Dynamics of oogenesis in ghost shrimp Callichirus major (Crustacea: Axiidea): a morphofunctional and histochemical study.

Callichirus major, popularly known as ghost shrimp, is a species of great importance in the fishing industry, because of its use as live bait. This study aimed to describe the different stages of the developing ovaries in C. major. Shrimps were collected along the Corujão beach, Piuma, Brazil (20°50'41.6"S 40°44'15.7"W), and the gonads were dissected for histological and histochemical analysis. The ovary consists of two elongated filaments covered by a connective tissue that divides the organ into lobules, where somatic and germ cells are found. It was possible to classify five types of germ cells: Oogonia (Oog), previtellogenic oocyte (Oc1), early vitellogenic oocyte (Oc2), late vitellogenic oocyte (Oc3) and mature oocyte (Oc4) based on their vitellogenic stage, cytoplasmic, nuclear and morphometric characteristics. The histochemical analysis demonstrated an intense reaction for proteins and polysaccharides in peripheral cytoplasm of Oc3 comparing to others cell types. According to size, volume, color intensity and distribution of oocyte types the gonads were classified into: immature, developing, developed and spent, being in females at this last stage, observed empty follicles and oocytes in reabsorption process. During oogenesis was observed a gradual increase in cytoplasmic acidophilia due to accumulation of yolk granules and the intense histochemical reaction in periphery of Oc3, which indicate the beginning of an extravitellogenic source of nutrients. Based on the microscopic analysis of the vitellogenesis, shrimp C. major showed the initial short phase of oocyte growth following with a fast vitellogenic cycle.

Histological and histochemical features of the oogenesis in the simultaneous protandric hermaphrodite shrimp Exhippolysmata oplophoroides (Decapoda: Caridea).

This study analyzes the dynamics of the vitellogenesis process in the simultaneous protandric hermaphrodite shrimp Exhippolysmata oplophoroides, based on light microscopic observations. The ovotestes of the shrimps at the different gonadal development stages were removed, fixed and submitted an usual histological procedure (HE) and histochemical techniques (Bromophenol Blue, PAS/Alcian Blue, and Von Kossa tests). The germinative cells were classified into oogonias, and oocytes in stages I-IV based on the following features: cell size, cytoplasm appearance, presence of yolk granules, lipid droplets, chorion, and chromatin patterns. In the male initial phase of the gonadal development, the ovotestes present mainly oogonia and oocytes I and II while in the functional hermaphrodite phase, oocytes III and IV predominate in the peripheral zone of the gonads. Oocytes with an atypical appearance of the cellular components indicative of reabsorption were also observed. This study showed an increasing accumulation of proteins, carbohydrates and lipids occurring as the germ cells develop, being the yolk elements deposited in a sequence, in which proteins and carbohydrates are the first to appear both by an endogenous as well as also by an exogenous origin. The presence of calcium was detected mainly in oocytes I, II and inside those in reabsorption, being posteriorly mobilized to chorion constitution and/or to hemolymph due to its role during molting. Although the similarity of the germ cells shape among the crustaceans, this first histochemical characterization of E. oplophoproides ovary increases the comprehension of oogenesis in a caridean simultaneous protandric hermaphrodite species.