Postovulatory Follicle Degeneration and Atresia in Horse Mackerel <i>Trachurus trachurus</i> from the East Coast of Algeria

Abstract The present study focuses on the detailed description of postovulatory follicles (POFs) resorption and atresia in horse mackerel from Algerian waters. From February 2013 to February 2014, 155 female horse mackerel were randomly collected. Histological sections of ovaries were analyzed. Few POFs (7.28% of early POFs and 2.91% of old POFs of the total observed oocytes) were detected. Morphological changes of POF resorption were discussed in the current study. No particular shape was observed. Four types of atretic oocytes were determined: α = 34.38%, β = 5.28%, δ = 2.37% and γ = 0.94%, which was reported for the first time in horse mackerel. The incidence of α atresia was higher in the yolked (21.48%) than in the unyolked oocytes (12.89%). α atretic oocytes can be classified into two main types: non-bursting (capsulated, lipoidal and cystic atresia) and bursting (multiple bursts, single bursts, phagocytic bursts and liquified bursts). Further studies are required to better understand the reproductive strategies of fish in relation to postovulatory follicle resorption and atresia.