Ultra-Differentiation of Sperm Tail of Lesser Egyptian Jerboa, Jaculus Jaculus (Family: Dipodidae)

Journal of Advanced Laboratory Research in Biology E-ISSN: 0976-7614 Volume 7, Issue 1, 2016 PP 27-35 https://e-journal.sospublication.co.in Research Article Ultra-differentiation of Sperm Tail of Lesser Egyptian Jerboa, Jaculus jaculus (Family: Dipodidae) Osama M. Sarhan1,3* and Hany A. Hefny2,4 1Department of Zoology, Faculty of Science, Fayoum University, Egypt. 2Department of Zoology, Faculty of Science, Suez Canal University, Egypt. 3Department of Biology, Faculty of Applied Science, Umm Al-Qura University, KSA. 4Department of Biology, University College, Um Al Qura University Al-Jomoum KSA. Abstract: In the present study, events of sperm tail differentiation in Lesser Egyptian Jerboa, Jaculus jaculus were studied for the first time. Generally, stages of sperm tail differentiation are more or less similar to that described by other studies in other rodents. In the present species, special structures were observed. These structures include, first: the formation of a hollow large unit of microtubules that appears to surround the nuclear envelope at its equatorial plane. The manchette microtubules (MMs) are re-oriented toward the longitudinal direction and attached along hollow large unit of microtubules. Second, the formation of perinuclear space filled with an electron-translucent substance surrounds the posterior third of the developing nucleus. Third, the nuclear fossa and the connecting piece were inserted in the ventrodorsal region of the nucleus. Fourth, the fibrous sheath (FS) is formed of dextral spiral fibrous ribs. Finally, the sperm tail of the present species has a single outer FS, however, other rodents, having additional inner fibrous units, between the outer FS and the inner developing axoneme. Keywords: Ultrastructure, Sperm tail, Lesser Egyptian Jerboa, Jaculus jaculus, Rodents, Mammals. 1. Introduction Spermiogenesis involves highly regulated developmental and morphological stages during which Although Lesser Egyptian Jerboa, J. jaculus has a quiescent, inactive spermatids gain new movable wide geographical range in the middle-east with diverse shapes with highly specialized heads, necks, middle habitats, including coastal sand dunes, desert, semi- pieces, in addition, principal and end pieces of the tail desert and rocky regions, it is recorded in the red list of regions [3] with disposal of excess cytoplasmic threatened species [1]. In Egyptian mammals, components [4]. Mammalian sperm head and tail insufficient data have published to explain the stages of differentiation has been studied in the platypus, spermiogenesis in the mammalian fauna of Egypt. Ornithorhynchus anatinus [5], shrews [6-8], bats, Shahin and Ibraheem [2] described two morphs of Rhinopoma kinneari and Myotis macrodactylus [9-10], spermatozoa in Egyptian dipodids. The sperm head has marsupials [11,12], cats [13], as well as in primates, long paddle-shaped of pear-short heads with long or such as Callithrix jacchus and Rhesus monkey [14,16], short tails, however, their connecting pieces may be and man [17-19]. However, spermiogenesis of rodents inserted centrally or attaches mid basally to the lower [20-22] was also studied in mice [23-25], rat [26,27], concavity at the base of the sperm head. However, the and Guinea pig [28,29]. stages of spermiogenesis of the Egyptian jerboas Stages of sperm tail differentiation include the including present species was not investigated in formation of specific structures in the neck's connecting details. Furthermore, Sarhan [3] studied spermiogenesis piece, formation of axial filament, MS and FS in the of Egyptian fat-tailed gerbil, Pachyuromys duprasi. He middle piece that terminates at the annulus, in addition, described very long acrosomal segment that capping the study the fine structure of the principal and a terminal entire nucleus, with unique structures including special end piece of the tail [30-36]. These published data of mitochondrial sheath (MS), two FS and fin-like mammalian spermiogenesis described numerous fine structure supported by dorsal and ventral pairs of structures which are specific to different species, but fibrous masses that disappear in the same structure of none, dealing with Lesser Egyptian Jerboa. Thus, the the end piece. present study aimed to discover the specific ultra- *Corresponding author: E-mail: [email protected]. Ultra-differentiation of Sperm Tail of Jaculus jaculus Sarhan and Hefny structures of sperm tail differentiation of the present "MMs" (Figs. 3-9). Finally, unique FS and axial threatened species, J. jaculus. filament are formed (Figs. 12-19). Thus, the developing spermatid consists of a head with an elongated nucleus 2. Material and Methods capped with different adjacent, abutted segments of acrosome connecting piece and middle piece (Fig. 6 & 2.1. Animals 9). Ten adult males of Lesser Egyptian Jerboa, J. With more detail, Figures 10-12 show specific jaculus were collected, during the period of their sexual structures in the neck and middle piece of the sperm. In activity between April and May, from the Marsa the neck region, the connecting piece of the tail shows Matrouh region, at the northwest coast of Egypt. the insertion of proximal and distal centrioles in the NF, which situated at the ventrodorsal side of the nucleus. 2.2. Dissection and preparation of tissues Also, the neck region contains centrioles, chromatoid Animals were dissected, their testes extracted, bodies (CB), skeleton of the connecting piece, which, immediately washed in cold cacodylate buffer, cut into represented by longitudinal bundles of MMs (Figs. 3, 6 thin slices and fixed for 6h using 2.5% glutaraldehyde & 9). The mechanism of microtubules re-orientation in 0.1mol cacodylate buffer adjusted at 7.2 pH. One starts at equatorial level of the nuclear envelope, hour later, selected sliced were cut into 1mm units for whereas, some microtubules unite together to form good fixation, washed in fresh cacodylate buffer to large hollow microtubule unit (MtU) running in a remove residual tissues and transferred into small circular pathway (Figs. 6 & 8). At this point, the brown bottles filled with fresh 2.5% cold acrosomal cap stop, however, other longitudinal glutaraldehyde to complete fixation in the refrigerator. bundles of microtubules (Figs. 2-4) attach to the After fixation, the small specimens washed in circular MtU (Figs. 6-9). MMs draw the cell membrane cacodylate buffer and post-fixed for 3 hours by adding to surround both acrosomal cap and nuclear envelope, 1% cold osmium tetroxide (OsO4) dissolved in in the same time, forcing other cytoplasmic components cacodylate buffer and re-washed in cacodylate buffer. towards connecting piece of the tail (Figs. 4-9). Also, a Tissues were dehydrated in ascending grades of new cavity, filled with translucent material, appears to ethanol, cleared in propylene oxide and embedded in surround the posterior nuclear protrusion as a resistance EponAraldite mixture. Semi-thin sections were cut at structure, which may be protects the chromatin during 1µm thick using glass knives, stained with toluidine the condensation period. Figs. from 4 to 9 showed blue and examined under research light microscope posterior perinuclear space, which gradually increases (Axioskop 2 Plus, Zeiss, Germany) to select the most to surround the posterior nuclear protrusion (PN). It is active sites containing different stages of worth to mention that this space is located between spermiogenesis. Ultra-thin sections were cut, stained anterior (ANS) and posterior nuclear shelves (PNS) as with 1.5% aqueous uranyl acetate followed by shown in Figure 9. Reynold's lead citrate and studied under a Jeol "JEM- The middle piece involves a growing axoneme 1200 EXII" operating at 60-70kv. Selected figures were (AX) surrounded by ribs of a unique fibrous sheath taken for description. (RFS). The outstanding rear forms of FS, which is represented by contiguous fibrous ribs that arranged in 3. Results a dextral spiral (Fig. 11). Figures 13 and 14 show mitochondria surround the axial filament in the Early spermatids of Lesser Egyptian Jerboa, J. transverse sections in the different parts of the middle jaculus have spherical nucleus with fine chromatin piece including the initial (IMP), posterior (PMP) and granules and their cytoplasm showed few mitochondria. terminal (TMP) portions. The terminal end of the In addition, numerous solitary microtubules arranged middle piece is restricted by an annulus (AN) formed of under the plasma membrane, and around the nuclear a poor and thin discoid fibrous plate (Fig. 15) that envelope that oriented in circular patterns (Fig. 1). allows the growing axoneme and the surrounding FS to Briefly, the events of the present sperm tail protrude and extends posteriorly, forming a long differentiation include nuclear elongation, that principal piece and a thick short end piece. In both protrudes into anterior and posterior directions (PN) regions, a relatively thick FS surrounds an axial (Figs. 2, 3), formation of a basal plate (BP), and nuclear filament. Figures 16-19 show that the ultra-structures of fossa (NF), at its posterior ventrodorsal side (Figs. 2, 3). the principal and the end piece of the sperm tail are The situation of this fossa shows that the connecting more or less similar in its structure and diameter of the piece of the tail is attached to the sperm head at this FS. In the principal piece, the FS has homogeneous unexpected situation (Figs. 2, 3). Moreover, the fibrous ribs, with two large ribs, situated at its lateral proximal (PC) and distal (DC) centrioles are fitted in or sides (LFR) (Fig. 16). The transverse sections showed nearby the nuclear fossa (NF) (Figs. 2, 3, 5), and the the structure of FS and axial filament, narrowing cytoplasmic components are aggregated at the posterior towards the end of the tail with thinner fibrous ribs and end of the sperm head, namely connecting piece (CP) constant radius of the axial filament (Figs. 17-19). which mainly supported by longitudinal bundles of J. Adv. Lab. Res. Biol. 28 Ultra-differentiation of Sperm Tail of Jaculus jaculus Sarhan and Hefny Fig. 1. Electron Micrographs showed two early spermatids.

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