External Morphology and Ultrastructure of Tegumental Glands of Aegla platensis (Crustacea, Anomura, Aeglidae) Pleopods: Might They Play A Role in Egg Attachment?

Abstract

Egg incubation on the female abdomen is the parental care behavior observed in aeglids, in which eggs are kept adhered to maternal pleopods and maintained, cleaned and aerated. In A. platensis, egg attachment occurs with the aid of pleopodal setae, which are twisted around their axis in the distal region, forming the funiculus, and pleopodal glands, which are responsible for the production of the adhesive substance that seems to be involved in egg fixation to pleopodal setae. Those glands are acini formed by secretory cells arranged concentrically around a central duct, giving them a rosette appearance. Two types of secretory cells were observed, those that produce electron-lucid vesicles and those having electron-dense ones. Both kinds of vesicles are released in a duct whose opening pore is located on the pleopodal surface and constitute the adhesive substance that coats eggs and pleopodal setae, ensuring egg fixation to the female body and maternal care maintenance. This study investigates the internal and external morphology of Aegla platensis pleopods, to understand the egg attachment process and identify the structures involved in this phenomenon. Three microscopy techniques are used: scanning electron microscopy (SEM), transmission electron microscopy (TEM), and optical microscopy (OM).

Scanning electron microscopy of vitellogenic oocytes and spawned eggs of the portunid crab Charybdis hellerii (Crustacea-Brachyura) (Milne Edwards, 1867)

“…[ 22 ] Similarly, In Aegla platensis , the funiculus is formed by addition of an adhesive substance to pleopodal setae. [ 46 ] In Austropotamobius pallipes , the funiculus has a dual origin long setae and egg outer layer. [ 49 ] In the present investigation, it was clearly observed that the funiculus is derived from the outermost envelope of the egg.…”