Gonadal Biology of the Indian Native Killifish Aplocheilus lineatus
J.Michael Antony Prabhu Arachi *
Periyar Arts College, Cuddalore, 607 001, India.
M Sumaiya
C Kandaswami Naidu College for Women, Cuddalore, 1, India.
*Author to whom correspondence should be addressed.
Abstract
The present study was undertaken to provide in depth information on the gonadal cycle of Aplocheilus lineatus. Oocyte-size frequency distribution was also analyzed to pin-point the spawning season. One of the defining features of a species, therefore, is its reproductive strategy, as reflected in anatomical, behavioral, physiological and energetic adaptations. The males and females of killifish A. lineatus were randomly selected and standard length (SL) and total length (TL) were measured. Total length was measured from the tip of the lower jaw to the tip of the longest ray of the caudal fin. Oocyte diameters were measured in the randomly selected female gonads. A sub-sample of the ovarian tissue was removed and the oocytes were teased apart with needles in a petri dish filled with glycerol diluted to 30% with water. The ovary of A. lineatus was a paired saccular body with the investing wall of peritoneum, which led to the formation of ovisacs. Each ovary remained suspended in the body cavity by a mesentery, called mesovarium. The developmental stage of oocytes was determined by a microscopic examination of the ovary. The oogenesis of A. lineatus was categorized into thirteen developmental stages from oogonia to atretic oocyte. The sperm duct kept the continuation of its anterior part deep inside the testis and there it gave branching and sub-branching to form a system of tubules for collecting the sperm.
Keywords: Oocyte, mesovarium, caudal fin, spawning season