CHIASMA FREQUENCIES INLOLIUMPOPULATIONS

Expected Frequencies of Chromosome Associations in Tetraploids with Random Chiasma Formation.

N tetraploids the degree of multivalent formation at meiosis is often used as a 'wit erion of homology between the chromosome sets and gives information on the genetic control of chromosome association. Where the chiasma frequency of each association can be recorded in a number of cells, the observed association frequencies could be profitably compared with frequencies expected, assuming they a...

Differential Chiasma Frequencies in Self-pollinating and Cross-pollinating Species of the Genus Gilia

Ischemic chiasma syndrome.

Thirty patients with chiasma syndrome attributed to ischemic processes of various origins are described. The initial diagnosis was made after an investigation based on polytome pneumoencephalography and angiography. This diagnosis was confirmed later with the use of high-resolution computed tomography (CT) and refined angiographic techniques. The ischemic chiasma syndrome may be classified into...

Tumour of the optic chiasma.

Tumours arising in the small area at the base of the brain between the optic chiasma and cerebral peduncles are common and include meningiomas, suprasellar and pituitary neoplasms, aneurysm of the circle of Willis, and chiasmal arachnoiditis with cyst formation. Tumours arising in the optic chiasma and nerve sheaths, however, are very uncommon. In all these conditions, visual symptoms may obtru...

Glioma of Chiasma and Optic Nerve.

IN a case of orbital optic nerve glioma without intracranial extension, Davis (1940) removed the tumour through a skin incision at the lower orbital margin, cutting the optic nerve near the apex of the orbit and behind the globe and thus retaining the eye. Verhoeff (1922) found that, even when the tumour was partially removed by the orbital route leaving some intracranial portion, no orbital re...