Electron microscope study of spermiogenesis in<i>Caiman crocodylus</i>L.

Saita, A.; Comazzi, M.; Perrotta, E.

doi:10.1080/11250008709355602

Cited by 22 publications

(56 citation statements)

References 10 publications

(4 reference statements)

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“…The observed projections closely resemble structures previously reported in various lizard species [37-42] as well as in the Caiman ( Caiman crocodiles ) [43] and Nile crocodile ( Crocodylus niloticus ; personal observations). However, no morphological data other than the length of the “filaments” in the Caiman crocodile [43] have been presented. Based on TEM observations, the present study revealed that the projections were short, evenly spaced, peg- or finger-like extensions closely associated with the outer (cytoplasmic) face of the nuclear membrane.…”

Section: Resultssupporting

confidence: 85%

“…The corresponding zone of cytoplasm of all other non-passerine species studied is occupied only by a layer of fine flocculant material [20,21,24,26-36]. The observed projections closely resemble structures previously reported in various lizard species [37-42] as well as in the Caiman ( Caiman crocodiles ) [43] and Nile crocodile ( Crocodylus niloticus ; personal observations). However, no morphological data other than the length of the “filaments” in the Caiman crocodile [43] have been presented.…”

Section: Resultssupporting

confidence: 71%

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A novel transient structure with phylogenetic implications found in ratite spermatids

Plessis

Soley

2013

BMC Evol Biol

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BackgroundA novel transient structure was observed in the spermatids of three ratite species using transmission electron microscopy.ResultsThe structure first appeared at the circular manchette stage of sperm development, was most prominent during the longitudinal manchette phase and disappeared abruptly prior to spermiation. It was composed of regularly-spaced finger-like projections which were closely associated with the outer nuclear membrane, giving the nucleus a cogwheel-like appearance. The projections were approximately 30 nm long and 14 nm wide. Although a similar structure has been described in certain lizard and crocodile species, this is the first report of a similar structure in the developing spermatids of birds.ConclusionsThe potential value of non-traditional characters, such as spermiogenesis and sperm ultrastructure, as phylogenetic markers has recently been advocated. The morphologically unique structure found in ratite spermatids provides additional evidence of a possible phylogenetic link between the reptiles and birds. It also endorses the basal positioning of the ratites as a monophyletic group within the avian phylogenetic tree.

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Section: Resultssupporting

confidence: 85%

Section: Resultssupporting

confidence: 71%

A novel transient structure with phylogenetic implications found in ratite spermatids

Plessis

Soley

2013

BMC Evol Biol

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“…23, turtle). The number of mitochondria appears from the few studies done to date to be fairly consistent along the length of the midpiece in turtles, 60,61 crocodilians, 62,63 and the tuatara 53 Figure 15. A sagittal section through the head and proximal flagellum of a spermatozoon from the lumen of a seminiferous tubule of the American Alligator (Alligator mississippiensis).…”

Section: Discussionmentioning

confidence: 80%

“…In Lepidosauria (snakes, lizards and tuataras), only 8 studies have entire ultrastructural descriptions of spermiogenesis: the skink, Chalcides ocellatus; 52 the tuatara, Sphenodon punctatus; 53 59 Even less information on spermiogenesis exists in turtles and crocodilians. Four studies that provide entire ultrastructure details of spermatid development occur in the turtles Trachemys scripta 60 and Pelodiscus sinensis, 61 and in the crocodilians Caiman crocodylus 62 and Alligator mississippiensis. 63 The round spermatids (Fig.…”

Section: Germ Cell Cycle and Germ Cell Morphologies During Spermatogementioning

confidence: 99%

Reptilian spermatogenesis

Gribbins¹

2011

Spermatogenesis

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Until recently, the histology and ultrastructural events of spermatogenesis in reptiles were relatively unknown. Most of the available morphological information focuses on specific stages of spermatogenesis, spermiogenesis, and/or of the mature spermatozoa. No study to date has provided complete ultrastructural information on the early events of spermatogenesis, proliferation and meiosis in class Reptilia. Furthermore, no comprehensive data set exists that describes the ultrastructure of the entire ontogenic progression of germ cells through the phases of reptilian spermatogenesis (mitosis, meiosis and spermiogenesis). The purpose of this review is to provide an ultrastructural and histological atlas of spermatogenesis in reptiles. The morphological details provided here are the first of their kind and can hopefully provide histological information on spermatogenesis that can be compared to that already known for anamniotes (fish and amphibians), birds and mammals. The data supplied in this review will provide a basic model that can be utilized for the study of sperm development in other reptiles. The use of such an atlas will hopefully stimulate more interest in collecting histological and ultrastructural data sets on spermatogenesis that may play important roles in future nontraditional phylogenetic analyses and histopathological studies in reptiles.

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“…In the columbiforms Ocyphaps lophotes and Geopelia striata, even a perforatorium is absent (Jamieson, unpub.). The psittaciform restriction of the endonuclear canal, housing the perforatorium, to the anterior region of the nucleus is here recognized as an apomorphic condition shared with other nonpasserines (galliforms and the whitenaped crane, Phillips et al, 1987) and crocodilians (Saita et al, 1987).…”

Section: Midpiece Centrioles and Axonernementioning

confidence: 97%

Spermatozoal ultrastructure in three species of parrots (Aves, psittaciformes) and its phylogenetic implications

1995

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(1) These features are tetrapod symplesiomorphies, (2) is an amniote synapomorphy; the fibers differ from those of reptiles in being uniform in size, (3) loss of the fibrous sheath is an apomorphy known elsewhere only in columbiforms, (4) are apomorphies relative to basal aminiotes (Chelonia, Sphenodon, and Crocodilia), (5) is an apomorphic condition shared with other nonpasserines (galliforms and the white-naped crane) and crocodilians, (6) the latter taxa differ from parrots in a plesiomorphic elongation of the distal centriole, and (7) is a unique apomorphy of parrot sperm relative to other nonpasserines and reptiles. The short midpiece of N. hollandicus distinguishes this cacatuine from the two psittacines.

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Electron microscope study of spermiogenesis inCaiman crocodylusL.

Cited by 22 publications

References 10 publications

A novel transient structure with phylogenetic implications found in ratite spermatids

A novel transient structure with phylogenetic implications found in ratite spermatids

Reptilian spermatogenesis

Spermatozoal ultrastructure in three species of parrots (Aves, psittaciformes) and its phylogenetic implications

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