Variation in sperm morphology of a murine rodent from South-East Asia: the Greater Bandicoot Rat, Bandicota indica

Publication Type:Journal Article
Year of Publication:2011
Authors:Alibardi, L, Thitipramote, N, Suwanjarat, J, Leigh, C, Breed, WG
Journal:Acta Zoologica
Volume:92
Pagination:187-200
Date Published:2011
ISBN Number:1463-6395
Keywords:Bandicota indica
Abstract:

Alibardi L. 2011. Histology, ultrastructure, and pigmentation in the horny scales of growing crocodilians. —Acta Zoologica (Stockholm) 92: 187–200. The present morphological study describes the color of hatchling, juvenile, and adult crocodilian skin and the origin of its pigmentation. In situ hybridization and immunostaining indicate that crocodilian scales grow as an expansion of the proliferating epidermis of the hinge region that form thin lateral rings. In more central areas of growing scales, new epidermal layers contribute to increase the thickness of the stratum corneum. The dark pigmentation and color pattern derive from the different distribution of epidermal and dermal chromatophores. The more intensely pigmented stripes, irregular patches and dot-like spots, especially numerous in dorsal scales, derive from the incorporation of the eumelanosomes of epidermal melanocytes in differentiating beta cells of the epidermis. Dermal melanophores, mainly localized in the loose upper part of the dermis, also contribute to the formation of the dark or gray background of crocodilian scales. The eumelanosomes of dermal melanophores determine the darkening of the skin pattern in association with the epidermal melanocytes. Iridophores are infrequent, while xantophores are present in the species analyzed with a sparse distribution in the superficial dermis among melanophores. The presence of xantophores and of the few iridophores in areas where epidermal melanocytes are absent appear to determine the brown or the light yellow-orange background observed among the darker regions of crocodilian scales.Thitipramote, N., Suwanjarat, J., Leigh, C. and Breed, W.G. 2011. Variation in sperm morphology of a murine rodent from South-East Asia: the Greater Bandicoot Rat, Bandicota indica.—Acta Zoologica (Stockholm) 92: 201–205. In most mammals the male gamete, the spermatozoon, has a fairly consistent, species-specific shape although in a few species some variability is evident. The present study set out to determine the extent of sperm variability in a population of a South-East Asian murine rodent, Bandicota indica, that was sampled during both the breeding and non-breeding periods. We found that, regardless of the time of year when the animals were obtained, males had sperm present in the cauda epididymides but a high degree of variability was always evident including the presence of some grossly abnormal forms. The abundance of abnormal sperm tended to be greater during the non-breeding period. These animals also have relatively small testes, thus the occurrence of the variable sperm populations is consistent with the hypothesis that depressed levels of intermale sperm competition result in a relaxation of the genetic control of male germ cell maturation during spermiogenesis and thus the production of polymorphic sperm populations.

URL:http://dx.doi.org/10.1111/j.1463-6395.2010.00453.x
Thu, 2014-03-20 12:43 -- admin
https://secure.gravatar.com/avatar/5ade1b012674ce3dd941e2ea5dd15cc1.jpg?d=https%3A//mammals.indianbiodiversity.org/sites/all/modules/contrib/gravatar/avatar.png&s=100&r=G
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith