Chromosome Behaviour during Spermatogenesis of Anopheles stephensi Sensu Stricto

摘要: 1. The testes of Anopheles stephensi sensu stricto are two pale yellowish, ellipsoidal bodies. Their wall consists an outer, tough, pigmented envelope, and inner squamous epithelial layer. nuclei various types resting cells within the characterized by a peripheral, basophilic crescent. anterior part testicular cavity is divided into cysts which hold spermatogonia primary spermatocytes. Germ at later stages differentiation held free posterior cavity.2. spermatogonial metaphase configuration pairs V-shaped autosomes pair unequal, subtelocentric sex chromosomes. homologous chromosomes exhibit somatic pairing. centromeres appear as distinct, non-staining gaps. centromere slightly off-median in one autosomal pairs.3. early spermatocytes show long, slender, chromomeric threads peripheral latter subsequently resolves deeply staining thread-like structures representing heterochromatic regions lightly nucleolar body. chromosomal undergo process uniform condensation to produce thick pachytene bivalents. nucleolus disappears diplotene. associate together only along short lengths their long limbs proximal centromeres. Terminalization chiasmata takes place during diakinetic bivalent symmetrical. spindle formed welldefined nuclear space surrounded thin limiting membrane. Tiny dotlike centrioles present. At first anaphase univalents disjoin normally. chromosomes, on otherhand, obligatory postreduction. lag separation. In dyads chromatids widely divergent except near centromere. telophase oval shape concentration chromatin.4. A interkinesis stage second prophase typical X or cross-shaped figures. Subsequently they constitute tangled group centre nucleus prometaphase stage. plate produced although duration only. precession anaphase. spermatid fall classes basis relative dimensions heteropycnotic dots.