Now showing items 1-10 of 83
New occurrence of a macro B-chromosome in Astyanax scabripinnis paranae (Pisces, Characiformes, Characidae)
(Brazilian Journal of Genetics, 1994-01-01) [Artigo]
Cytogenetic studies performed on 17 specimens (11 females and six males) of Astyanax scabripinnis paranae from the Cascatinha stream showed that this population has 2n = 50 chromosomes (8M + 22SM + 10ST + 10A), two chromosome ...
Synaptonemal complex formation in spermatocytes of the autotriploid rainbow trout, Oncorhynchus mykiss (Pisces, Salmonidae)
(Hereditas, 1995-12-01) [Artigo]
Meiotic cells of triploid male rainbow trouts were analyzed by a surface-spreading SC technique in order to show the process of chromosome synapsis. At zygotene the formation of SCs involved, almost exclusively, two sets ...
A method for chromosome preparations from large fish specimens using in vitro short-term treatment with colchicine
(Experientia, 1993-09-15) [Artigo]
This paper describes a new technique for preparing mitotic fish chromosomes using short-term in vitro treatment with colchicine. The results show that a large number of good quality metaphases (many suitable for chromosome ...
Diversity of fish species in the River Paranapanema Jurumirim Reservoir transition region (São Paulo, Brazil)
(Italian Journal of Zoology, 1998-01-01) [Artigo]
The diversity of fish species in an transition zone between the River Paranapanema and the head mouth of the Jurumirim Reservoir was evaluated. Fish samples were collected from October 1995 to September 1996, by experimental ...
SPINDLE MEMBRANES DURING SPERMATOGENESIS IN DERMATOBIA-HOMINIS (DIPTERA, CUTEREBRIDAE)
(Journal of Submicroscopic Cytology and Pathology, 1995-10-01) [Artigo]
During the mitotic and meiotic division in Dermatobia hominis spermatogenesis, the nuclear envelope is fragmented and membranes appear around the spindle. The membranes surrounding the mitotic spindle are formed by two ...
A morphological and ultrastructural study of the paracloacal (Scent) glands of the marsupial Metachirus nudicaudatus Geoffroy, 1803
(Acta Anatomica, 1995-01-01) [Artigo]
Morphological and ultrastructural features of the paracloacal glands of Metachirus nudicaudatus are described. Two pairs of glands, one on the right and the other on the left of the anal canal, are formed, each consisting ...
Increased B chromosome frequency and absence of drive in the fish Prochilodus lineatus
(Heredity, 1997-11-01) [Artigo]
The neotropical freshwater fish species Prochilodus lineatus (Pisces, Prochilodontidae) shows 2n = 54 chromosomes plus supernumerary microchromosomes ranging in number from zero to seven among different animals. The ...
Centriole behaviour during meiosis of male germ cells of Dermatobia hominis (Diptera:Cuterebridae)
(Cytobios, 1996) [Artigo]
During the meiotic division of Dermatobia hominis spermatogenesis, the centrioles duplicate only in prophase I, giving rise to short cilia which are exposed on the cellular surface. In metaphase I they are internalized and ...
NUCLEOLAR CHROMOSOME VARIANTS IN STERNOPYGUS-MACRURUS (PISCES, STERNOPYGIDAE) FROM 3 BRAZILIAN RIVER BASINS
(Caryologia, 1993-01-01) [Artigo]
The karyotypes, location of nucleolus organizer regions (NOR) and constitutive heterochromatin pattern of Sternopygus macrurus (Pisces, Gymnotoidei) of natural populations from the Amazon River, Sao Francisco River and ...
Homology analysis in R-banded chromosomes from two Characidae (Pisces) species, Astyanax bimaculatus (2n = 50) and Astyanax schubarti (2n = 36)
(Cytogenetics and Cell Genetics, 1998-01-01) [Resumo]