Oogenesis in Tenebrio molitor: Histological and autoradiographical observations on pupal and adult ovaries

Abstract

(i) Nurse cells and oocytes in the telotrophic ovary of Tenebrio molitor L. (Insecta, Coleoptera-Polyphaga) are differentiated in the larval stadium. (ii) During pupation DNA synthesis occurs in the nurse cells and is probably associated with polyploidy; some of them become multinucleate. The functional significance of these events is interpreted as preparation for subsequent massive RNA synthesis. (iii) The oviducts incorporate [3H]thymidine and undergo elongation due to mitoses. This ceases at eclosion. (iv) RNA synthesis in the pupal ovary is low, but increases in the nurse cells and follicle cells just prior to eclosion. (v) In the adult ovary, once the growth phase has been initiated, a primary oocyte takes about six days to reach maturity. (vi) The nurse cells, though apparently lacking nucleoli, synthesize much stable RNA which reaches each oocyte via a trophic cord. (vii) The follicle cells undergo continuous DNA synthesis: some nuclei contain over 64 times the haploid amount of DNA. Replication is probably asynchronous within a nucleus: this may account for the phenomenon of simultaneous DNA and RNA synthesis in the follicle cells, which also lack nucleoli. (viii) Oogenesis has been divided into nine developmental stages, three of which are vitellogenic. (ix) The oocyte chromosomes are capable of RNA synthesis both when despiralized during early previtellogenesis and after karyosome formation, which occurs at stage 6. (x) The protein content of the oocyte appears to have a dual origin: at least part of the ooplasmic proteins form in situ; while yolk proteins are derived from the haemolymph. The extra-ovarian protein reaches the oocyte via spaces which develop between the follicle cells. (xi) The nucleoplasm becomes more heavily labelled with proteins than the ooplasm. With [3H]leucine, methionine and phenylalanine but not with tryptophane or arginine, there is an increased incorporation into the karyosome. It is suggested that this karyosome-associated protein may function in gene masking. (xii) The significance of these findings is discussed with reference to the literature.

Antheraea peptide and its analog: Their influence on the maturation of the reproductive system, embryogenesis, and early larval development in Tenebrio molitor L. beetle

“…When the oocyte reaches the final size, the connection with the germarium completes its action. Follicular epithelial cells flatten, the spaces between them disappear, yolk deposition stops, and cells start to secrete chorion [ 9 ]. The effect of peptides on the growth and maturation process of the oocytes was assessed by measuring the size of terminal oocytes using the Olympus SZX12 stereomicroscope.…”

“…The female reproductive system of the T . molitor beetle consists of meroistic-telotrophic ovaries, which are functionally classified as asynchronous ovaries, which means oocytes do not grow simultaneously in all ovarioles [ 9 ]. Ovarian growth finishes in approximately 2 days, and maturation of oocytes occurs in the first few days (approximately 6 days) after the insects become imagos [ 10 ].…”

“…Therefore, to assess the effect of peptides on the formation and development of ovaries and to compare the results obtained, we focused on the assessment of parameters in females during the first ovarian cycle, i . e ., during the first 8 days after the transition to the imago stage [ 11 ].…”

“…However, considering the data about the strong antiproliferative properties of yamamarin and its effects on diapausing pupae of B. mori, we were interested in how this peptide affects insect reproduction processes from vitellogenesis through oocyte maturation, oviposition, and embryonic development up to larval hatching. The female reproductive system of the T. molitor beetle consists of meroistic-telotrophic ovaries, which are functionally classified as asynchronous ovaries, which means oocytes do not grow simultaneously in all ovarioles [9]. Ovarian growth finishes in approximately 2 days, and maturation of oocytes occurs in the first few days (approximately 6 days) after the insects become imagos [10].…”

Ovary Structure and Oogenesis of Trypophloeus klimeschi (Coleoptera: Curculionidae: Scolytinae)

“…There are two main types of data used in phylogenetic work of Coleoptera: morphological data of exoskeleton and internal organs [3][4][5][6], and molecular data [7,8]. The female reproductive system is a traditional characteristic of internal organs [9][10][11][12][13][14][15][16][17][18]. Especially with the improvement of micro technology in recent years, the research of female reproductive system is moving into more microscopic areas, like the structure and development of ovarioles [19][20][21].…”