Morphology and ultrastructure of the somatic cells in Astacus leptodactylus ovary

Abstract

We defined the somatic environment in which female germinal cells develop, and performed ultrastructural analyses of various somatic cell types, with particular reference to muscle cells and follicle cells, that reside within the ovary at different stages of oogenesis. Our findings show that ovarian wall of the crayfish is composed of long muscle cells, blood cells, blood vessels and hemal sinuses. The follicle and germinal cells lie within a common compartment of ovarian follicles that is defined by a continuous basal matrix. The follicle cells form branching cords and migrate to surround the developing oocytes. A thick basal matrix separates the ovarian interstitium from ovarian follicles compartment. Transmission electron microscopy shows that inner layer of basal matrix invaginates deeply into the ovarian compartment. Our results suggest that before being surrounded by follicle cells to form follicles, oogonia and early previtellogenic oocytes reside within a niche surrounded by a basal matrix that separates them from ovarian interstitium. We found coated pits and coated vesicles in the cortical cytoplasm of previtellogenic and vitellogenic oocytes, suggesting the receptor mediated endocytosis for transfer of material from the outside of the oocytes, via follicle cells. The interstitial compartment between the inner muscular layer of the ovarian wall and the basal matrix of the ovarian follicle compartment contains muscle cells, hemal sinuses, blood vessels and blood cells. Granular hemocytes, within and outside the vessels, were the most abundant cell population in the ovarian interstitium of crayfish after spawning and in the immature ovary.

Effect of Sublethal Nickel Chloride Exposure on Crayfish, Astacus leptodactylus Ovary: An Ultrastructural, Autometallographic, and Electrophoretic Analyses

“…The interstitial compartment situated between the inner muscular layer of ovarian wall and the basal matrix of ovarian follicle compartment contains muscle cells, hemal sinuses, blood vessels, and blood cells. Ultrastructure of the A. leptodactylus ovary has been described recently by our group (Petrescu et al, 2016).…”

“…Intracisternal granules are considered to be the sites of the endogenous precursors of proteinaceous yolk (Beams & Kessel, 1963). Previous studies have shown the presence of coated vesicles in previtellogenic oocytes of A. leptodactylus , suggesting that, before the onset of vitellogenesis, follicle cells can deliver other substance into oocytes by receptor-mediated endocytosis (Petrescu et al, 2016). In light of the findings in our study, we can therefore reasonably speculate that nickel may bind to various ligands in hemolymph or follicle cells and in this form is incorporated through endocytosis in the yolk.

Figure 6 Autometallographic staining of oocytes from nickel-exposed Astacus leptodactylus .

…”

Scanning Electron Microscopy of Vitellogenic Oocytes and Spawned Eggs of the Portunid Crab Charybdis hellerii (Crustacea-Brachyura) (Milne Edwards, 1867)

“…Similarly, the cortical cytoplasm of previtellogenic and vitellogenic oocytes of Astacus leptodactylus were characterized by the presence of coated vesicles. [ 39 ] The authors suggested that before the onset of vitellogenesis, follicle cells can deliver other substances into oocytes by receptor-mediated endocytosis. [ 39 ]…”

“…[ 39 ] The authors suggested that before the onset of vitellogenesis, follicle cells can deliver other substances into oocytes by receptor-mediated endocytosis. [ 39 ]…”