Endocrine regulation of ovarian development, respiration, and fat body mitochondrial respiratory enzymes in adult female Blaberus discoidalis Serville

Abstract

These studies were designed to investigate effects of a corpora cardiaca (CC) extract upon oocyte maturation, respiration and synthesis of mitochondrial respiratory enzymes in females of the cockroach, Blaberus discoidalis Serville. Normal females commenced mating on day 4 at their peak rate, however virgin females were used for most studies to avoid surgical-induced problems with mating. Virgin and mated females appear similar in their reproductive development. Virgin females matured oocytes (although not fertile) and formed oothecae in 24 days, while mated females required 18 days for the same process. Juvenile hormone III (JH) was shown to be absolutely essential for oocyte maturation in this cockroach. The effect of JH was dose-dependent, reaching a maximum at a dose of 500 ng of JH per day. Injections of JH, plus homogenates from the CC of 1-day-old females, into decapitated females, stimulated the growth of oocytes above the levels of a JH + muscle-extract injected control group at 10 days of age. Two separate assays were used to measure stimulation of oocyte growth. Measurements of terminal oocyte length showed a 12% increase due to CC extract, while measurement of total ovarian protein showed a 44% increase in the same animals. The measurement of total ovarian protein was shown to be a more sensitive and accurate assay for ovarian development than was oocyte length. Injections of JH + male CC extract and JH + CC extracts from females of the same age as those being injected, caused an increase in total ovarian protein of 35% and 32% respectively above control levels.