Contribution of the secretory material of caecilian (amphibia: Gymnophiona) male Mullerian gland to motility of sperm: a study in Uraeotyphlus narayani.
Caecilians are a unique group of limbless burrowing amphibians with discontinuous distribution. Several caecilian species are viviparous, and all practice internal fertilization. In amniotic vertebrates the sperm undergo post-testicular physiological maturation when they are initiated into motility under the influence of an epididymal secretion. Further, during ejaculation mammalian sperm are suspended in a fluid secreted by the male accessory sex glands, viz., prostate gland and seminal vesicles. Caecilians lack comparable glands, but still practice internal fertilization. Uniquely, male caecilians retain the Mullerian ducts in the adults as a pair of functional glands. It has long been hypothesized, based on indirect evidence, that the Mullerian gland would be a male accessory sex gland, secreting a fluid in which sperm are suspended during ejaculation and which would also provide nutritional support to the ejaculated sperm. In the present study, the secretory material of the Mullerian gland of Uraeotyphlus narayani was mixed with sperm obtained from the testis, and the changes in motility were recorded. Uraeotyphlus narayani sperm possess a perforatorium of the acrosome proceeding deep into the endonuclear canal of the nucleus. The midpiece is characterized by closely applied centrioles, the anterior ends of the axoneme and axial fiber, and a mitochondrial sheath. The long tail has an undulating membrane on one side, supported by the axoneme and an axial fiber. The live sperm possess a mitochondrial vesicle, also known as the cytoplasmic droplet, anywhere along the head and the midpiece, as in anuran sperm, which is shed from sperm that have ceased motility. Uraeotyphlus narayani sperm are motile the moment they are released directly from the testis, indicating that the sperm do not require post-testicular physiological maturation. On being mixed with the secretory material of the Mullerian gland, the spermatozoa are enhanced in speed as well as duration of motility. Therefore, the caecilian male Mullerian gland is considered to be the male accessory sex gland.
George
Jancy M
JM
Department of Animal Science, Bharathidasan University, Tiruchirappalli-620024, India.
Smita
Mathew
M
Kadalmani
Balamuthu
B
Girija
Ramankutty
R
Oommen
Oommen V
OV
Akbarsha
Mohammad A
MA
D000663:Amphibians / Q000033:anatomy & histology / Q000502:physiology*; D000818:Animals; D002478:Cells, Cultured; D005088:Exocrine Glands / Q000502:physiology*; D008297:Male; D012098:Reproduction / Q000502:physiology; D013081:Sperm Motility / Q000502:physiology*; D013094:Spermatozoa / Q000166:cytology / Q000502:physiology*; D013737:Testis / Q000166:cytology / Q000502:physiology