ampullary regions. The main aim of this study was to understand whether the ECS has a role during sperm storage and release within the oviduct in cattle. Data showed that 1) the endocannabinoid receptors 1 and 2 (CB1 and CB2) are present in bovine spermatozoa both in the initial ejaculate and in spermatozoa bound to the oviduct in vitro; 2) CB1 receptor is still detectable in spermatozoa released from the oviduct through penicillamine but not in those released through heparin; 3) arachidonylethanolamide (AEA) does not affect sperm viability, whereas it depresses sperm progressive motility and kinetic values; 4) sperm–oviduct binding and release in vitro are not influenced by AEA; 5) AEA depresses sperm–zona pellucida (ZP) binding; 6) binding of heparin-capacitated spermatozoa to the ZP is not affected by AEA; 7) N-acylphosphatidylethanolamine-selective phospholipase D, the main enzyme involved in anandamide synthesis, is expressed in oviductal epithelial cells. In conclusion, secretion of AEA from epithelial cells might contribute to the oviduct sperm-reservoir function, prolonging the sperm fertile life through the depression of motility and capacitation. Capacitation signals, such as heparin, that promote sperm release, might remodel the sperm surface and cause a loss of the sperm sensitivity to AEA

ULTRASTRUCTURAL STUDIES ON DEVELOPING FOLLICLES OF THE SPOTTED RAY TORPEDO MARMORATA

Light and ultrastructural investigations on sub-adult and adult sexually mature females, demonstrates that in Torpedo marmorata folliculogenesis starts in the early embryo and that the two ovaries in the adult contain developing follicles of various sizes and morphology. Initially, the follicle is constituted by a small oocyte, surrounded by a single layer of squamous follicle cells. The organization is completed by a basal lamina and, more externally, by a theca, that at this stage is composed by a network of collagen fibers. As the oocyte growth goes on, during previtellogenesis and vitellogenesis, the organization of the basal lamina and of the oocyte nucleus does not change significantly. The basal lamina, infact, remains acellular and constituted by fibrils intermingled in an amorphous matrix; the nucleus always shows an extended network of chromatin due to the lampbrush chromosomes, and one or two large nucleoli. By contrast, the granulosa (or follicular epithelium), the ooplasm, and the theca cells significantly change. The granulosa shows the most relevant modifications becoming multi-layered and polymorphic for the progressive appearance of intermediate and pyriform-like cells, located respectively next to the vitelline envelope, or spanning the whole granulosa. The appearance of intermediate cells follows that of intercellular bridges between small follicle cells and the oocyte so that one can postulate that, as in other vertebrates, small cells differentiate into intermediate, and then pyriform-like cells, once they have fused their plasma membrane with that of the oocyte. Regarding the ooplasm, one can observe as in previtellogenic follicles, it is characterized by the presence of intermediate vacuoles containing glycogen, while in vitellogenic follicles by an increasing number of yolk globules. The theca also undergoes significant changes: initially, it is constituted by a network of collagen fibers, but later, an outermost theca esterna containing cuboidal cells and an interna, with flattened cells, can be recognized. The role of the different constituents of the ovarian follicle in the oocyte growth is discusse

Surface glycoproteins bearing alpha-GalNAc terminated chains accompany pyriform cell differentiation in lizards

The present investigation demonstrates that in squamate reptiles, as already reported for Podarcis sicula (Andreuccetti et al., 2001), the differentiation of pyriform cells from small, stem follicle cells is characterized by the progressive appearance on the cell surface of glycoproteins bearing alpha-GalNAc terminated O-linked side chains. Using a lectin panel (WGA, GSI-A4, GSI-B4, PSA UEA-I, PNA, Con-A, DBA, LCA, BPA, SBA), we demonstrated that, during previtellogenesis, the pattern of distribution of DBA binding sites over the follicular epithelium dramatically changes. In fact, binding sites first appear in follicular epithelium at the time that small cells begin to differentiate; in such follicles, labeling is evident on the cell surfaces of small and intermediate cells. Later on, as the differentiation progresses, the binding sites also become evident on the cell surface of pyriform cells. Once differentiated, the pattern of the distribution of DBA binding sites over the follicular epithelium does not change. By contrast, during the phase of intermediate and pyriform cell regression, DBA binding sites gradually decrease, so that the monolayered follicular epithelium of vitellogenic follicles, constituted only by small cells, shows no binding sites for DBA. It is noteworthy that binding sites for DBA are present on small cells located in contact with the oocyte membrane, but not on those located under the basal lamina or among pyriform cells, and therefore not engaged in the differentiation into pyriform cells. This finding demonstrates that, in squamates, the pattern of distribution of alpha-N-GalNAc containing glycoproteins significantly changes during previtellogenesis, and that these modifications are probably related to the differentiation of small stem cells into highly specialized pyriforms

Fine structure of Leydig and Sertoli cells in the testis of immature and mature spotted ray Torpedo marmorata

An ultrastructural investigation revealed the presence of true Leydig cells in the testis of sexually mature specimens of Torpedo marmorata. They showed the typical organization of steroid-hormone-producing cells, which, however, changed as spermatocysts approached maturity. In fact, they appeared as active cells among spermatocysts engaged in spermatogenesis, while in regions where spermiation occurred, they progressively regressed resuming the fibroblastic organization typically present in the testis of immature specimens. Such observations strongly suggest that these cells might be engaged in steroidogenesis and actively control spermatogenesis. Sertoli cells, too, appeared to play a role in spermatogenesis control, since, like Leydig cells, they showed the typical aspect of steroidogenic cells. In addition, the presence of gap junctions between Sertoli cells suggests that their activity might be coordinated. After sperm release, most Sertoli cells were modified and, finally, degenerated, but few of them changed into round cells (cytoplasts) or round cell remnants, which continued their steroidogenic activity within the spermatocyst and the genital duct lumen. From the present observations, it can be reasonably concluded that, in T. marmorata, spermatogenesis depends on both Leydig and Sertoli cells, and, as postulated by Callard (1991), in cartilaginous fish, the function of the Leydig cells as producers of steroids might be more recent and subsequent to that of Sertoli cells. In this regard, it is noteworthy that, in immature males, when Leydig cells showed a fibroblastic organization, Sertoli cells already displayed the typical organization of a steroidogenic cel