From a structural study of the midgut of Centropages typicus, three main zones presenting different cellular associations may be defined. The ultrastructural study carried out allows us to distinguish several cell types. The four principal cell categories (E, R, F and B) show a more or less marked resemblance with those identified in the Malacostraceans, especially in the hepatopancreas of Decapods. The three types R, F and B, which are subdivided according to their localization (R and R') or their developing stages (F1, F2; B1 to B5), are recognized by the following characteristics: R-cells with smooth endoplasmic reticulum and high microvilli (zones I and III); F-cells with rough endoplasmic reticulum and short or spherical microvilli (zones I and II); B-cells with a large vacuolar apparatus made up of lysosome-like dense bodies associated with vacuoles originating from pinocytosis (zone II). From the comparisons of morphological, ultrastructural and histochemical results concerning Centropages typicus with author's data, we propose and discuss these functions for the three principal cell types: synthesis and secretion of pre-digestive enzymes (F1 and F2-cells); enzyme synthesis, intracellular digestion and extrusion (B1 to B5-cells); absorption (R and R'-cells).

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The genital area in Hemidiaptomus ingens provinciae and Mixodiaptomus kupelwieseri is made up of several external and internal solidary cuticular components, which connect the genital ducts with the outside. Its outer part, which is located on the ventral side of the genital segment, is delimited by an ovoid cuticular fold and by two swelling processes, one dorsal and the other ventral. The center is occupied by two operculums, which are separated from a median wall by two crescent-shaped genital apertures. The inner part of the area essentially includes two U-shaped ducts by which the oviducts are connected to the genital apertures. During egg laying, to allow oocytes and oviductal secretions to be carried out through the genital apertures, the ducts take a more or less circular section, owing to the contraction of muscles attached to their wall. At this stage, the genital area is entirely masked by a temporary external seminal receptacle. The genital area assumes a double function in reproduction: first, in stocking spermatozoa in the seminal receptacle, and second, in allowing oocyte laying and fecondation as they are pushed into the ovisac.

Two groups of external excretory pores associated with glandular units (AU and LPU) were observed on the labrum, one pair laterally and three pairs posteriorly. Each external pore leads to an underlying conical, flask-shaped epidermal chamber. The wide base of this chamber is perforated by an internal pore that delivers secretions from the excretory duct of a glandular unit. The chambers serve to protect the internal pores from turbulence in the outside environment. Expulsion of secretions from the chambers is probably brought about by contraction of labral striated muscles, which synchronizes opening of the AU and LPU pores. A complex funnel-shaped structure forms the internal end of the excretory duct between each chamber and the corresponding pole of accumulation for the secretory product of a glandular unit. This structure, composed of an epidermal syncytium lined by a sleeve of several aligned auxiliary cells, probably ensures a tight connection between the epidermal chamber and the syncytium. The dorsalmost glandular units (LDU) have no pores in the vicinity of their poles of accumulation. Instead they secrete through cuticular ducts delimited by aligned auxiliary cells. External pores for these canals have not yet been located. The secretions of lateral pores may be mucopolysaccharides that play an essential role in agglutination of food particles soon after capture, while the secretions of posterior pores may contain glycoproteins that mix with food only after ingestion into the buccal cavity and probably start the process of digestion.