What's the difference between diastem and diaster?

Diastem

Definition:

Example Sentences:

(1) Analysis showed a reduction in the horizontal linear measurements, but not in the length of the mandibular diastem.
(2) The span and type of dental losses have influenced the frequency of the presence of such changes as: cheeks' retraction, intensifying of nasolabial sulci, lowering of vertical dimension of the bottom face segment, attrition of teeth, presence of diastems in the maxilla and mandible, enlargement of the resting mouth silt etc.
(3) The prominent palatal rugae of the diastemal region abet this process.

Definition:

(n.) A double star; -- applied to the nucleus of a cell, when, during cell division, the loops of the nuclear network separate into two groups, preparatory to the formation of two daughter nuclei. See Karyokinesis.

Example Sentences:

(1) We infer that elevated temperature induces unique changes in the microtubules of the pre-prophase sperm aster-diaster, resulting in cytoplasmic rotation and the spiral configuration of microtubules.
(2) Diaster medicine represents a new, multidisciplinary and comprehensive approach.
(3) In our study, these structures did not occur at culture temperatures below 16 degrees C. When the culture temperature was elevated, however, "spiral asters" routinely appeared during a susceptible period before mitotic prophase when the sperm aster-diaster normally exists.
(4) The author describes a training program in diaster-relief agencies.
(5) In one of the seminal works on visual agnosia, Adler (1944, 1950) presented the case of a 22-yr-old woman who sustained carbon monoxide cerebral toxicity in the Cocoanut Grove nightclub diaster of 1942.