Histological analysis of the development and maturation of ovaries in Baeacris punctulatus (Thunberg) (Orthoptera, Acrididae, Melanoplinae).

Abstract

Baeacris punctulatus is a Melanoplinae species of economical importance in Argentina. During the life of an insect, ovaries undergo changes characterized by morphological and phisiological cell alterations. Histological studies of the development and maturation of gonads in South American Acrididae are rare. The objective of this study is to provide information on the morphogenesis of the ovary and oogenesis during the embrionic, postembrionic and the imago stage of development. Captive females Baeacris punctulatus were obtained. They were fixed in Bouin and preserved in n-butilic alcohol. Specimens were placed in “paraplast” and 6 µm-thick segments were stained with Hematoxylin-Eosin, Trichrome of Mallory and Hematoxylin of Verhoeff. Results show that in this species, ovaries differentiate in the embryonic stage X, observing in the ovarioles the germarium with oogonia in mitosis. The oogonial meiosis begins before the hatching of the nymphs. The primary oocytes go through three stages of development. The first stage takes place between the embryonic stage XI and nymphal stage II. It develops in the germarium and it includes from preleptonema to paquinema. The second period goes from nymphal stage II to five days of the adult stage and it occurs in the vitelarium that includes the substage of postpaquinema and stages of previtellogenesis of the diplonema. The third period occurs between the fifth and fifteen days of the imago and it includes stages of vitellogenesis up to the synthesis of external covers, vitelline cover and corium. The first ovulations occur between the fifteenth and twenty-fifth day. It is during this period that the female reaches sexual maturity. These results provide information on the reproductive biology of B. Punctulatus, which may contribute to better species management.