A Comparative Study Of The Ultrastructure Of Spermatozoao Of Four Species Of Toad-headed Lizards, Phrynocephalus Immaculatus, Phrynocephalus Frontalis, Phrynocephalus Versicolor And Phrynocephalus Vlangalii

We studied the ultrastructure of epididymal spermatozoa of four species oftoad-headed lizards, Phrynocephalus immaculatus, P. frontalis, P. versicolor and P.vlangalii. Spermatozoa of these four species exhibit spermatozal synapomorphies ofsquamate repriles in the following features: an acrosomal vescile, a subacrosomalcone, a prenuclear perforatorium, a nuclear rostrum,absence of a endonuclear canal,the fibrous sheath into the midpiece, the peripheral dense fibers adjacent to doublets 3and 8 presence a double structure nearer the annulated fibrous sheath.The major differences in the ultrastructure of spermatozoa between the fourspecies of toad-headed lizards include: the sperm of P. immaculatus and P. vlangaliiare characterized by an epinuclear lucent zone, 10 mitochondria in the transversesection. On the contrary, the sperm of the other two lacks an epinuclear lucent zone,and is characterized by 11 mitochondria in the transverse section. In the longitudinalsection, the dense bodies are columnar in P. vlangalii, but ovoid in the other threespecies. The ultrastructural traits of spermatozoa that are common among the fourspecies of toad-headed lizards include: a depressed acrosome at the anterior portion;an acrosomal vescile divided into cortex and medulla; an elongated nucleus; absenceof a endonuclear cannal; rounded nuclear shoulders; a coned nuclear fossa; a bilateralstratified laminar structure within neck region; a long axis of the proximal centriole almost vertical to that of the distal centriole; nine peripheral dense fibres connectinginward with the corresponding 9 triplets of the distal centriole and backward with thedoublets of the axoneme; central fibres connecting with the two central singlets; ashort midpiece; mitochondria with linear cristae; each intermitochondrial ringstructure consisting of the incomplete ring of irregularly ovoid dense bodies; a fibroussheath into the midpiece; presence of an annulus; the arrangement pattern of the ringstructure and mitochondria in rs1/mi1, rs2/mi2,rs3/mi3,rs4/mi4 and rs5/mi5; athin granular zone of cytoplasm at the anterior portion of the principal piece;theaxoneme complex having an usual 9+2 pattern. Evidence of spermatozoalautapomorphies is not found in the family Agamidae.However, lizards of different taxa differ, in various degrees, in such spermultrastructure traits as acrosome vesicle, subacrosomal space, epinuclear lucent zone,nuclear shoulder, mitochondria, arrangement and number of mitochondria and densebodies, ring structure. These differences suggest that sperm morphology providesadditional information by which one may use to study phylogeny of lizards.