Provided for non-commercial research and education use. Not for reproduction, distribution or commercial use. Vol. 12 No. 1 (2019) Egyptian Academic Journal of Biological Sciences is the official English language journal of the Egyptian Society for Biological Sciences, Department of Entomology, Faculty of Sciences Ain Shams University. Entomology Journal publishes original research papers and reviews from any entomological discipline or from directly allied fields in ecology, behavioral biology, physiology, biochemistry, development, genetics, systematics, morphology, evolution, control of insects, arachnids, and general entomology. www.eajbs.eg.net ------------------------------------------------------------------------------------------------------ Citation: Egypt. Acad. J. Biolog. Sci. (A. Entomology) Vol. 12(1)pp: 9- 63 (2019) Egypt. Acad. J. Biolog. Sci., 12(1):9– 63 (2019) Egyptian Academic Journal of Biological Sciences A. Entomology ISSN 1687- 8809 www.eajbs.eg.net Characterization of Qualitative and Quantitative Haemogram Parameters in Insects: Current Concepts and Future Prospects. Karem Ghoneim Faculty of Science, Al-Azhar University, Cairo, Egypt Email: [email protected] or [email protected] __________________________________________________________ REVIEW INFO ABSTRACT Review History Since the circulating hemocytes are involved in the key Received:28/12/2018 physiological functions in insects, knowledge of these haemocytes Accepted:21/1/2019 is necessary to physiologists, toxicologists and biochemists. The ________________ present article was prepared to aim at updating the identification of Keywords: hemocyte types and discussing different terminological and haemolymph, technical difficulties. It focused, also, on most important heartbeat, quantitative parameters of haemogram and discussed various factors influencing their values. In this review, we described, also the origin hematology, of circulating hemocytes during embryonic and the postembryonic granulocyte, development as well as intensively reviewed the categorization of mitosis, oenocytoid, hemocyte types in several insect species of different orders. The osmosis, controversial terminology and technical difficulties of the hemocyte plasmatocyte, identification were discussed. It was emphasized that none of the prohemocyte, individual methods was satisfactory for all cell types within a given spherulocytes. insect but a combination of techniques should be used. The present chapter included only on the major quantitative parameters of haemogram, such as the total haemocyte count (THC), blood volume (BV) and mitotic index. It shed some light on the interrelationship between THC and BV. In addition, the endocrine control of THC and BV had been reported. The interrelationships between BV and osmotic pressure as well as between mitotic index and THC had been discussed. Heartbeat rate was reported to depend on different factors but the control mechanisms for the insect heart are not fully elucidated. List of Initials & Abbreviations: 20-hydroxyecdysone (20E), absolute haemocyte count (AHC), adipohemocytes (ADs), blood volume (BV), coagulocytes (CGs), corpora allata (CA), corpora cardiaca (CC), crystal cells (CRs), cystocytes (CCs), differential haemocyte count (DHC), fluorescence microscopy (FM), granulocytes (GRs), haemolymph volume (HV), juvenile hormones (JHs), lamellocytes (LMs), light microscopy (LM), mitotic index (MI), monoclonal antibodies (MAb), neurosecretory cells (NSCs), oenocytoids (OEs), plasmatocytes (PLs), podocytes (POs), prohemocytes (PRs), scanning electron microscopy (SEM), sessile cells (SCs), spherulocytes (SPs), thrombocytoids (TCs), total haemocyte count (THC), transmission electron microscopy (TEM), vermiform cells (VRs). ------------------------------------------------------------------------------------------------------ Citation: Egypt. Acad. J. Biolog. Sci. (A. Entomology) Vol. 12(1)pp: 9- 63 (2019) 10 Karem Ghoneim Contents: 1. Introduction ………………………………… 2. Categorization of circulating hemocyte types in insects …….. 2.1. Variation in number and types of circulating hemocytes…….. 2.2. Controversial terminology and technical difficulties of the hemocyte identification ……………… 3. Hemocyte population dynamics ………………… 3.1. Variation of total hemocyte population …………… 3.2. Factors influencing the total hemocyte population ………….. 3.3. Hemocyte population and endocrine control in insects ….. 4. Haemolymph volume as a quantitative haemogram parameter in insects …………. 4.1. Relationship between BV and hemocyte population ………….. 4.2. Factors influencing the variable BV value ……………. 4.3. An endocrine insight into the BV status ……………. 4.4. Interrelationship between BV and osmotic pressure ……… 5. Mitotic index as a parameter of haemogram profile in insects ….. 6. Is the heartbeat rate related to the hemocyte population or BV in insects? ………. 7. Summary points …………………….. 8. Conclusions and prospects for future work ………….. References ……………………….. 1. INTRODUCTION Insects have an open type of circulatory system. A pale colored fluid called 'haemolymph' (insect blood) circulates in the haemocoel (body cavity) bathing different organs and tissues (Jones, 1977; Wigglesworth, 1979; Gupta, 1979). Haemolymph, like the blood of higher animals, comprises two main components, the plasma and the corpuscles. The circulating cells in the insect haemolymph are called 'haemocytes'. They are morphologically distinct cell types and comparable to vertebrate leucocytes (Mead et al., 1986; Kerenhap et al., 2005; Pandey and Tiwari, 2012). In insects, there are several types of hemocytes. The most common types are prohaemocytes (PRs), plasmatocytes (PLs), granulocytes (GRs), spherulocytes (SPs), adiphohaemocytes (ADs), coagulocytes (CGs) and oenocytoids (OEs). It is important to emphasize that not all these hemocyte types exist in all insect species (Lavine and Strand, 2002; Meister and Lagueux, 2003; Lamprou et al., 2007; Wang et al., 2010; Manachini et al., 2011). However, their characteristic features are slightly different in various insect species (Gupta, 1979; Kanost et al., 2004; Meister, 2004; Ribeiro and Brehelin, 2006; Browne et al., 2013). Insect hemocytes are initially produced from the median mesoderm during embryogenesis (Ratcliffe et al., 1985; Tepass et al., 1994; Strand, 2008) and the majority of these cells circulate freely in haemolymph (circulating hemocytes), but a significant number, called 'sessile hemocytes', can be found associated with internal organs (fat body, gut, digestive system or dorsal tube) (Hillyer and Strand, 2014; Hillyer, 2016). On the other hand, origin of the hemocyte types seen during the postembryonic development is less clear. Maintenance of circulating hemocytes has been attributed to both the mitosis (cell division) of hemocytes already in circulation as well as to the release of hemocytes from hematopoietic organs (Feir, 1979; Ratcliffe et al., 1985; Gillespie et al., 1997; Lavine and Strand, 2002; Holz et al., 2003; Tan et al., 2013; Grigorian and Hartenstein, 2013). These organs provide the correct cellular and molecular environment for the control of cell proliferation and Characterization of Qualitative and Quantitative Haemogram Parameters in Insects 11 differentiation (Koch and Radtke, 2007; Martinez-Agosto et al., 2007). Also, different hemocyte types are thought to be produced via the differentiation of circulating prohaemocytes and via linear transition of prohaemocytes to plasmatocytes and subsequent differentiation into other hemocyte types (Beaulaton, 1979; Yamashita and Iwabuchi, 2001). For last few decades, the worldwide research on insect circulating haemocytes has received much attention (Wigglesworth, 1959; Jones, 1962; Gupta, 1979; Hall, 1983; Lavine and Strand, 2002; Ribeiro and Brehelin, 2006; Suhail et al., 2007; Strand, 2008; Shaurub, 2012; Soares et al., 2013; Siddiqui and Al-Khalifa, 2014; Kwon et al., 2014; Ghoneim et al., 2015a,b, 2017) because these cells perform different physiological functions, such as cell development and differentiation; metabolic processes; endocrine regulation; reproductive potential; transport of essential biological materials between cells, tissues and organs; coagulation to prevent loss of blood; preservation of an insect homeostasis; defense reactions against parasites and pathogens invading the insect body cavity (phagocytosis, encapsulation and nodulation); detoxification of metabolites and other foreign bodies, as well as synthesis, storage, distribution of nutritive materials and hormones to various tissues throughout the insect body and wound healing (for some details, see: Garcia and Rosales, 2002; Lavine and Strand, 2002; Ceraul et al., 2003; Zhou et al., 2004; Ling et al., 2005; Figueiredo et al., 2006; Ribeiro and Brehelin, 2006; Wood and Jacinto, 2007; Singh et al., 2008; Strand, 2008; Glenn et al., 2010; Pandey et al., 2010, 2012; Siddiqui and Al-Khalifa, 2012a; Chavan et al., 2017). In addition to these functions, insect hemocytes are responsible for clearing apoptotic cells during development (Kurtz, 2002) and they are regarded as an excellent model system for the study of cell communication (Manogem et al., 2015). However, some of the important reviews dealing with various aspects of hemocytes (viz., categories, function, cellular responses, etc.) are those of Rizki (1962), Rowley and Ratcliffe (1981), Arnold (1982), Gupta (1985), Brehelin and Zachary (1986), Lackie (1988), Ribeiro and Brehelin (2006), Izzetoğlu and Karaçali, (2010), Pandey