The ultrastructure of the spermatozoon of the northern water snake, Nerodia sipedon (Colubridae, Serpentes), with phylogenetic considerations

1994 ◽  
Vol 72 (9) ◽  
pp. 1648-1652 ◽  
Author(s):  
B. G. M. Jamieson ◽  
L. Koehler
Keyword(s):  
Base Plate ◽  
Mature Spermatozoon ◽  
Boiga Irregularis ◽  
Nerodia Sipedon ◽  
Fibrous Sheath ◽  
Dense Bodies ◽  
Water Snake ◽  
Northern Water Snake ◽  
Distal Centriole ◽  
Electron Lucent

The ultrastructure of the spermatozoon of Nerodia sipedon conforms closely to that of other described snake sperm: it is filiform; the acrosome vesicle is in the form of a hollow, concentrically zoned cone that basally overlies a subacrosomal cone which invests the tapered anterior end of the nucleus; the putative perforatorium is a slender rod extending anteriorly from the subacrosomal cone; the midpiece contains dense bodies and mitochondria; the axonemal fibrous sheath extends anteriorly into the midpiece (squamate autapomorphy); 9 peripheral dense fibres surround the distal centriole and the axoneme in the midpiece, of which fibres adjacent to 3 and 8 are enlarged; and the endpiece lacks peripheral fibres and the fibrous sheath. The midpiece is very long (a synapomorphy of the Serpentes) and is surrounded by a multilaminar membrane (an autapomorphy). In the squamates, only snakes, including N. sipedon, retain microtubules external to the plasma membrane of the mature spermatozoon. Helically arranged zigzag mitochondria are shared (probably homoplasically) with iguanid sperm. A poorly developed "stopperlike" putative perforatorial base plate in N. sipedon, unknown in other snakes, is questionably homologous with that of gekkonids. An electron-lucent space caps the nuclear point, as in the snakes Boiga irregularis and Stegonotus cucullatus and in some other squamate orders.

The ultrastructure of the spermatozoa of the worm lizard Amphisbaena alba (Squamata, Amphisbaenidae) and the phylogenetic relationships of amphisbaenians

1999 ◽  
Vol 77 (8) ◽  
pp. 1254-1264 ◽  
Author(s):  
Ruscaia D Teixeira ◽  
Guarino R Colli ◽  
Sônia N Báo
Keyword(s):  
Transverse Section ◽  
Base Plate ◽  
Sister Group ◽  
Mature Spermatozoon ◽  
Fibrous Sheath ◽  
Dense Bodies ◽  
Intrafamilial Variability ◽  
Anatomical Characters ◽  
Phylogenetic Hypotheses ◽  
Constraint Tree

We describe the ultrastructure of epididymal spermatozoa of Amphisbaena alba and make comparisons with spermatozoa of other squamates. The mature spermatozoon of A. alba is filiform and characterized by the following features: the acrosome is depressed in transverse section; the perforatorial base plate is absent; the perforatorial tip is pointed; the perforatorium is single; the epinuclear lucent zone is well developed; the midpiece is moderately long; the mitochondria are columnar, forming regular circlets interrupted by dense bodies in transverse section; the dense bodies are solid, arranged in regular rings and linear series; the nuclear shoulders are rounded; the nucleus is elongate; the endonuclear canal is absent; fibers 3 and 8 are enlarged; multilaminar membranes are absent; and the fibrous sheath is in the midpiece. A phylogenetic analysis of squamates using spermatozoon-ultrastructure characters resulted in 2415 equally parsimonious, largely unresolved trees. The use of a constraint tree derived from gross anatomical characters suggested that the Amphisbaenia is the sister-group of the Autarchoglossa. We conclude that to improve the resolution of phylogenetic hypotheses derived from spermatozoon-ultrastructure characters, the number of characters ought to be increased, and more investigations are necessary to ascertain the degree of intrafamilial variability.

Ultrastructure of Spermatozoa of Elaphe schrenckii (Reptilia, Squamata)

2020 ◽  
Vol 27 (3) ◽  
pp. 149-155
Author(s):  
Shan-Shan Wang ◽  
Yu-Yan Lu ◽  
Chen-Hao Yao ◽  
Shuo Qi ◽  
Jian-Xin Cheng ◽  
...  
Keyword(s):  
Cross Section ◽  
Neck Region ◽  
Base Plate ◽  
Laminar Structure ◽  
Fibrous Sheath ◽  
Dense Bodies ◽  
Transmission Electron ◽  
Principal Piece ◽  
Distal Centriole ◽  
The Stability

Elaphe schrenckii (Serpentes, Colubridae), a kind of large nonvenomous snakes and great significance to maintain the stability of ecosystem in China. We provide detailed descriptions of the sperm microstructure and ultrastructure of E. schrenckii, experimented by light microscope and transmission electron microscope. The spermatozoon of E. schrenckii is filiform and consists of head and tail regions. The cross-section of acrosomal vesicle is always rounded and divided into medulla inside and cortex outside. The ultrastructure of acrosome complex observed the unilateral ridge, the single perforatorium, the perforatorium base plate, the epinuclear lucent zone, the subacrosomal space and the nuclear fossa at the end of nucleus connect the neck region. The neck region is short with the stratified laminar structure and observed the distal centriole and the proximal centriole are perpendicular and both consisted of nine triplets. Midpiece is long and observed the extracellular microtubules, the multilaminar membranec, the mitochondria with the dense bodies discontinuity distribting, the fibrous sheath, and the axoneme. The principal piece is after the annulus with no mitochondrias and the end piece with no mitochondrias neither the fibrous sheath. Our study contrasted the spermatozoa ultrastructure of 8 species belong to 5 families and 6 genera and added the sperm measurement compare, summarized that three Colubridae snakes are more similar than others momentarily but some specific characteristics in E. schrenckii and proved that the ultrastructure of sperm related to phylogeny in some ways.

Variation in offspring sex ratios in the northern water snake (Nerodia sipedon)

1998 ◽  
Vol 76 (12) ◽  
pp. 2200-2206 ◽  
Author(s):  
Patrick J Weatherhead ◽  
Gregory P Brown ◽  
Melanie R Prosser ◽  
Kelley J Kissner
Keyword(s):  
Sex Ratio ◽  
Sex Ratios ◽  
Birth Date ◽  
Nerodia Sipedon ◽  
Water Snake ◽  
In Captivity ◽  
Northern Water Snake ◽  
Northern Water Snakes ◽  
Gravid Females ◽  
Water Snakes

We used data from 88 litters of northern water snakes (Nerodia sipedon) to test predictions about how mothers would adaptively vary the sex ratios of their offspring. Larger mothers produced significantly more daughters (r2 = 0.04, P = 0.05), and mothers producing larger offspring produced significantly more daughters (r2 = 0.06, P = 0.02). Because neonate size did not vary with maternal size, these sex-ratio patterns were independent of each other. These patterns were more pronounced for wild females than for females maintained in captivity while gravid, but rearing conditions did not have a significant effect on sex ratio. Also, because sex ratios were similar between captive and free-living females despite captive females giving birth 16 days earlier, on average, and because sex ratios did not vary with birth date within the two groups of females, gestation appeared not to affect sex ratio. If females vary sex ratios adaptively, only the relationship between sex ratio and neonate size was consistent with our predictions. Limited evidence from other snake species also indicates variation in neonatal sex ratios that is nonrandom but not necessarily adaptive. A better understanding of these patterns will require information on the factors that affect the fitness of male and female neonates differently. An unexpected sex-ratio pattern that we found was that 14 of 19 stillborn young were male. We speculate that this pattern could be a result of male embryonic sensitivity to temperature. Thus, the need for gravid females to maintain a high body temperature so that their young are born with enough time to find hibernation sites may conflict with the need for embryos to develop at a safe temperature.

Sex ratios, mating behavior and sexual size dimorphism of the northern water snake, Nerodia sipedon

1995 ◽  
Vol 36 (5) ◽  
pp. 301-311 ◽  
Author(s):  
Patrick J. Weatherhead ◽  
Frances E. Barry ◽  
Gregory P. Brown ◽  
Mark R. L. Forbes
Keyword(s):  
Mating Behavior ◽  
Sexual Size Dimorphism ◽  
Sex Ratios ◽  
Nerodia Sipedon ◽  
Size Dimorphism ◽  
Water Snake ◽  
Northern Water Snake

Sex ratios, mating behavior and sexual size dimorphism of the northern water snake, Nerodia sipedon

1995 ◽  
Vol 36 (5) ◽  
pp. 301-311 ◽  
Author(s):  
P. J. Weatherhead ◽  
Frances E. Barry ◽  
Gregory P. Brown ◽  
M. R. L. Forbes
Keyword(s):  
Mating Behavior ◽  
Sexual Size Dimorphism ◽  
Sex Ratios ◽  
Nerodia Sipedon ◽  
Size Dimorphism ◽  
Water Snake ◽  
Northern Water Snake

Effects of Maternally-Transferred Methylmercury on Stress Physiology in Northern Water Snake (Nerodia sipedon) Neonates

2016 ◽  
Vol 96 (6) ◽  
pp. 725-731 ◽  
Author(s):  
J. Patrick W. Cusaac ◽  
Victoria Kremer ◽  
Raymond Wright ◽  
Cassandra Henry ◽  
Ryan R. Otter ◽  
...  
Keyword(s):  
Stress Physiology ◽  
Nerodia Sipedon ◽  
Water Snake ◽  
Northern Water Snake

Variation in offspring sex ratios in the northern water snake (Nerodia sipedon)

1998 ◽  
Vol 76 (12) ◽  
pp. 2200-2206 ◽  
Author(s):  
Patrick J. Weatherhead ◽  
Gregory P. Brown ◽  
Melanie R. Prosser ◽  
Kelley J. Kissner
Keyword(s):  
Sex Ratios ◽  
Nerodia Sipedon ◽  
Water Snake ◽  
Offspring Sex ◽  
Northern Water Snake
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