Ovarian cycle and scanning electron micrographs of the spawned egg of female mantis shrimp Oratosquilla massavensis (Alexandria, Egypt)

Mantis shrimp Oratosquilla massevensis is an abundant marine crustacean in Egypt. It is common among the most important predators in many shallow, tropical and subtropical marine habitats. It is poorly understood as many species spend most of their life tucked away in burrows and holes. The objective of this study is to provide information on the histological characteristics of the ovary of female mantis shrimp O. massevensis and the morphology of the spawned egg, using scanning electron microscope. The ovaries showed a pronounced macroscopic differentiation in size and color with the maturation of the ovary, in six developmental stages namely: immature stage, previtellogenesis, primary vitellogenesis, secondary vitellogenesis, maturation and spent stage. Staining affinities of different structural components, size of different oocytes and nuclear sizes, as well as the follicular cells and their association with oocytes were used to differentiate between different oocyte developmental stages. Scanning electron micrographs of the spawned egg of O. massavensis revealed spherical forms of the egg with well noticed stalk or funiculus. The chorion is ornamented as a wrinkled layer with different textures. Two different yolky materials or matrices were observed, the first one constitutes a conical shaped hard matrix with glassy appearance, while the second one appears spongy with somewhat soft appearance.