Mitosis and cell death in the optic lobes of workers, queens and drones of the honey bee (Apis mellifera) during metamorphosis.

Colonies of the honey bee, Apis mellifera, consist of males and two female castes: workers and queens. The castes and males from A. mellifera have a distinct morphology, physiology and behaviour that correlate with their roles in the society and are characterized by some brain polymorphisms. Compound eyes are one of the characteristics that differ among the castes and sexes. A. mellifera is a holometabolous insect; therefore, the development of adult organs during metamorphosis, which will produce these differences, requires the precise coordination of three main programmed cellular processes: proliferation, differentiation and death. These processes take place simultaneously during pupation. Our purpose was to investigate cell division and death in the optic lobes (OL) of workers, queens and males during pupation to identify how the differences in the compound eyes in adults of these classes are achieved. The results showed that OL differentiation follows a similar pattern in the three classes of individuals studied, without structural differences in their development. The main non-structural differences involve cell division, mortality rates and timing. The results suggest a modelling of the brain during differentiation, which contributes to the specifi c functions of each individual class.

Effect of juvenile hormone III on the ultrastructure of the corpora allata in Melipona quadrifasciata (Hymenoptera,. Apidae, Meliponýný)

Changes in hormonal levels can produce alternative phenotypes. Juvenile hormone III plays an importantrole in the regulation of metamorphosis, caste determination and age in bees. In this work, we examined theultrastructure of corpora allata cells from stingless bees (Melipona quadrifasciata) treated with juvenilehormone during development. The corpora allata cells of M. quadrifasciata queens showed greater activitythan those of workers. The topical application of juvenile hormone III altered the cellular ultrastructureand either delayed development (as shown by fewer mitochondria and greater chromatin condensation) orenhanced development (looser chromatin and numerous mitochondria) when compared to untreated (control)bees. Our results show that corpora allata cells differ in their ultrastructural characteristics and that thecessation of juvenile hormone production by these cells in M. quadrifasciata is not synchronous.

Histological ultrastructural aspects fat body virgin physogastric queens Melipona quadrifasciata anthidioides lepeletier, 1836 (HYMENOPTERA, APIDAE, MELIPONINI)

Variations in the morphology and biochemical content of insect fat body have been associated withmetabolic activity and the reproductive cycle (synthesis of vitellogenin). In social insects such as bees,the functional traits of fat body also differ between workers and queens. In this work, we used light andtransmission electron microscopy to examine the morphological features of fat body trophocytes of virginand physogastric mated queens of the stingless bee Melipona quadriafasciata anthidioides before and duringvitellogenesis. Virgin queens had few, small fat body cells in which lipid deposits predominate, and showedno evidence of biosynthetic activity or the uptake of exogenous substances. In contrast, the fat body cells ofphysogastric queens were almost completely devoid of lipids, exhibit a well-developed rough endoplasmicreticulum with an obvious intraluminal product, and contained Golgi stacks that release numerous vesicles.These ultrastructural findings were suggestive of proteosynthesis. However, there was no evidence for theaccumulation of synthesized material in the form of secretory granules. We conclude that the trophocytes ofvirgin and physogastric queens differ basically in their switch from a storage role in the former to a syntheticrole in the latter. In addition, the high level of vitellogenesis seen in egg-laying queens suggests that themain material synthesized is vitellogenin.

Macroscopic aspects and scanning electron microscopy of the ovaries of the Spiny Lobsters Panulirus (Crustacea: Decapoda)

In spite of its importance as a major fishing resource in Northeastern Brazil, little is known regardingthe reproductive biology of the spiny lobster. The present study describes the macroscopic morphologyand scanning electron microscopic (SEM) structure of the ovaries of the species Panulirus argus, P.laevicauda and P. echinatus. The morphological study included the parameters developmental stage, colorand surface texture. With samples fixed in Bouin and Karnovsky solution, SEM analyses identified fourdistinct stages (I. immature, II. prematuration, III. mature, IV. spawning/resorption) as well as changesin the organization of the somatic (fibrous tissue) and germinative (oocytes) components at each stage. AtStage I, ovaries consist of nodes or cysts and are lined with thick fibrous components which tend to distendtoward Stage III. The oocytes are rounded and the nucleus/cytoplasm ratio decreases as the cells growlarger and move towards the periphery. As the first SEM-aided description of Panulirus ovaries, the presentstudy represents a contribution to our understanding of the tridimensional organization of the ovariancomponents at different stages of maturation and sheds new light on the changes which occur during thematuration process of spiny lobsters.

Ultrastructure of the spermathecal gland of Melipona bicolor lep. (Hymenoptera, Apinae, Meliponini)

The ultrastructural features of the spermathecal gland of Melipona bicolor, a stingless bee, are described. The gland in this species is very small, but the organization of the cells and theis ultrastructural features are very similar to those of Apis mellifera. The gland consist of two short tubular diverticuli connected directly to the spermatheca. The diverticuli are constituted by class III glandular cells. The only difference between the glands of virgin and mated queens is the presence of glycogen deposits in virgins, probably remmants of energetic reserves frequently present in young tissues. The physiological role of the secretion of this organ is not known since its lipid morphological aspect, does not seem support a nutritional function to the sperm cells.