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Ultrastructure and motility of spermatozoa in macropodid and potoroidid marsupials
D A Taggart1, C M Leigh, D Schultz
1Department of Anatomy and Histology, University of Adelaide, Australia.
Abstract:
In order to gain some understanding of the significance of the morphological features of spermatozoa within the Macropodoidea, the motility of spermatozoa from two macropodids (Petrogale xanthopus and Dendrolagus matschiei) and the motility, number and distribution of spermatozoa from three potoroidids (Aepyprymnus rufescens, Bettongia penicillata and Potorous tridactylus) were examined. Sperm were collected by electro-ejaculation or from the cauda epididymides. Epididymides from the potoroidids were divided into 12 regions. One epididymidis per animal was fixed for light and transmission electron microscopy and, on the contralateral side, the number of sperm, their distribution and motility were determined. In general, spermatozoa of all five species differed markedly from one another in head and flagella dimensions. Spermatozoa from B. penicillata and P. tridactylus were significantly longer and broader and had a smaller acrosome relative to head length, and there was a radial displacement of dense fibres. They also progressed more rapidly in standard culture media. Spermatozoa from at least three species were able to alter their motility pattern in vitro as media viscosity increased. Sperm movement in all species appeared to be restricted to one plane and showed no evidence of rotation, whereas lateral head displacement was often pronounced; there was no evidence of a sinusoidal mode of progressive motility. Testicular and epididymal sperm numbers in A. rufescens and P. tridactylus were relatively high (approximately 17.5-50 x 10(6)). In A. rufescens, approximately 69% of all epididymal sperm were located in the cauda epididymidis compared with approximately 40% in P. tridactylus. This study demonstrated that marked radial displacement of the dense fibres is probably closely associated with the ability to develop a sinusoidal mode of progressive movement, and that this feature of the sperm tail structure is not just linked with sperm size. Sperm size, however, is associated with sperm velocity.
Insights
Sperm morphology in kangaroos and wallabies varies significantly, with larger sperm size correlating to faster movement. Radial displacement of dense fibers is linked to sinusoidal sperm motility patterns.
Area of Science:
- Reproductive Biology
- Zoology
- Sperm Motility
Background:
- Sperm morphology is crucial for understanding reproductive success in marsupials.
- Macropodoidea spermatozoa exhibit diverse morphological features.
Purpose of the Study:
- To investigate the relationship between sperm morphology and motility in selected macropodids and potoroidids.
- To understand the functional significance of sperm structural variations.
Main Methods:
- Sperm were collected via electro-ejaculation or from cauda epididymides of five marsupial species.
- Sperm motility, number, and distribution were analyzed.
- Light and transmission electron microscopy were used to examine sperm structure.
Main Results:
- Significant species-specific differences in sperm head and flagella dimensions were observed.
- Spermatozoa from Bettongia penicillata and Potorous tridactylus were longer, broader, and moved faster.
- Radial displacement of dense fibers correlated with sinusoidal progressive movement, independent of sperm size.
Conclusions:
- Sperm size is associated with sperm velocity.
- Radial displacement of dense fibers is a key factor for developing specific motility patterns.
- Morphological variations in spermatozoa reflect functional adaptations in Macropodoidea.