Biomaterial Database

The transformation of the Synaptonemal Complex into the 'elimination chromatin' in Bombyx mori oocytes. 1977

S W Rasmussen

In Bombyx mori oocytes the synaptonemal complexes are retained in modified from pachytene to metaphase I. At the end of pachytene the length and width of the lateral components of the complex increase, whereafter the complexes become compacted during later stages of the meiotic prophase. Ultimately, at metaphase I the modified synaptonemal complexes of individual bivalents fuse to form a more or less continuous sheet between the homologus chromosomes. This sheet corresponds to the structure historically known as the 'elimination chromatin'. It is concluded that in the absence of crossing over and chiasma formation in Bombyx mori females the retainment and subsequent modification of the synaptonemal complex has evolved as a substitute mechanism to ensure regular disjunction of the bivalents.

UI	MeSH Term	Description	Entries
D008540	Meiosis	A type of CELL NUCLEUS division, occurring during maturation of the GERM CELLS. Two successive cell nucleus divisions following a single chromosome duplication (S PHASE) result in daughter cells with half the number of CHROMOSOMES as the parent cells.	M Phase, Meiotic,Meiotic M Phase,M Phases, Meiotic,Meioses,Meiotic M Phases,Phase, Meiotic M,Phases, Meiotic M
D008854	Microscopy, Electron	Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.	Electron Microscopy
D009865	Oocytes	Female germ cells derived from OOGONIA and termed OOCYTES when they enter MEIOSIS. The primary oocytes begin meiosis but are arrested at the diplotene state until OVULATION at PUBERTY to give rise to haploid secondary oocytes or ova (OVUM).	Ovocytes,Oocyte,Ovocyte
D009866	Oogenesis	The process of germ cell development in the female from the primordial germ cells through OOGONIA to the mature haploid ova (OVUM).	Oogeneses
D009940	Organoids	An organization of cells into an organ-like structure. Organoids can be generated in culture, e.g., self-organized three-dimensional tissue structures derived from STEM CELLS (see MICROPHYSIOLOGICAL SYSTEMS). They are also found in certain NEOPLASMS.	Organoid
D010063	Ovum	A mature haploid female germ cell extruded from the OVARY at OVULATION.	Egg,Egg, Unfertilized,Ova,Eggs, Unfertilized,Unfertilized Egg,Unfertilized Eggs
D002843	Chromatin	The material of CHROMOSOMES. It is a complex of DNA; HISTONES; and nonhistone proteins (CHROMOSOMAL PROTEINS, NON-HISTONE) found within the nucleus of a cell.	Chromatins
D005260	Female		Females
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D012831	Bombyx	A genus of silkworm MOTHS in the family Bombycidae of the order LEPIDOPTERA. The family contains a single species, Bombyx mori from the Greek for silkworm + mulberry tree (on which it feeds). A native of Asia, it is sometimes reared in this country. It has long been raised for its SILK and after centuries of domestication it probably does not exist in nature. It is used extensively in experimental GENETICS. (From Borror et al., An Introduction to the Study of Insects, 4th ed, p519)	Bombyx mori,Silkmoths,Silkworms,Silkmoth,Silkworm,Bombyx morus,Bombyxs,mori, Bombyx