| Reticulitermes aculabialis (Isoptera: Rhinotermitidae) belong to harmful insect, which damages mainly public buildings. At present, castes differentiation, oogenesis , the brain and sex hormone regulation of gonadal development, and the immediate early-gene c-fos neural activation underlying swarming behavior were investigated by histology, cytology and immunohistochemistry methods for probing into molecular regulation .The main results describe as follows:1.The caste of Reticulitermes aculabialis could differentiate into reproductives(SR),soldiers and workers.There are six kinds of reproductives in the nest,including alate,wingscale SR,shortwingbud SR(black form and light yellow form),microwingbud SR and wingbudless SR. Supplementary reproductives were generated from nymphs or workers of different instars. Soldier generated from worker above 4 instars.2. The oogenesis may be divided into seven stages: 1) The oocytes are located in the germarium and first meiotic division occurs at this stage. 2) Nucledi of nucleus disappears in the oocytes. The follicular cells begin to divide. 3) The oocyte, is surrounded by the follicular cells which form a single-layer in early period and then become to the columnar shape with two nucleus. 4 ) The yolk granules begin to deposit in the cytoplasm. 5 ) cytoplasm is gradually filled up with yolk granules. 6) Deposition of yolk ends and the follicular become into willow leaf shape. 7) Egg shell come into being.The conclusions that termites oogenesis are same as the other insects, basically are offered in this paper.The follicle cells not only invole in oocytes, but also participate in the regulation of oogenesis.3. Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH) play a crucial role in the oogenesis and spermatogenesis of vertebrates. Control of gonad development in insect also requires brain gonadotropins, but compared to vertebrates, the molecular structure of gonadotropins is far less clear. In vertebrates, FSH and LH regulate in gonad development,and the production of sex steroids(estrogens,androgens).However, it is unknown whether these two gonadotropins exist in the brain of insect, and involved in gonad development of insect. In the present study , the immunocytochemical localization of FSH and LH in the brain of termite (Reticulitermes aculabialis) were investigated with S ABC (strept avidin-biotin complex) method. The results indicated that FSH and LH existed in brains of differentdevelopmental stages. In the female, FSH immunopositive nerve cells and fibers were localized in the left, right, and middle part of procerebrum at flying stage and the right part of procerebrum at last instar nymph, LH immunopositive substance was localized in the left part of procerebrum at flying stage. In male, FSH and LH immunopositive substance was distributed in the right and left part of procerebrum at flying stage. No immunoreactivity for FSH and LH in this study was detected in brains of worker and soldier. On the other hand, we had known the oocyte of last instar nymphs were at growth stage which included follicular differentiation and proliferation, and the oocyte of flying female began to deposit in cytoplasm, and the spermatogenesis of flying male were transformation of spermatogonia to spermatozoa occurred.lt was shown that FSH and LH are involved in speeding up follicular growth and vitellogenesis in the female, and inducing spermatocyte maturation in the male.4. In mammal,immunocytochemical staining of Fos,the protein product of the immediate early-gene c-fos has been used to investigate neural activa within the neural network underlying sexual behavior,and it was clear that the forbrain played an important role in sexual behavior. In insect,it has been found that c-fos expressed in the brain. However,it is unknown whether c-fos expression in the brain of insect involved in sexual behavior. Swarming of termite was important sexual behavior. This study was undertaken first to examine the expression of the protooncogene c-fos in the brain of...
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